Hello,
I tried to start 2021 off right with doing a water pump and thermostat change before the warm weather causes a real problem. The water pump has been weeping for a long while and it got bad enough to warrant changing. Before doing the swap, coolant could be smelled but never pooled and the thermostat gauge stayed pretty steady at 1/4 unless off roading in the mountains. After swapping the parts and filling the truck back up with dextron, the temp gauge is hitting halfway to 3/4. The fan runs at low engine speed and the coolant is full and has been burped twice. There is a soft sound kind of like a piston operated water pump off a farm that I have never heard before when the engine holds 1-3K RPM range. I am guessing pump cavitation would cause the new noise and it is much easier to hear in the cabin than standing in front of the engine. I have read other posts that other H3’s are running at around the 1/2 mark as a normal occurrence, but my truck isn’t regulating it there. I was hoping to improve cooling capacity as the engine gets hot here at high altitude when off roading.

I got the parts from advanced and there are no leaks, thankfully. I have plenty of hear in the cabin. Truck has 104k miles. I am trying to trouble shoot and figure out what to do next. Any help would be appreciated.
Thanks and happy New Year.

 

A few years ago GM raised the temperature of the thermostat for emissions reasons. All of the new T-stats run about 10+ degrees warmer now.

 

Find out what the actual coolant temp is with an OBDII reader.
Also sounds like you possibly have either a faulty new water pump or air trapped in the cooling system.

 

Welcome to HF.

MOVED to the H3 section where all H3 questions belong.

The new replacement T Stats are 5-10 degrees F warmer.
3/4 on the dash temp gauge is normal. It is about equal to an idiot light with a needle.

Question: did you fill the radiator with engine running cap off until up to temp? After that and driving it, you add to the reservoir tank to fill to correct level. There is no "burp" procedure for H3s, they just need to be filled correctly.

 

Sorry about the wrong placement of the post Doc Olds. Chalk it up to being a noob.

I did do a bleed twice with the filler cap off until the temp gauge needle was about the 1/4 mark. I even get it some gentle gas to see if I could rattle some air loose with the increased flow and a few blubbles did come out. Not enough to drop the level though. The overflow tank stayed filled with fresh fluid as I was leaking from the pump bad enough prior to replacement that I had to keep refilling it.

The information about the new temperature thermostat would definitely explain the thermostat’s new position. I will get an OBD-II reading on the truck on the way home today to see the actual temperature. The whole point of this was to make it run cooler going up pikes peak and now it runs hotter all the time. Facepalm.

I have put about 100 miles on it with a little mountain driving and it is has stayed slightly above 1/2 to 3/4 range. I’m building confidence but its still in the 20’s outside at altitude.

As a side note, it is probably not the pump that is making the new “thunk” noise I am hearing as pump and I am now relatively sure I removed all the air.

Thank you all very much for the advice. Is the sensor for the temp pre-radiator or after? I am trying to think if the readout I get tonight will help to see if the radiator is clogged. Its original to the truck.

 

The sensor is "pre" to the radiator. Btw, the radiator "is not original to the truck"!

 

X2
220° MAX temperature to prevent premature engine wear!
3/4 is 240°
My 3 runs 1/2 @ operating temp(200°), except on a hot summer day in traffic, may climb a tick above. Feedback with numbers from your "idiot" gauge:

 

Well, I plugged in a reader and looked at live data. I had to take pictures to keep it all straight.

After about 15 minutes of driving and a few idling in 46 degree weather my gauge stayed at this point.

The reader said 216 degrees.

I gave a little gas to bring idle up to 1500 and waited a minute or two. The gauge lowered to this point which is about where is is during normal driving now.

The reader said 203 degrees.

So pre-radiator temperatures are anywhere from 203-216 degrees after a gentle drive in the winter. Im guessing I will be above that 220 degrees with any kind of demanding driving.

And the radiator may have been replaced, that is true. The original owner kept pretty good notes on what repairs got done. Radiator replacement wasn’t listed but it still might have been done.

I’m dreading cracking open the coolant system again because of the mess. As I think about it, the truck ran cooler with the old thermostat but still got very warm (now I know >216 degrees) as I ascended big mountains. That maybe due to the power to weight ratio requiring the engine to work harder, or maybe the cooling system has been degraded for the duration of my year ownership.

Well either way I cant blame it on a water pump anymore... by process of elimination the radiator seems to be the only thing that is left to troubleshoot or upgrade. I still have the original thermostat as a backup. I appreciate the input and help from everyone. I will look into a radiator flush and price a replacement.

 

Clean the fins & recheck.

 

3/4 on the dash gauge is nowhere near 240F, and every H3 is different so the only way to know what the actual coolant temp is = scan it. The actual temp with 3/4 on your gauge will be different than 3/4 on the next guy's H3.

Wheeling in sand at low speed my 07 would climb to about 3/4, highest temp on my SCII = 221F. On the street the gauge showed just a tad over 1/2, about 198-200F with the replacement T stat.

Once I moved my 07 to an Efan conversion, the temp would get to about 205-210F and then pull down to 195F when the fan would shut off, which was about perfect. GM set them to run in the 195-205F range. Altitude and humidity will impact that a bit. Biggest impact is a dirty radiator.