I am new to being a member but I have used this amazing website numerous times since purchasing my 08' 3.7L Hummer H3! I have always dreamed of having a hummer and finally saved up enough to get mine in 2012. Unfortunately I was driving down the highway when I lost full throttle power and the engine stopped. Since that day seems like a nightmare I cant wake up from.

A little history: I have had very few issues with this vehicle and seriously love it!! In 2014 I had a cracked radiator and had it replaced. 2016 I started having the dreaded thermostat issues took it to dealerships/private shops no one could figure it out so they replaced the thermostat (which didn't help the problem). Dealership said they thought it was a computer malfunction and just to let it be. I did that and never had any further issues from it.

August 22nd 2017- Please keep in mind there was no issues or noises or anything noticeably wrong or acting up with the Hummer. I got an oil change on the 19th, everything seemed great. Morning of the 22nd I woke up and started my drive to work from exit 77 to exit 94. I started to exit and the gas peddle had 0 power! There wasn't any warning or safety indicators on the screen and everything still had full power. There was no smoke, no weird noises, the only thing I found was underneath it looked as if there was a small oil leak.

This the dealership write up:
"Initial diagnostic was complete lack of compression. We did a cylinder compression test and the truck was showing between zero and ten pounds. A cylinder leak down test showed that it was leaking compression into the cooling system, which was also completely dry. This lead to the cylinder head gasket diagnostic. It was after we had started preparing to reinstall the cylinder head(cleaning off carbon/the sludge made by the coolant in the cylinder) that the hole in the piston was noticed. What condemned the engine, as opposed to just installing one new piston and ring set, was the damage to the cylinder wall cause by the piston material being embedded in the cylinder wall essentially rendering the block un-usable.
The waterpump and thermostat(which only comes with the housing, go figure) were going to be replaced because anytime they get that hot the thermostat stops opening/closing at the correct temperatures, and the waterpump bearings and seals tend to be destroyed."

At this point I really dont care to put another 3.7L in the Hummer. I am trying to view this as a positive and take the opportunity to put a badass engine in! Any suggestions/recommendations would be great! I can only spend around 4-5K on this.

Thank you everyone so much and I apologize if my terminology isnt correct and for the post being a novel!

 

Dealer mechanic suggested:
"The LS series V8 swap (which is awesome). This is actually not -that- hard of a swap, it is of course extremely time consuming. But the aftermarket has solved most of these problems for you as the V8 swap into the Colorado is extremely popular. GM did install the 5.3 into the Hummer H3 Alpha and into the Colorado/Canyon. This means that things like engine mounts, accessory drive, manifolds are available from GM and from the aftermarket.

This is not a complete list but things that I know will need changed/addressed are:

Transmission - different bell housing.
Engine mounts
Exhaust manifolds
Accessories and drive (alternator, a/c compressor, etc.)
ECU and harness

Do some research, because the Silverado/Sierra 5.3/4l60 combo out of the 2003 to 2007 (I believe) can be had for a pretty reasonable price and you can get the entire harness/ECU and most of what you need for the swap."

Advice?? Anything and everything helps at this point!

 

New here! So sorry if this is the wrong section but I read through alot of other forums but I am still needing some help!

Alrighty yall I am working with an 08' Hummer H3. Currently have it all taken apart from the dealership doing their diagnostic. Results=full engine replacement!

A mechanic friend suggested looking into just swapping the engine and suggested a LS series V8 swap?

I am totally open to suggestions but am working with about 4-5K total. My grandfather has a shop and I am hoping to have my husband do majority, if not all of the labor.

thank you in advance for your time and help!!!!

 

I went through this at around 210k miles. A full engine swap for an original crate engine from GM cost me about $4800 installed. Stick with the original engine.

if you move up engine size, particularly the v8, plan to purchase a new transmission or convert yours to handle the new engine and all the labor involved with that. Further, you have to buy a new computer for the car to run a hummer with a v8. All told, I was quoted around 8k to do the conversion, which is probably even more now.

 

Hi, there is quite a bit more to it than your dealer mechanic hinted to.
Computer issues (ECM/TCM/BCM), wire harness modifications, added sensors, motor mounts, exhaust, torsion bars, ALL accessories and brackets, trans pan and oil pan to just to start. The Alpha H3s use a complete aluminum assembly, block and heads to save weight out front (LH8/LH9).

Please read about engine swaps on H3 i5s to V8s.
There are 4 that I know of that are fully completed without any issues at this time.
The others are still working the bugs out.

You said you have a 4-5K budget in one of your posts. If you can get the complete job done for that kind of $ that would be a great deal and go for it. Just have all of your research done before you start! Good Luck.

 

A regular LS is not a direct swap, you need an LH8 or LH9, or use the oil pan from and LH motor with the LS. It will end up running you about double your budget unless your hubby does the work to install a used motor and keep you fingers crossed that the used motor doesn't puke after a ton of labor and all the work-arounds.

The automatic transmissions are the same for all H3s: I5s and V8s. You would need a PCM re-tuned/programmed for the V8.

 

Seems to me like it would be greatly simplified by using an engine/trans from an 08/09 GM since the electronics would then be the same generation. Trying to get the prior generation computers to talk to the remaining new generation ones (you will be needing to keep a LOT of them like BCM, DDM, PDM, etc) would add a significant layer of extra complexity I'd think. The new generation uses a different communications than the older generations. At least in the full size trucks anyways. I'm really not all that familiar with the H3's personally though and maybe it will not make any difference in the conversion.

 

I converted mine to LS3. See thread below. https://www.hummerforums.com/forum/h...monster-38707/ That said, I have my old I5 sitting here looking for a new home. It's got 110k miles on it and it was running good when I took it out...

 

Do you still have the I5 laying around and if so where are you located. Kind of hard to find a new crate motor and I just blew mine this morning.

 

Sorry but mine is long gone. Good luck with your search.