Thermostat

AFD256 · August 29, 2007

How do you know if your stat is bad?

Draenor · August 29, 2007

They are designed to stay open when thay go bad. Easy way to find out is watch your coolant temp guage. With the engine cold, rev it up a bit in the driveway and to get the engine to operating temp. The guage should climb to about 180degrees and then drop a bit. That is when the t-stat opens. If you never get there, the t-stat is stuck open and needs replacing. And of course if the opposite happens, you definatly have a bad t-stat or a clog in your cooling system.

AFD256 · August 30, 2007

Well this is what's going on- Start up is normal, warms up to the normal temp and and you start driving it shoots up to the red line with the "check eng temp" on the display. Is it the thermostat? Waterpump drive belt?(how/where is that and how do you check that?) What else could it be? I had the coolant changed 5,000+ miles ago and it still looks/smells good and test out okay. The upper radd. hose is hot if that means anything. Any help is greatly needed/appreciated. I Think I will attempt to change it out tommorrow, It's a 01 4.8L, any tips?

Thanks in advance

Chris

AFD256 · August 30, 2007

Helloooooooooooooooooooooooooooo.

C & A s Dad · August 30, 2007

Your stat is likely stuck closed not allowing circulation. If you want to drain the coolant to a level below the stat using the drain cock in the radiator, it will make your job a little neater.

Clean the surface good and make sure you install the bolts by hand and tighten them a little at a time. If the stat housing gets out of alignment with one bolt too tight before the other, it will bust the housing.

Other than that, I cannot think of any other tips for this job.

You will read several of my post concerning Lubegard's Kool It product. This is an excellent cooling syst additive that will eliminate all Chemical Electrolysis. Great product that we sell a lot of and it is recommended by by Modine radiator co.

AFD256 · August 30, 2007

Thanks pop, do you think it could be anything else?

waynet · August 30, 2007

ive allways removed it when in dout , put it in a pot of water, then boil it.

i use my hotub thermomiter and watch to see when it opens, then i know where or not it was the problem for sure, just something i do to see how things work, and it does

AFD256 · August 30, 2007

Well I changed it this am, called the local dealer-54.00+/labor and 56.00+for the thermostat=$110.00. went to autozone, 21.00 for the stat. Took about a hour, I took more out than I had to, gave me alittle more room. Not as bad as I thought. For future refence how do you COMPLETELY drain the coolant? I pulled the stat and more coolant spilled out. I endend up jacking the side of the truck to tilt it away. And the filling process is alittle weird.

Oh and it did clear up the overheating

Draenor · August 30, 2007

there is a drain petcock on the bottom of the radiator. Glad you were able to fix the problem. It is unusal that the t-stat stuck closed. As I mentioned before they should fail in the open position. Though I have seen one or two stick closed.

C & A s Dad · August 31, 2007

John, you are right, they typically stick open but we do see them stuck closed as well. The boiling water test is a good way to see if it is opening.

Chris to drain it completely, you would have to remove a plug from the block. I would have thought draining the radiator would have removed the coolant to a point below the stat. Guess not in your case.

Hey, happy this cured your problem. By the way, that POP comment made me mad. Not really, it actually put a big on my face.