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Hummer H3For the Hummer driver who wants the rugged look and off road capabilities of the Hummer, but in a smaller size and with a more fuel economy friendly engine.
How are y'all saying the temp gauge is an idiot light with a needle and to just ignore it, yet still reference 3/4 or 1/2 being normal? Is it an idiot light or not?
How are y'all saying the temp gauge is an idiot light with a needle and to just ignore it, yet still reference 3/4 or 1/2 being normal? Is it an idiot light or not?
You said outside temps over 100F. You seem to be aware that would result in higher then normal coolant temps, so add 10F to the normal coolant operating range and you would still be OK. The system was set up for expected ranges of outside temps, plus margins for extremes. Over 100F is extreme, it never gets that hot in most of the country. Your engine is not going to melt down over 10-15F heat load.
The TStat is at the Radiator Inlet side,(#954 in 305) which is outlet of coolant from the engine, so it is acting on the engine heated coolant. It stays closed at start up to build engine temp rapidly until warm enough to begin to open and allow flow out of the engine back to the radiator. Your upper radiator hose is the outlet from the radiator heading into water outlet (#308) into the engine to the water pump (#300) at the front to be pushed through the engine/system.
The gauge gets its feed from the ECT, but just points and does not display actual temp. It is located at the back of the block to measure engine heated coolant. #9 below.
A scan tool displays -38°F to +284°F. The Engine Coolant Temperature (ECT) sensor is mounted in the coolant stream. The powertrain control module (PCM) applies 5 volts to the ECT sensor circuit. The sensor is a thermistor which changes internal resistance as temperature changes. When the sensor is cold (internal resistance high), the PCM monitors a high signal voltage and interprets it as a cold engine. As the sensor warms (internal resistance decreases), the voltage signal decreases and the PCM interprets the lower voltage as a warm engine.
None of this measure the coolant exiting the radiator, which is always significantly cooler than what is inside the block. How much, 10-25F cooler always. Obviously, it has to "cool" the engine, or the system would not keep temps under control. I have a digital temp controller on my SFan4500 Efan that operates on the outlet side of the radiator on my 09 Alpha (not an I5 but near identical radiators and locations and more motor making heat) and it is always 15F + cooler than the actual ECT numbers.
Whether the TStat is at the top, or bottom, doesn't matter, the cooling system is till doing the same thing. None of this mentions the PCM's role in maintaining temp either. Get those panties out of the wad and relax for the big picture instead of staring at an idiot light with a needle.
you have alpha, we have i5. they are completely different engines. and a different cooling system. don't confuse. i5 idiots made the cooling system.
Idiot light with a needle aside. I think everyone in this thread can agree that gauge is not accurate. We're talking about H3 running hotter than 215F which has been suggested over and over to be normal, when it's not. GM introduced the new hotter t-stat for better emissions but at what cost to the vehicle? Sounds like a case of typical corporate bureaucracy, make someone in some department happy and move along.
I used a scanner to monitor mine and gotten to 227 at some points, which would be even hotter if I shut the engine off, not good. I literally went down the list and checked everything. I was puzzled by the location of the T-stat which is situated after the radiator at the engine inlet. Why would it be placed after the radiator? I took mine out and car doesn't run hotter than 215F, which seems to be within normal range now. So go figure, a lot of good information on this forum and I see you Doc repeating yourself a lot.
The ECT sends the same signal to the PCM & GAUGE! When using a scanner, you get the same signal sent to your gauge. With an
you can check temp on the passenger side of the cylinder head and compare with your ECT scanner reading. Relocating thermostat will NOT stop OVERHEATING!
The ECT sends the same signal to the PCM & GAUGE! When using a scanner, you get the same signal sent to your gauge. With an IR GUN you can check temp on the passenger side of the cylinder head and compare with your ECT scanner reading. Relocating thermostat will NOT stop OVERHEATING!
Taking the thermostat completely out on mine helped, how do you explain that? I am relocating the t-stat for a few different reasons:
1. So I can run a cooler 170-180 T-Stat.
2. So I can have easy access to the T-stat and swap out to a warmer one during the winter if needed (I cut my arms up getting to it yesterday, don't want to do this often)
3. So that the T-stat will be located at the engine outlet/radiator inlet and react to engine coolant temp not radiator coolant temp. Wouldn't that be the case?
I'll look into doing the engine enema also, won't hurt. Thanks for the tip and link.
Taking the thermostat completely out on mine helped, how do you explain that? I am relocating the t-stat for a few different reasons:
1. So I can run a cooler 170-180 T-Stat.
2. So I can have easy access to the T-stat and swap out to a warmer one during the winter if needed (I cut my arms up getting to it yesterday, don't want to do this often)
3. So that the T-stat will be located at the engine outlet/radiator inlet and react to engine coolant temp not radiator coolant temp. Wouldn't that be the case?
I'll look into doing the engine enema also, won't hurt. Thanks for the tip and link.
I never relocated my t-stat, yet I did replace the OEM. That makes 2, in 16+yrs. My PM(preventive maintenance) includes fluid changes,(mostly premature), the coolant system received new DEX-COOL, many times, less than the 5yr recommended interval. I never had to flush coolant system.
Old coolant could cause blockage in the coolant system restricting flow causing OVERHEAT.
Btw, you can't come up in here touting your issue with the I5, it's gibberish!
I never relocated my t-stat, yet I did replace the OEM. That makes 2, in 16+yrs. My PM(preventive maintenance) includes fluid changes,(mostly premature), the coolant system received new DEX-COOL, many times, less than the 5yr recommended interval. I never had to flush coolant system.
Old coolant could cause blockage in the coolant system restricting flow causing OVERHEAT.
Btw, you can't come up in here touting your issue with the I5, it's gibberish!
what do you mean? Isn't this H3 section, not sure I understand. Anyway, thanks for the input.
you have alpha, we have i5. they are completely different engines. and a different cooling system. don't confuse. i5 idiots made the cooling system.
I had an 07 for 12 years, changed 3 radiators, the T stat, and modified it to run an Efan. The H3s all have the same radiator, nearly identical shrouds, and same AC condensers. My point being, if that system can cool a V8, it can surely handle the I5, and does.
The ECT sends the same signal to the PCM & GAUGE! When using a scanner, you get the same signal sent to your gauge. With an IR GUN you can check temp on the passenger side of the cylinder head and compare with your ECT scanner reading. Relocating thermostat will NOT stop OVERHEATING!
Look, at third grade level. The gauge is not accurate, it does NOT display any temp reading. The gauge just points. Red means HOT. If it points to Red, the cooling system is HOT. Otherwise it is all good. That is what it means and all it means.
If you put 10 dash clusters in the same H3 and drove it to operating temp each time, each of those gauges would be pointing to a different place. Some where in the middle to 3/4 range, yet they all would be receiving the same ECT information and pointing to a different place. The moral of the story is, scan it for actual temp BEFORE making any conclusion about what you think the gauge is telling you and that is why 3/4 is as NORMAL as 1/2 or anywhere in between.
