2006 Hummer H3 over heating to 3/4 when parked.
#11
07-03-2018, 01:11 AM
Wrong
Apparently we need to learn you how a cooling system works.
First, 3/4 mark temps are not overheating to begin with. Overheating is when the needle is in the red.
1) When your motor is running your water pump is turning and circulating coolant through the radiator and motor, passed the temp sensor which is reading the temp of the coolant exiting the motor at the head. The radiator cools the fluid from the motor by air heat exchange cycles through the motor which heats it. This is a continuous cooling cycle.
2) When you shut off the motor, what happens? The water pump stops and so does coolant circulation. Hence, the sensor is now in coolant within the head that is not moving and experiencing a rapid climb in temp because it is direct contact with the motor/head and not being flushed with cooler fluid from the radiator. The cooling cycle has stopped. You turn the key on a few moments later and what do you see? Higher temp than when you shut it off because of "heat soak."
Start the motor and and that starts the cooling cycle, go back to #1. The temp decreases after a few minutes.
So what you have observed is completely normal for every water cooled automobile.
Get a scan gauge or borrow one. The dash temp gauges are not highly accurate so you have only an idea of what the actual temp is, and for most applications that is all the operator needs. It is almost like an idiot light with a moving needle. BTW your DIC will display "ENG HOT" when your H3 starts to overheat. If you had the AC on when it begins to overheat, the AC will shut off before the temp triggers the DIC display.
The actual temp at the 3/4 mark is about 212-218F depending on your particular truck's gauge accuracy, plenty of room before an overheat. When I turn my 3 off and the actual temp is say 190F (1/2 on the dash gauge), in about 10 seconds if I turn the key to on, it will read 204F. All of which doesn't matter because with the engine off, everything is beginning to slowly cool, no more heat is being made.
FYI: 50/50 water and Dex-Cool has an open boiling point of 228F (in an open pot, no pressure) and in a pressurized cooling system @ 15PSI, 265F.
First, 3/4 mark temps are not overheating to begin with. Overheating is when the needle is in the red.
1) When your motor is running your water pump is turning and circulating coolant through the radiator and motor, passed the temp sensor which is reading the temp of the coolant exiting the motor at the head. The radiator cools the fluid from the motor by air heat exchange cycles through the motor which heats it. This is a continuous cooling cycle.
2) When you shut off the motor, what happens? The water pump stops and so does coolant circulation. Hence, the sensor is now in coolant within the head that is not moving and experiencing a rapid climb in temp because it is direct contact with the motor/head and not being flushed with cooler fluid from the radiator. The cooling cycle has stopped. You turn the key on a few moments later and what do you see? Higher temp than when you shut it off because of "heat soak."
Start the motor and and that starts the cooling cycle, go back to #1. The temp decreases after a few minutes.
So what you have observed is completely normal for every water cooled automobile.
Get a scan gauge or borrow one. The dash temp gauges are not highly accurate so you have only an idea of what the actual temp is, and for most applications that is all the operator needs. It is almost like an idiot light with a moving needle. BTW your DIC will display "ENG HOT" when your H3 starts to overheat. If you had the AC on when it begins to overheat, the AC will shut off before the temp triggers the DIC display.
The actual temp at the 3/4 mark is about 212-218F depending on your particular truck's gauge accuracy, plenty of room before an overheat. When I turn my 3 off and the actual temp is say 190F (1/2 on the dash gauge), in about 10 seconds if I turn the key to on, it will read 204F. All of which doesn't matter because with the engine off, everything is beginning to slowly cool, no more heat is being made.
FYI: 50/50 water and Dex-Cool has an open boiling point of 228F (in an open pot, no pressure) and in a pressurized cooling system @ 15PSI, 265F.
UMM False, I have the same symptoms as all the other Hummer people on here. I can tell it's running too hot because I can smell the Radiator fluid which is caused by it bubbling and being too hot. I'm changing out the thermostat again, but this time with one made for the Alpha. This problem started after I purchased a new Radiator after mine broke, so it's either a bad radiator or the wrong thermo. Stop telling people it's not running too hot or it's a gauge that's wrong, because you are wrong.
#12
07-03-2018, 06:52 AM
If you smell fluid it is not because it is overheating. The gauge in the dash is a glorified idiot light. Get a scanner to assess the true engine temperature. If your coolant is "bubbling" your H3 would have gone into "A/C OFF" and limp mode. Even in the "A/C Off" overheat protection mode I have never smelled coolant. Sounds like you have a pinhole leak somewhere after your radiator swap.
You may also have an air bubble trapped in your system causing it to overheat. Not sure what advantage you think an Alpha thermostat has...
You may also have an air bubble trapped in your system causing it to overheat. Not sure what advantage you think an Alpha thermostat has...
#13
07-03-2018, 08:54 AM
UMM False, I have the same symptoms as all the other Hummer people on here. I can tell it's running too hot because I can smell the Radiator fluid which is caused by it bubbling and being too hot. I'm changing out the thermostat again, but this time with one made for the Alpha. This problem started after I purchased a new Radiator after mine broke, so it's either a bad radiator or the wrong thermo. Stop telling people it's not running too hot or it's a gauge that's wrong, because you are wrong.
As Tainter said, if you smell fluid, then there has to be a compromise in the system, pin hole - small leak. More importantly, you need to look at the actual temp with a scan gauge of some kind, then you will know what the temp is and not be guessing. Read the temp and feel free to post it here.
Let's review the three layers of H3 overheat protection: The H3 will first shut off the A/C if it was on and display "AC OFF" in the DIC; then if temp still rises, display "ENG HOT" in the DIC and chime (ding, ding, ding); then if temp does not fall, go into Reduced Power, all before reaching an actual overheat situation at 260F +.
If you never saw any of those messages, not too hot and not an overheat.
BTW, the new T Stats are 5F degrees hotter than the prior factory installed units, so you will see the idiot gauge point to a wee bit different spot after swapping out to a new T Stat.
#14
07-06-2018, 04:24 PM
UMM False, I have the same symptoms as all the other Hummer people on here. I can tell it's running too hot because I can smell the Radiator fluid which is caused by it bubbling and being too hot. I'm changing out the thermostat again, but this time with one made for the Alpha. This problem started after I purchased a new Radiator after mine broke, so it's either a bad radiator or the wrong thermo. Stop telling people it's not running too hot or it's a gauge that's wrong, because you are wrong.
Anyway, my 06 H3 has been at 3/4 gauge 9 months a year for the past 12 years. According to the scanner, thats around 208*.
Im at 115K miles right now.
GM decided to fix this by "fixing" the needle on the newer trucks. On my 09 Alpha, the needle will stay pegged a hair below half between around 185* all the way till 224*. It will finally be half at exactly 225* and stay there. I once hit 240* and it was still at half. If you google around you will find this to be common on different GM platforms (colorados, trail blazers...)
#16
09-24-2018, 09:01 AM
If your temp gauge reads 1/2 -3/4, ain't nothin to fix. Drive on weed hopper.
#17
03-29-2019, 01:08 PM
H3 showing higher temp
My question is, if it's not over heating at the 3/4 mark, why did it go higher after 12 years of running at 1/2 mark? Also, shouldn't there be a change in the reservoir? We have replaced thermostat, radiator, temp coolant sensor, fan clutch and a couple of freeze plugs and nothing has changed the level of the reservoir. And, we somehow got green antifreeze this last time, but it's still orange at temp sensor and reservoir. Just don't understand. At least I don't smell it anymore.
#18
03-29-2019, 01:55 PM
My question is, if it's not over heating at the 3/4 mark, why did it go higher after 12 years of running at 1/2 mark? Also, shouldn't there be a change in the reservoir? We have replaced thermostat, radiator, temp coolant sensor, fan clutch and a couple of freeze plugs and nothing has changed the level of the reservoir. And, we somehow got green antifreeze this last time, but it's still orange at temp sensor and reservoir. Just don't understand. At least I don't smell it anymore.
Brand new trucks will always run cooler than a ____ year old identical truck with 100K miles. Why do auto transmissions die? They eventually get too hot.
When I was a learning to drive 49 years ago.... they taught you that overheat is when the temp need is in the RED, not before that.
#19
03-29-2019, 05:02 PM
I would not drive my vehicle if the temp gauge hit 3/4 unless I ruled out the fact that the gauge was inaccurate. Use a scanner, infrared thermometer, etc.. to find the actual temp. IMO, 210 is the optimal temp. The coolant system is designed to keep the engine at a near constant temperature. If the temp is to cold it affects fuel economy and performance. If the temp is to hot, engine/trans parts overheat and get damaged. When my '07 was operating 1/2- 3/4, I replaced the T-stat and installed fresh coolant. Now 12yrs old and it still stays at 1/2 or slightly above/below that mark. Btw, always make sure the radiator fins are clean, spray them with a garden hose on high pressure, to clean out any debris.