Truck Running Hot

[smitham]

I just got a 97.5 about 2 months ago and have been fixing things as they go, but I seam to have another issue that discovered yesterday. The truck is starting to run hot!!! I drove it on the highway this weekend (to and from off roading) and it stayed at the normal 195 the whole time.

Well yesterday the truck started running hot on the highway it got to about 218 +/-. So when I got home at night I washed out the cooling stack. There was mud in there but when I was done clean water was running out. I again had to drive on the highway today and the truck again got hot. This time it got up to 220 - 230, but at least a good thing is that it did not get hotter than that in bumper to bumper traffic (1hr to go 16 miles).

So what is my truck's problem? Is it the t-stat, fan clutch?

[BlueHUMMERH2]

From the Hummer Knowledge Base:

Checking fan clutch:

1. Check for excessive bearing play. Using fingers only, press tip of fan blade toward and away from engine. Tip of blade total movement should not exceed 0.20 in. (5.1 mm). If movement is more, replace fan drive.

2. With engine off and ambient temperature of 50F (10C) or higher, fan should turn evenly with noticeable drag. If fan turns hard, very easily, or with uneven resistance, replace fan drive.


Dave on temp differences:

There was a lot of comparison of temperatures between owners, with some owners becoming concerned that their trucks were different than others. The gauges are not all that accurate, so these comparisons didn't mean very much anyway, but they did cause concern among owners.

Because of this (and other reasons), AMG changed the gauges in the later trucks so that no "actual numbers" were on the gauges.

The most important thing is to get accustomed to how your truck behaves, and watch for changes in that behavior. As long as your temperature reaches a steady level, and only goes above that when the engine is working hard, you have little to worry about as far as "engine temperatures" are concerned.


Continue to monitor your temperature and check the fan clutch. From what I've read, the temp may go up to 220-230F before having the fan engage. Perhaps you're experiencing the increase in temperature because ambient temps have been increasing on the way into Spring.

[ssgharkness020147]

Start by replacing the T-stats (there are two). Napa has the best prices at about 11.00 a piece. If that does nothing for you check the fan clutch and make sure it is good, if you went through any deep water off road while the clutch was enagaged you very well could have fried it, Lynch HUMMER will have the best price on a new one. The cooling stack could be all gummed up with crap, the only way to REALLY get it clean is to disassemble the stack and pressure wash everything individually. Other then the water pump could be going out, but I would do the t-stats and check the fan clutch before you start digging in to the mess of a water pump replacement.

[smitham]

I followed a friends advice and checked the fan clutch first. According to an article on flash off road if you turn off the truck and the fan still turns then the clutch is bad. Well I did this test and the fan kept spinning.

I went to the local parts store to get a fan clutch and they didn't have any in their system. I had them pull up a 97 3500 4x4 truck with the 6.5 TD. and they had one. I got the new clutch home and it is the exact same. after the replacement I did the test again and guess what the fan stopped. Looks like this was the problem.