The Limos.com Forum Has Moved!!!

One of our hummer h2 limos occassionally overheats, only occassionally. Bought it used with like 40k miles from another company. It ran fine all winter no over heating.

Now today it gets to 250 degrees we shut it down. Same thing last summer, maybe once a month it would get close to overheating. Today a/c in the front was kinda warm but cold in the back. Does this have anything to do with it? Also there isn't a coolant leak that is noticable as it parks in the same spot everyday inside. What do you think could be causing this? What can be done to solve this or help while we figure it out? We've had it to the dealer last year and they couldn't duplicate the problem nor figure it out.

My 165 Hummer use to over heat, or better put the gage said it was over heating when it actually was not.

The problem ended up being a faulty Wiring harness.

It would loose power and the back lights would flicker in the stretch section.

My Hummer never actualy got Hot! just every gage told me it was. Turned out to be an easy fix by replacing the harness connectors.

Heres what I have planned so far, tell me what you think:

1. 160 degree "fail safe" thermostate for hummer h2
2. full coolant flush, going to wash out the inside hoses with a hose
3. single aux fan I believe its 9 inches or 7 inches for in front of radiator on h2
4. double aux fan for behind the radiator to blow into the engine for engine cooling
5. Water Wetter, used to add into coolant of engine to help run coolant cooler, buy 2 bottles

I'd say NOT to remove the T-stat, it could make your computer go nuts and make the car do odd things. Everything is computer controlled these days, try something that the system doesn't like and the system will compensate for it elsewhere.

I think it's time to find a specialist on this one, nothing sounds like it's working to fix the problem. I'd bet it's a sensor somewhere not sending the right signal and the system is compensating with the wrong results.

You need to get your A/C system looked at. Most likely your condenser is not performing as it should. I dont know hummers but if its like any car I know, if the condenser is stopped up it will heat up your radiator.

quote:

Originally posted by First Class Limos:

Would it be ok to completely take out the thermostat for the summer only and put one back in, in the winter? Would this help?

It should help but its only a band aid. Engine will stay in open Loop mode and it will burn a lot more gas than it should.

I noticed our SUVs try to overhead only if standing still in 100' weather with all the power (AC, fans, etc on). But only if its really really hot and no cold air flow coming in.

What happens when you shut the power off to the back when it starts overheating? Does it cool off?
Try installing a high idle switch, that should have the fans spinning better and start cooling.
But its only a band aid.

Do you have 2 compressors?

We have replaced the thermostat like 5 times. Last time we put a fail safe in it, so if it does overheat (remember its a limo and it does alot of idling at wedding and when 25 people are getting out) the thermostat will stay OPEN. Its not the thermostat.

Would it be ok to completely take out the thermostat for the summer only and put one back in, in the winter? Would this help?

But we have 5 h2's and this is the only one that has this problem.

What we plan to do is complete coolant flush, then install extra aux fan in front of the radiator, and 2 aux fans behind the radiator blowing towards the engine.

We put a new radiator and fan on the h2 last year, cant remember if we did the water pump. Could the water pump cause it? Last year we thought it was a leaky head gasket and we ran some sealant in there, and it didnt overheat since then because it didnt overheat all winter, then bam it did it again today.

Trying to get as many ideas to check as possible. Any suggestions?

Yes coolant level is high, not even leaking coolant. Its been doing this speraticly over the couse of a year, but never over winter.

Did you check coolant level?