I have a 2002 Hummer H1. Overall, its in great shape and runs fine.

I do have an issue with cooling. The truck seems to run a bit warm, shows the needle just to the right of center on the gauge, mostly driving in traffic or rolling over 65 on the highway.

What kind of radiator fluid should I be using? The regular Prestone green stuff is what I use in all my other vehicles.

What is the ratio of fluid to water that I should be mixing?

Any help would be appreciated....I have searched and couldn't find what I was looking for.

Thanks!

 

190 -200 is the normal operating range. If you are running up long or steep inclines, especially with AC on it will run up to 220 or so unless you slow down to approximately 55 mph. Normal green antifreeze is fine.

 

I live and drive in South Texas. If you stand on top of a beer can, you can see Oklahoma. (No inclines here).

Mine fluctuates halfway between the 1/2 hashmark and the 3/4 hashmark....not exactly sure what temperature that is, but I think it is over 210.

My neighbor is a mechanical engineer. He says that if the cooling system is working properly, it should never really move above 190 if it is working properly.

I keep telling the dealer that it isn't right, but they keep saying it is OK and that their techs are H1 certified.

I can't argue, as I am just a lay-person when it comes to auto mechanics.

Any input is appreciated. Thanks for the first reply!

 

The halfway mark is 200 degrees. Your water temp needle should be there during most normal operation of the truck. Inclines will cause that temp to rise. Running the AC will also. 3/4 on the guage is about 225 or 230 degrees. That is about as hot as you want it to run but still within the operating parameters. The gauges are not particularly accurate. You may want to hook up a scan guage II and check the guage reading compared to the scan guage reading. At what speeds does the truck heat up?

 

the correct operating temp for a Hummer H1 turbo diesel is 0-240 degrees. i was told this 13 years ago by am general. that is the reason they changed the gages to ones with no numbers on them because people always thought that the vehicles were running hot. the fan clutch comes on at 210-220 and will mostly maintain the temp in that area. common sense is to slow down if it gets close to the red and let it self cool down. our race car runs 220-240 every race and has never overheated on us.

 

Have you put a pressure tester on the radiator fired up the truck and watch the pressure build up to see what you dealing with. Whether it builds up rightaway, surges, or what the pressure actually is.

 

Hummech is right of course.

The military is in the same boat. The armored heavy HMMWV's in Iraq have changed their turbo diesel documentation and PM requirements that their trucks is ok for operation to 240 degrees before they are flaged for NMC[not mission capable]

During normal/light operation my truck is 190 degrees driving on level ground at 65mph. If I go faster than that in hot weather then I may go up to 200 degrees.

The only times I got it up to 220-225 was on very steel long inclines going up highway 5 on that long crawl to Gorman/Hungry Valley or climbing up 15 towards Barstow. Dropping to 55mph and/or turning off A/C will drops temps to the 200 range.

Not to mention the gauges are pretty low quality on our truck. The water temperature guage is an analog unit that runs off a single wire on the front drivers side of the block. The digital sensor is inline with the coolant passage and is much more accurate [the computer reads data from this]. You can't view that data unless you have a scan tool.

 

Add redline water wetter to the system. It will help lower your temps.

Nick

 

Get plain stock radiator and run it with the 2 fans. If you cant keep the car cool with that then there are other problems. I bet your current one is all corroded and clogged inside from tap water and the finds are beat up with crap stuck in them.

 

When I open the radiator cap, it as clogged up with rust particles and dirty crap. I want to clean it out, I do not know where is the plug to loosing out of the radiator. How do you do that , anyone knows?