Old Timing Chain


Front Timing Area


Timing Chain Tensioner Bolts - I used a breaker bar. They were pretty tight, enough that an impact driver couldn't loosen them.


Front Timing Chain Tensioner; very little tension on this little guy!


Rotating the engine in order to set it on a work bench.


Engine on work bench; wood underneath ensures the weight of the block is not applying pressure on the crankshaft.


Engine on work bench; wood underneath ensures the weight of the block is not applying pressure on the crankshaft.


Engine on work bench; wood underneath ensures the weight of the block is not applying pressure on the crankshaft.


Rear Cover Removal; oh the trouble begins.....



Pry the cover off here.


Gross.


Removal of the balance shaft chain tensioner.





With the bearing brace/caps not installed (a mistake on my end), there is still too much tension on this chain. Take one hand (not shown due to working the camera) and try to pull the chain off the crankshaft.....


.....then take a rubber mallet and give the crankshaft a few whacks while you are trying to pull the chain off the crankshaft gear. After a few whacks, I was able to break it loose. All of this can be avoided by waiting to remove the bearing brace/caps until AFTER this balance shaft chain is removed.



Pry HERE...


Not here (on this broken piece).

 

To remove this.....bearing thingy?, first use an allen key to hold it into place. Then grip it with channel locks, and loosen the bolt.


Note to all: this is a RIGHTY-LOOSEY bolt.




Bearing puller to remove the broken piece.


Balance shaft gear/bearing thing removed.


Notch in the shaft to keep it in time with the gear.


Another view.


Balance Shaft Gear removed


Another notch in the gear; this means the gear can only be installed onto the shaft one way (a good thing)


Balance Shaft & Gear - The only reason I had to do this was because I was clumsy and broke the delicate piece of flange, and I needed to break down the shaft in order to install the (new) flange piece onto the shaft. If you're not a moron like me, then you won't have to do any of this. Just be careful, because these parts are extremely delicate. The new shaft is not in yet, therefore I do not have pictures.


Cylinder Scoring :-( - and yet I thought I would be able to re-use these.


More Scoring.


.....and more.


Scoring on the pistons; on the thrust side.


Dirty pistons;


Dial Bore Gauge on the cylinders; If not for the scoring, these likely would have been reusable.




Everything removed.


Not too terrible....??.....not great, but not terrible.



.....yeah that's bad. Actual pitting on the main bearing. LAST picture for Part #2

Misc.


Here is a great video online (relatively short) that shows you the basics of using a dial-bore gauge.

End of Part 2

 

Part #3 - Reassembly

**Final Budget will be included at the very end, with ways to save a whole lot of money**

Balance Shaft Bearings Update - I was unable to remove these with a universal camshaft bearing removal/installation tool. My thought was I would be able to insert the tool into the balance shaft bearing, tighten the rubber piece on the universal tool to apply pressure, then remove them by attaching a slide hammer to the camshaft tool. Unfortunately this method did not work, and I was unable to get creative enough to find other (safe) ways to remove the bearings. I ended up ordering the Balance Shaft Bearing specialty tool from Ebay for nearly $700, however the seller (despite advertising a "complete set") did not send me several crucial parts of the tool to complete the task. I am now trying to work with them to send me the remainder of the tools, however bottom line, I did not remove/replace the balance shaft bearings. Upon inspection of the old bearings that were still in the engine block, they (surprisingly) were still in rather good shape, and the balance shafts both rotated freely when installed. While this may have been a hasty decision (not wanting to wait for the correct tool), I decided to just re-use the bearings that were still in the engine block.

Cylinder Sleeves Update - I also ordered the specialty tools required to remove/replace the cylinder sleeves. I removed/replaced the sleeves myself, but while a great learning experience, this was 100% not necessary. The only cylinder sleeves available for this engine are Semi-Finished, meaning they have to be bored/honed (Melling CSL356F). Unless you have the ability and means necessary to perform the boring/honing yourself, you will have to take your engine block to a shop for honing. The shop asked for my pistons & main bearing brace/caps in order to perform the honing process. Bottom Line, do not waste money on the specialty tools required to remove/replace the cylinder sleeves. Simply order the sleeves, take the block and the sleeves to a reputable shop and they should be able do the rest. If anyone is in the southern area (Mississippi), I can provide you with the shop I used in a PM if interested.

The shop also cleaned my engine block, bearing brace, main bearing caps, and resurfaced the engine deck as well, all free of charge (a nice bonus).

Crankshaft Issues - When I went to inspect the (old) crankshaft in this engine, one of the journals was nearly 2mm out of round. I called several shops in the Mississippi, Alabama, and Florida area to see if anyone would be able to weld/regrind the journal; not a single shop was willing to perform this work on this engine. Many believed that the casting on this particular crankshaft is less than ideal and welding it would sacrifice the integrity of the metal and most likely cause it to fail in a short timeframe. Whether this is true or not, I do not know (not a metallurgist) but bottom line, if your crankshaft is out of tolerance, good luck finding a shop to work on it.

Fortunately, there are some aftermarket options available: a company called "Heavy Duty Parts Company" has a replacement available. I called them on the phone to ask about their castings/etc. and they perform everything in house. Their customer service seemed to be top notch as well, so I have little doubt they are a fairly solid company. The problem is their crankshaft for this particular engine is nearly $1000, which is why I did not order from them. Fortunately, I got lucky and found a brand new GM Genuine crankshaft online for only about $700 on Ebay. There are various other aftermarket options available on Amazon/Ebay but I was a little skeptical about choosing an aftermarket brand for something as important as a crankshaft.

Now for the Good Stuff - Finally, with new cylinder sleeves, a new crankshaft, a rebuilt cylinder head, and a nice clean engine block, I could finally start reassembling everything. I'll let the pictures do most of the talking.


Fresh Engine Block


Cylinder Honing


Cylinder Honing (2)


Balance Shafts - I was able to repair the damaged balance shaft (from Part #2) by ordering a $50 balance shaft for a Chevy 2.9L, removing the broken piece, and replacing it on this balance shaft (you can see the new shiny part compared with how dirty the rest of the shaft is). These bolts are LEFTY-TIGHTY, RIGHTY-LOOSEY. I used a little bit of blue thread-locker when reinstalling the bolt.


New Crankshaft and Balance Shafts - I did not replace the balance shaft bearings.



New Main Bearings


Piston & Connecting Rod - The 2x small snap rings that hold the piston pin in place was a PITA to assemble without a specialty tool, but I got there eventually. I did not capture it on camera, however on the connecting rods, there is a small oil control hole that should be facing towards the exhaust side of the engine. MAKE SURE you have this oriented properly. Reference the Schwartz service manual for the 3.7L engine for more information.


New piston; ensure the valve grooves are on the Exhaust Side of the engine. I re-emphasize, the small oil control hole on the connecting rods should be facing the exhaust side of the engine as well.


Did I mention the small oil control hole should be facing the exhaust side of the engine?


Installing the piston rings using a ring installer tool. If you order the kit from Mizumo Auto, they clearly label the upper/middle/lower rings which makes it a breeze to install these. Be sure to reference the Schwartz Service Manual for the 3.7L engine as well. The bottom oil control ring (which is two small rings, and a "separator" in the middle) did become slightly problematic, as they are all incredibly flimsy and did not want to seat properly and could get tangled up with one another if not careful. Be extremely delicate with the bottom rings, and do not "force" them into place. Once you have "all" of the piston rings installed, place the rings all 90 degrees off from one another. The ring material with the Mizumo Auto kit is Steel Nitrated.


Ensure the connecting rod bearing lines up with the small oil control hole.


The connecting rods are the Engine Tech brand.




The bolts that came with the Engine Tech connecting rods were VERY tight and required a lot of force to loosen. Since these are torque to yield bolts, I did not trust re-using them, so I ordered 10x GM Genuine connecting rod bolts.


Installing new bolts. The connecting rod bolts are first tightened to to 18 ft-lb, then an additional 110 degrees. Do not reuse old connecting rod bolts.


Bottom end completed. The Main Bearing Brace Bolts are tightened to 18 ft-lbs followed by an additional 180 degrees. Reference the Schwartz Service Manual for the correct order in which to tighten these (shown in the next picture).



Piston Direction - Valve Grooves face exhaust side.

One thing I did not take pictures of was installing the pistons down in the cylinders using a piston ring compressor tool. I purchased a cheap tool off of Amazon for this job; there are a lot of good videos out there that explain how to properly do this, but I am kicking myself for not taking pictures of that process. All in all though, it really wasn't that hard but just be patient; use lots of motor oil (or assembly lube), and do not force the piston down the cylinder. If you catch any resistance, then one of the rings most likely came out of place (happened to me on one of the oil control rings); take the piston out, reseat the rings, and start over again.

Another section that I did not take pictures of (for re-installation) was installing the balance shaft chain, tensioner, and setting the appropriate timing marks. Once you have the bottom end installed (connecting rods, main bearings, and caps, etc.), this section was honestly not hard at all. Reference the Schwartz Service Manual for the proper timing marks on the balance shafts, crankshaft, and the balance shaft chains. Installing the tensioner is not difficult either. Again, apologies for not having pictures of this section.

There is more to Part #3 coming up shortly, but right now I am taking a lunch break. I'll have the remainder of this entire process uploaded hopefully by the end of today (tomorrow at the absolute latest). I'll have Part #3 completed, followed by Part #4 (Engine Testing Results), and Part #5 (Final Budget & Lessons Learned on the entire process).

Questions/Comments/Concerns/Criticism - I'm all ears!

 

Part 3 (Continued)


Balance Shaft Chain/Tensioner diagram.


Cylinder Head Added to top of engine (not shown in photos is adding the head gasket).


Tighten the cylinder head bolts using an angular gauge. They should be tightened to 22 ft-lbs followed by 155 degrees. These suckers get TIGHT!

Cylinder Head Tightening Diagram


Ensure you have the angular gauge zero'd out every time you tighten a cylinder head bolt


I knew I was on the right track when (after tightening all the cylinder head bolts), I ran a compression leakdown test in every cylinder and saw this! This was actually the "worst" cylinder, which showed barely about 10% leakage, and this is with the piston rings not even fully broken in yet! Much better than the 60% (40% leakage) I was getting in the previous engine!





Camshafts & Timing Chain installed. When installing the camshaft bearing cap bolts, tighten them to 106 in-lbs or about 9 ft-lbs. I rounded up to 10 ft-lbs and (so far) there have been no issues. Make sure you install the caps in the same order & direction that they were in before you removed them (taking pictures really helps).


Another view of the camshafts. For the Intake Camshaft Sprocket Bolt, tighten first to 15 ft-lbs, followed by an additional 100 degrees. For the Exhaust Camshaft Actuator Bolt, tighten to 18 ft-lbs, followed by 135 degrees. I re-used both bolts (could not find new bolts online), and applied some blue thread-locker to both bolts. So far, after about ~1000 miles of driving, they have held up just fine.


Timing Chain


Crankshaft Sprocket & Timing Chain - I reused the same sprocket but ordered a new chain, guides, and tensioner. Make sure one of the gold timing chain marks is lined up with the small "dot" on the crankshaft sprocket (hard to see in this photo, but the dot is located roughly in the 4:30 position, right above the gold chain link).


Ensure one of the gold timing chain marks touches the small "-" or "dash" symbol on the exhaust camshaft sprocket/actuator.


Ensure one of the gold timing chain links is positioned over the small "dot" (located roughly in the 12:30 position in this picture) on the Intake Camshaft Sprocket. Once you have all three lined up (crankshaft, exhaust, and intake sprockets), congratulations, your engine is mechanically in time. While it can be tricky, this can be accomplished without any specialty tools (during a rebuild, that is).


There are no cork/rubber/composite gaskets for the front timing cover/rear timing cover/ or the oil pan; sealing is accomplished using RTV gasket maker. Here is the (new) front timing cover and oil pump getting ready to be installed. The biggest things that can go wrong here is 1) not over-applying the gasket maker (you don't want large chunks getting in the engine one you mesh the two surfaces together) and 2) Not Being Patient - Follow the directions to a "t" on the RTV gasket maker; don't rush this step, since this literally is the only thing sealing your engine together. Additionally, if reusing any of the timing covers, ensure that all surfaces are clean and that all previous gasket sealant is removed prior to applying the new RTV sealant.


Cleaning the oil pan (take #1) - if your oil pan looks like this, be prepared to use about 2-3 cans of Parts Cleaner. I tried a generic (Super Tech) can first with a brass wire brush which sort of worked. I eventually stepped up my game and tried some Gumout Regane Parts Cleaner, which worked a lot better. After a considerable amount of time, I managed to get the oil pan to look like........


......this!!! Still not perfect, but much better than it was before. I plan to use Valvoline Restore & Protect oil to (hopefully) clean up the last little bit of carbon deposits inside the oil pan.


Another view of the oil pan, along with some RTV sealant. DO NOT forget to clean and install the OIL PICKUP TUBE (not shown in pictures) prior to installing the oil pan.........ask me how I know.....(actually don't....)


Front timing cover & water pump installed.


Oil Pan Installed - again, do not forget to install the oil pickup tube before this step (obviously).


New oil pressure sensor

 

Part 3 (Final)


Water Pump - notice one of the bolts is slightly larger than the others. This is because one of my (old) bolts broke; upon removal (with a bolt extractor tool), this broke too. I was able to drill out both of them, and re-tap the hole to a slightly larger thread. So far, it has held up just fine. Just be mindful that the water pump bolts are incredibly flimsy, and take care not to break them upon removal/reinstallation.


Front oil seal installed


Here is how I installed it, using an oversized socket.


Valve cover installed - cleaning it was done in the same fashion as the oil pan (Gumout Regane parts cleaner, and a brass wire brush).


Another angle.


Final Angle - great success, the engine is completely rebuilt!


My DIY attempt at drilling out the intake camshaft sensor port; this should only "need" to be done if your H3 is a 2006 or 2007, and you're using an engine from a 2008+. If this is the case, I would absolutely not perform this task without having an 06-07 head on hand (something that you can use as a template). I could not find a machine shop in my local area that would perform this task, so I did it myself. I used a Dremel Tool, a cordless drill, a lot of drill bits (to work my way up little by little), then took a metal file and smoothed everything out. The final hole I used was a 3/4" drill bit which is slightly too large but it did end up working just fine for me if you put some RTV sealant on the sensor body. 23/32" would be the exact fit for the larger hole. The clearance between the sensor and the intake camshaft sprocket is only 0.045" which you can check with a feeler gauge, so keep filing/trimming the surface down until you achieve this gap. As far as tapping the smaller hole, I simply used a universal tap and die kit that I've had for years. Despite being aluminum, it was a little bit harder to tap than I would have initially thought. I cannot stress the importance of having patience when performing this job; you want to get as close to the factory setup as you can; even having the sensor off center the smallest amount can play games with your engine's ECU timing and potentially throw a CEL code. H3 Humper has a great video on this job (link will be provided below).



If you have a manual transmission, make sure you have this bearing installed in the crankshaft, for your transmission intake shaft. Additionally, without it, it will also be impossible to center the clutch. I used blind bearing puller from Harbor Freight ($70, even cheaper online) to pull the bearing from my old crankshaft, then used a universal clutch alignment tool from Auto Zone to center the clutch after reinstalling the flywheel (not pictured) and both tools worked fine for this application. Compare this photo to earlier photos of the crankshaft (from the donor engine), which had an automatic transmission; they are different, as the automatics have some type of metal insert in the center, which I imagine is a (censored) to pull out. Don't let a small detail like this delay your project, especially if you've already gotten the engine assembled.

In no particular order, some things not shown in the pictures are:

1) Flywheel Installation - I reused the same bolts, applied some blue thread-locker to each bolt, and tightened them to the Schwartz Service Manual Spec (30 ft-lb, then an additional 45 degrees).
2) Clutch Installation & Centering (Manual Transmission Only) - I centered the clutch using an Auto Zone Universal Clutch Alignment Tool. I then applied some blue threadlocker to the pressure plate bolts and tightened them to 15 ft-lbs then an additional 45 degrees.
3) Oil Pickup Tube Installation
4) Old Engine Removal & New Engine Installation - This would be a whole separate thread in itself, but I was able to remove the old engine & install the newly rebuilt engine without removing the (manual) transmission. That said, it was a challenge, and the front of the engine had to be cocked up at an (almost) 45 degree angle slant to remove; there is not enough clearance in the engine bay to simply pull the engine forward (out of the transmission) and lift it straight up. There is a great video on Youtube (although it is an hour long) that explains every step of the way. One thing that does differ from the video, is I did not do anything to the front differential (didn't raise, lower, etc., just simply left it where it is). Once again, I emphasize patience, and taking thorough pictures, and also labeling the nuts/bolts/etc. along the way. Once you have the old engine out, you should have a decent amount of 10mm bolts laying around of slightly different lengths, and it is incredibly easy to get them mixed up if you don't separate them properly.

**I may add more to this list over time if I can think of anything else**

Links to Videos

 

Part 4 - The Results

The First 700 Miles

After four months of hours of work, dealing with the 90-95F heat, and the tons of bugs critters and mosquitos here in the south, I managed to get the vehicle back in one piece, and up and running.

Some initial quirks I had to work through:

1) Starter Problems - I replaced the starter (old one was dying and was badly corroded) with a Duralast Gold starter from Auto Zone. After the 5th start, I started getting the "click-click-click-click" sound similar to a dead battery. I first thought the starter went out on me, however it ended up being a faulty starter cable leading from the battery to the starter (for reference, I do not have the stock battery terminals). Apparently the car sitting for about a month (with the engine out) in the southern heat and humidity caused a little bit of corrosion on the starter end cable, which is what was causing the problem. It was small enough that I thought nothing of it, but apparently it was enough that it was causing the issue. I simply ran a separate battery cable directly from the battery to the positive end on the starter, and now she starts stronger than ever every single time.

2) Serpentine Belt Squealing - I replaced the old serpentine belt with a Duralast one from Autozone, which I am confident in saying is probably one of the worst belts out there. Horrible, horrible squealing at anything above 1500-2000 RPM, and no amount of baby powder, water, etc. could get it to go away permanently. I then purchased a Gates belt from O'Reilly's, which was smooth as a button regardless of engine RPM. Avoid Duralast Belts at all costs.

3) Variable Valve Timing Problems (P0017 CEL code) LONG TLR BELOW - Oh boy, this could also be a whole another thread in itself, but here we go anyways. After about 150 miles on the new engine of what (seemed) like trouble free driving, one day the car just shut down while idling in my carport. I thoroughly checked all my connections, revisited all of my work, and tried starting the vehicle again. This time, I was met with a very rough and erratic idling and the engine felt like it was going to eat itself. I immediately shut the engine down, plugged in my Scan Tool, and noticed the car had a Pending P0017 CEL code. Now I was really worried that something internally had malfunctioned with the engine.

During the rebuild, I had installed a brand new (non AC-Delco) aftermarket VVT Solenoid, which I immediately suspected was the problem, so I pulled it out, and re-installed the old AC Delco brand sensor. I let the car cool down for about 2 hours, then went to start the vehicle back up. Surprisingly, the problem went away and I thought the issue was simply the new solenoid acting up, so I cleared the CEL codes with the Scan Tool and took the vehicle for a drive just to make sure all was well. I drove the vehicle about 10 miles, stopped for gas, and then the problem reared it's ugly head again. On startup, I was greeted with another rough/terrible sounding idle, so I shut it down, pulled out the Scan Tool, and had another Pending P0017 Code. After letting the car cool down for some time, I was able to start the vehicle up, drive about 10 miles home on the highway with no issues, however when coming to stop, the problem would reappear, and I would have to continually restart the engine until the "problem went away" enough that I could drive it home.

So now I have tried 2x VVT Solenoids, and had the same problem with both. I began thinking about the crankshaft sensor, and wondered if a relearn would help, so I took the vehicle to the Stealership to perform a Crankshaft Relearn Procedure; the idle appeared to smooth out a considerable amount, but unfortunately the problem did not go away, and I would still get P0017 codes and stalls at idle.

I wondered about the type of oil that I was using, as I was running Driven 5W-30 Conventional Break In Oil which is a low detergent, high ZDDP formula, which is non API rated. Up to this point, I had already performed about 8-10 "dyno-runs" (to help seat the rings) with the break in oil, and had driven the car about 200 miles, so I figured it would be a good time to drain this oil, and replace it with my intended oil of choice (Valvoline Restore and Protect 5W-30) to see if that would make any difference.

So I drained the Break In Oil, added the Valvoline R&P 5W-30, and took her for a drive. I was able to drive about 10 miles on the highway at a constant 2200-2300 RPM in 5th gear, with no issues, and then low and behold, when coming to a stop, the car would stall out, and I would get a pending P0017 code. So at this point, I was pretty confident that the problem was only occurring as I was slowing down and coming to a stop.

This is where things take a turn for the better, because over time, with continued driving with the Valvoline Restore and Protect, things eventually got better. After 3-4x more heat up/cool down cycles, I stopped getting the P0017 code completely, but the car would still stall out when coming to a stop after about 10 miles of driving. Then little by little, I found that I could go 20 miles, before the problem would arise, then 30, 40, and so forth and so forth. Now, nearly 700 miles later on the new engine (about 500 of which is on the Valvoline oil), I am at the point to where the problem has essentially gone away completely, and I am able to comfortably drive roughly an hour with no stalls whatsoever. I have not yet tested this on a long trip yet (>100 miles), but for my daily everyday driving, the problem has gone away and the idle is incredibly, incredibly smooth.

So what happened then? Well I realized that one of the biggest things I did not replace brand new was the Exhaust Camshaft Phaser/Actuator, and instead installed a used one into the new engine (remember, this was a 2008 donor engine, that was going into a 2007 vehicle, so I needed a separate 2007 Exhaust Camshaft Actuator); during the rebuild I cleaned the actuator of carbon the best I could, however I did not bench test it with compressed air (didn't even realize this was possible until after the fact when I began researching this problem). When you drive this engine in a mid-range RPM (2200-2300 for example, on the highway), this is the range where the I-5's VVT retards the exhaust timing. Then, upon shifting into neutral, and the engine spools down to an idle RPM, the Cam Phaser is supposed to advance the exhaust timing back to it's "default" 0-degree natural resting position (the position the phaser is in with zero oil pressure).

What I believe was happening, was the Cam Phaser was Sticking/Not moving properly when going from it's retarded position (mid-range RPM on the highway) back to it's fully advanced position (idle RPM), which was causing issues with the PCM's timing, and what was ultimately causing the engine to stall. Essentially, VVT was being activated when the engine is at idle, which was causing the rough idle/horrendous sounds that I was experiencing. Whether there was some internal carbon build up, or some sludge within the mechanism, I do not know, but one way or another, after continued driving with the Valvoline Restore & Protect (an oil known for it's cleaning ability) the problem has all but gone away.

I do not chalk this entire ordeal up to the Driven Break In Oil in any way shape or form, nor do I know if the driven oil would have eventually worked out problem as well, but I figured there would be a better chance of "cleaning" the mechanism with the R&P oil, rather than the conventional Driven oil.

TL DR - Car was getting a P0017 code and horrendous rough idle from time to time. I performed a crankshaft relearn, which smoothed out the idle a little bit but ultimately did not fix the problem. I drained the break in oil and switched to Valvoline Restore & Protect, and little by little the problem went away. While no "definite" cause, I believe the exhaust cam phaser/actuator was sticking when going from highway speeds to idle RPM. It appears that the Valvoline oil has helped clean the Exhaust Camshaft Phaser, and now after about 500 miles on the oil, the problem has gone away.

Vehicle Performance - Power and MPG Test

In the very first post on this thread, I mentioned how my H3 was beginning to feel anemic and the MPG was beginning to suffer with the old engine. After diagnosing the problem, all 10 of my intake valves were leaking, and the engine was only producing about 60% compression (40% leakdown) on every cylinder.

With the rebuilt engine, with the Conventional Driven Break In Oil I was a little worried because at first I did not notice much of a difference in power. I remembered almost feeling "disappointed" that I spent so much time on this project to have very little (if any) gain. Low end power felt slightly bit better than the old engine, but I still remember feeling like I had to floor the accelerator for it to hold 60-65 mph (and this is with the A/C off by the way). The Driven Oil is Conventional and also contains higher levels of ZDDP, and also has no friction modifiers (all of which contribute to higher levels of internal friction), but I still was a little worried about how much of an effect this would truly have on the engine as a whole.

Fuel Economy (again with the driven oil) also wasn't tremendous, and on the very first test, I averaged about 17.3 miles per gallon with the A/C off the entire time (had not recharged it yet at this point).

However, once I had worked out the dreaded VVT issues and P0017 code, switched to the Valvoline R&P Synthetic Oil, performed a crankshaft sensor relearn, fully broke in the engine, and worked out all the little quirks, now I can tell the difference between the old engine and the new engine. Lower end torque is much, much higher than it was before, as I barely have to touch the gas to get the vehicle moving where I need to. Interstate driving is a breeze as well; while still not a rocket by any means, I can hold a very comfortable 65 mph, whether flat, going up an incline, etc. 70-75 mph is also not out of the question either if I need to pass someone without downshifting into 5th gear, and the vehicle overall doesn't feel quite as strained as it used to.

Fuel Economy has also improved as well, and I can comfortably average 17-17.5 mpg on the interstate with the air conditioning ON the entire time (compared to 17.3 with the Driven oil with the A/C off the entire time). Before, I was barely averaging 15-16 mpg at a measly 60-65 mpg.

(Continued on next page)

 

Part 4 (Continued) - Nerding out on Fuel Economy, Compression Ratio, and Thermal Efficiency

In the previous post, I mentioned how I was getting 15-16 mpg at 65 mph with the old engine, and now I am getting roughly 17-17.5 mpg at 65 mph with the new engine.

But you might be thinking "wait, you were averaging 60% compression on each cylinder before, and with the new engine, you're averaging 90%+ Shouldn't the MPG be roughly 30% higher, such as in the 19.5-20.8 mpg range?.........

(drum roll)....






Location of Compression Leakage

There are four locations where compression can be lost:

1. Intake Valves
2. Exhaust Valves
3. Piston Rings
4. Head Gasket

In the case of my old engine, almost all of the leakage was coming from the intake valves, as there was a considerable amount of air escaping through the throttle body during the leak-down test. Since the leakage was occurring at the intake valves, the fuel/air mixture is not simply lost into oblivion, but instead is being fed right back into the throttle body, and will (eventually) re-enter the cylinders, to be burned off. So the assumption is, there is no air/fuel mixture lost with intake valve leakage.

I did have a small amount of leakage from the piston rings as well, but in a similar fashion, the air/fuel mixture will leak past the rings, into the crankcase, and then eventually work there way back into the intake manifold via the PCV hose.

If the engine were losing compression due to exhaust valve leakage, or head gasket leakage, then the assumption of not losing any air/fuel mixture would not be the case, as the air/fuel mixture would be leaked into the exhaust, or worst case, your engine coolant. If this were the case, then you could expect a significant loss in fuel economy, since all of that air/fuel mixture is lost into oblivion.

So in my case (intake valve leakage), I wasn't losing any air/fuel mixture really anywhere, since it would eventually return to the intake manifold. So why was I getting lower MPGs with the old engine? It's because, with the intake valve leakage, and the overall lower compression numbers, the engine is effectively operating at a lower compression ratio, thus reducing the thermal efficiency of the engine.

How much of a reduction exactly? Well, in one of my other beloved vehicles, a 1993 Jeep ZJ with the 4.0L I6, the compression ratio is 8.8:1, and it produces right around 145-150 psi per cylinder (leak-down test reveals 5x cylinders are right around 10%, only one was at 15%). Since the old engine in the H3 (going back to the beginning of this thread) was reading around 135-150 psi, which is very to the Jeep engine numbers, the old H3 engine was effectively operating at a compression ratio of roughly 8.8 to 1. I realize this is a very, very simplistic estimation, and that the two engines differ in more ways than one, but for the purposes of what I am getting at, we will roll with it.

Now, with the new engine, that produces very little leakage, the engine is getting the most out of it's air/fuel mixture, and is operating at it's rated compression ratio of 10.3. I wonder what impact that will have on the thermal efficiency of the engine....

Compression Ratio & Thermal Efficiency

Referencing the chart below, we can see that an increase in compression ratio from 8:8 to 10.3 (again, going from the old engine's effective compression ratio to the new engine), there is an increase from roughly 57% to about 61%, or an increase in about ~4% thermal efficiency.



However this is the mathematical model for the Ideal Otto Cycle which does not take into account other factors such as ignition timing. What about testing the effects on real engines? One study experimented studied the effects of higher compression ratios in a 12.5L single cylinder ammonia-gasoline dual fuel marine engine, and reported a thermal efficiency increase of 5.8% when going from 13 CR to 14 CR. Another study estimated roughly a 6.6% increase when going from 8.0 to 10.0 CR.

With that, lets take a look at our mpg results from before and after the engine change.

Old Engine = 16.0 mpg (usually what I would "average" with the old engine. Sometimes I would get 15-16, and some times I would get lucky and get 16-17). 16 is a nice middle ground
New Engine = 17.25 mpg (the average of what I've been getting with the new engine)

% increase = ~7.8%.

Why is this more than the 4-5% from the charts/studies? Well for one, these are not "exact" numbers. With the old engine, sometimes I would get 15.5 mpg, sometimes I would get 16, somtimes 17.3, etc. They were all over the place. 16.0 mpg seemed to be a good estimate of the average of all of them. I also do not have as many "mpg tests" with the new engine to see if the 17+ mpg is a fluke, or if it is consistent.

Bottom Line, what does all of this mean? An increase in 30-40% compression does not necessarily mean an increase in 30-40% fuel economy.

 

Part 5 - Final Cost & Lessons Learned

Final Tally: $6800

Yikes! That is nearly double what I budgeted and then some, however this included absolutely everything. Everything, from the engine stand, the tools, parts, shop labor, etc. However, because I purchased a donor engine to rebuild, I now have (the old) engine sitting my carport which I can probably sell for $2200. So in a sense, this "only" cost me about $4600.

If you don't value your sanity, and decide to take on this project yourself, here are some ways you can save money.

- Borrow an engine stand from a friend - $122
- Don't waste money buying the Kent Moore Specialty Tools for Cylinder Sleeves; a shop will be able to remove the old sleeves, install the new ones, and bore/hone as required - $600
- Don't waste money buying the Kent Moore Balance Shaft Bearing Tools; unless yours are really worn out/destroyed, you can probably reuse the old bearings - $700
- Don't bother buying the appropriate Timing Tools (the ones needed to perform a Cylinder Head Replacement on this engine) - you would need these if you were simply removing and replacing a cylinder head on your engine, but if you're rebuilding it outright, you can get away without using any of these tools - $200
- Don't buy a dial bore gauge, as you won't need it if your shop performs all the boring/honing - $50
- Balance Shaft Repair; if you're careful and don't break one like I did, then it can save you...- $50
- If you are rebuilding an engine that currently runs, then it's unlikely you would need a new crankshaft - $700
- Don't waste money on a Duralast Serpentine Belt (something that I could not return after using) - $40
- If you can reuse your old starter, it can save you some money. At the very least, order one online for a much cheaper price. Mine cost me - $164.
- I did borrow an engine hoist/cherry picker from a friend; if you have to buy one, I would certainly try to return it and get your money back if able, otherwise this would cost you several hundred dollars.
- If you don't have to dremel/drill your 2008+ cylinder head for a 2006-2007 application, you'll save roughly $100. This is about what I spent on drill bits, dremels blades, etc. The drill bits add up quicker than you think.

Total Savings = ~$2726, which had I done, would have brought my total price down to just under $1900 (when taking into account selling the old engine). That looks waaaaay better on paper than the $4600 it cost me, and this is considerably less than the cost of a completely rebuilt engine.

**I'll update this list if I think of anything else **

Lessons Learned

**I'll update more as I see fit**

Cylinder Heads
1) The cost for a reputable shop to rebuilt my cylinder head was just under $600, but the quality of work was excellent. A second quote in my local area was around $500 (budgeting purposes)

2) Even though my vehicle is a 2007 year, and the donor engine was a 2008, both of them suffered from intake valve leakage, something that (should have) been fixed after the 2006 year models. The cylinder head shop I spoke to said the number one reason he rebuilds cylinder heads on these engines is due to valve seat failures and valve leakage. If anyone out there is reading this and is performing a (used) engine replacement, or is looking to buy an H3 outright, I would highly, highly recommend performing a leakdown test on the engine beforehand if possible.

Crankshaft
1) If your crankshaft needs reground/worked on, you will (likely) have an incredibly difficult time finding a shop to perform the work for you.

2) If swapping from a manual transmission engine to an automatic transmission engine, or vice versa, ensure that the crankshaft is correct on the flywheel side before you install the engine. Manual transmission engines should have a input shaft bearing, and automatic transmission models should have a metal insert (see pictures in the previous sections).

3) Aftermarket options are available. Heavy Duty Parts Company makes (what looks like) a fairly reputable replacement but the cost is high at over $900. Look for GM Genuine options online for the $700 range. I would personally avoid any off brands, but who knows, maybe all it takes is a little research to separate the good from the bad.

4) Crankshaft Relearn After Rebuild - Costs a pretty penny at the GM dealership if you have to resort to them. Unfortunately, a Zurich Scanner from Harbor Freight was not able to perform any of the system tests on the I-5 engine, which is why I went to the dealership. Some of the experts on here can chime in at which particular type, but you'll need a GM Scan Tool or a higher end HP turner to perform the crankshaft relearn yourself. My dealership charged me $200 for the relearn.

Balance Shafts
1) Can be disassembled with no problem, but the bolts are LEFTY-TIGHTY, RIGHTY-LOOSEY. Recommend applying a bit of blue thread locker to the bolts if you need to disassemble them for any reason.

2) If you cannot reuse your old ones, then you'll have to buy used ones online, because they are discontinued and are not made new anymore.

3) Balance Shaft Bearings - like I mentioned above, unless the balance shafts do not spin freely on the old bearings, could I do this again, I would not waste money on the Kent Moore tool that is required to remove/replace the bearings. Obviously I have less than 1000 miles on my new engine, but so far, the old balance shaft bearings are holding up just fine. Trying to remove these with a universal camshaft bearing tool did not work.

4) Do not pry these out by their flange, because they will break. See my earlier posts on how I fixed the problem (basically just bought a 2.9L balance shaft, disassembled it, and used the parts from it to repair the 3.7L balance shaft).

Misc.

Manifold Air Pressure (MAP) sensor is slightly different on a the 2006-2007 models, than the 2008+ models.

Crankshaft Position Sensor is different on the 2006-07 models, than the 2008+ models. The 2008+ models have three wires going to this sensor, whereas the previous years only have two.

Cylinder Sleeves / Boring / Honing - Take to a reputable shop. Do not buy the Kent Moore Specialty Tools.

The Final Question - Was The Whole Thing Worth It???

Well.......no, it wasn't. That's not to say it wasn't fun in some ways, that I didn't learn a lot, or that it wasn't incredibly rewarding at the very end, but given the choice, I would definitely not repeat this process again unless I was retired and had a lot more time on my hands, and if I had an actual shop to work in as well, where it wasn't 90-95F every day. Trying to rebuild this engine while working a full time job (as well as traveling a lot for my work as well), and also trying to be a husband (even without any children), I felt was incredibly, incredibly challenging.

In the end, my H3 does have a considerable amount more power than before, as well as slightly better fuel economy (~1-1.5 mpg increase), but in my opinion, this is a very small gain for as much time and effort as it took. If I could go back in time and perform this all over again, for the symptoms I was having (low power, less than ideal fuel economy, occasional P0300 codes, and compression loss of 30-40%), here is what I would do:

1) Purchase the Timing Tools Set for $200
2) Remove the cylinder head
3) Have it Rebuilt ($500-600)
4) Reinstall the head
5) Enjoy your vehicle

While this would be a challenging repair in itself, it is considerably "easier" than pulling the engine out and rebuilding the whole thing. This entire process took me approximately 4 months (look at the beginning of this thread, and compare it to now), where as a cylinder head repair would have maybe taken a month (if you consider the time it takes for the shop to rebuild the head). Had I done that, I'm confident the engine would have lasted another 50-100K miles before needing replaced/rebuilt and then I could look into replacement options. All in all, this would be a much cheaper and much more hassle-free repair than a complete engine rebuild.

If you love building engines, or just want to experience the process of everything, gain an appreciation for this terrific little engine, or maybe you just want your engine to experience a new life, then hopefully this entire thread will give you some insight as to what to expect, and also some ways to save some $$$ along the way.

If anyone has any questions about anything at all, feel free to reply here or hit me up in a PM; I'll be more than happy to discuss.

Hope everyone has a great day ahead, and keep on wheeling!

-Sam