Engine keeps overheating

**bigpapa53023** · 10-14-2008

I am in desperate need of help. Engine temp goes all the way up and then drops off suddenly to normal and the repeats. I thought that the themostat was sticking so i replaced it and it seemed fine for a day and then was back to doing the same thing. I thought that maybe i had a bad t-stat so i got another one and while i was changing it I noticed that the LIM was leaking so i replaced that and put in a new water pump as well thinking that i fo sure had this problem nailed. Took it out on a test drive tonite and what do you know IT STILL OVERHEATS SND THEN DROPS OFF. Some times it will stabilize after one or two trips up and down the scale but most of the time it just keeps doing it. Some times it goes all the way up into the red and the temp light comes on and sometimes it drops off just before that. Oil is not over full adn i dont think thats where its going. Coolant level seems stable after LIM replacement. My thought are a possibly clogged radiator. Oh and by the way lower and upper hoses do get hot. PLEASE HELP!!!

**SyntheticShield** · 10-15-2008

At first I thought too you perhaps had a bad thermostat, but since you have replaced that along with the water pump and you fixed a leak in the LIM Im thinking its one of a few things that come to mind.

1. You got a clogged radiator. But having said that, its not typical of that issue to suddenly normalize coolant temps. With a clogged radiator I would expect temps to climb or creep up and stay there.

2. Your electric fans are not turning on soon enough. I suspect here, if your 3.1 fans are like my 3.8 fans, then they have two stages and the first stage is not engaging and when it reaches the higher temp range the higher speed fan is kicking in and dropping temps.

3. The other possibility is that perhaps the radiator cap is bad and is not allowing the system to pressurize. But I would suspect you would be seeing some coolant leaking somewhere around the coolant overflow or something like that or around the cap itself. Look for a white to greenish crusty build up somewhere, thats likely a leaking point.

4. You got a leak somewhere else that is preventing the system from pressurizing. I dont know if coolant is ran through the throttle body on that engine like it is on the 3.8, but if it is, then a throttle body gasket failure or leak could cause that to some degree.

Those are all the things that come to mine now. Hope it helps.

**nutcase** · 10-15-2008

enemas never hurt :P

**Blown97** · 10-17-2008

Originally Posted by SyntheticShield

At first I thought too you perhaps had a bad thermostat, but since you have replaced that along with the water pump and you fixed a leak in the LIM Im thinking its one of a few things that come to mind.

1. You got a clogged radiator. But having said that, its not typical of that issue to suddenly normalize coolant temps. With a clogged radiator I would expect temps to climb or creep up and stay there. True, however just in case I would get some radiator flush and do a flush

2. Your electric fans are not turning on soon enough. I suspect here, if your 3.1 fans are like my 3.8 fans, then they have two stages and the first stage is not engaging and when it reaches the higher temp range the higher speed fan is kicking in and dropping temps. I would bet that this is your problem, you should be able to test it using 2 ways: 1 turn on your A/C, the fan should turn on, 2 wait until your engine heats up at idle and see when the fan turns on.

3. The other possibility is that perhaps the radiator cap is bad and is not allowing the system to pressurize. X2, replace the cap, even if it is not the issue it is cheap maintenance But I would suspect you would be seeing some coolant leaking somewhere around the coolant overflow or something like that or around the cap itself. Look for a white to greenish crusty build up somewhere, thats likely a leaking point. This would be if you are using the green A/F, if you are still using Dexcool it will more of a red or orange in color crusty build up

4. You got a leak somewhere else that is preventing the system from pressurizing. I dont know if coolant is ran through the throttle body on that engine like it is on the 3.8, but if it is, then a throttle body gasket failure or leak could cause that to some degree. Coolant does run through the TB but not through the TB gasket like the 3800's, there are 2 little hoses that connect the intake manifold to the TB

Those are all the things that come to mine now. Hope it helps.

I have added in bold above.^^^

For the obviouse, make sure your radiator is topped off and that you have burped out all trapped air that could be in they system.

Keep in mind that another possibility is that your temp sensor could be faulty, the best way to check this out is to get a scanner and see what the computer is saying the temp is.

If all else fails go to an autoparts store like AutoZone and get a coolant pressure tester(loaner tool). With your engine cool, take off the radiator cap, put the tester on the radiator and pump the tester up to about 16-17 psi. Observe the gauge, it will hold pressure if there are no leaks. If it doesn't not hold pressure, check around and see if you can see any coolant leaking (check under the car to see it dripping, even look inside the passenger compartment, that will check to see if your heater core is leaking). Fix or repair what you find to be leaking. Sometimes it depends on how much coolant has leaked, but with leaked coolant all over the engine it may be hard to locate where the leak is, if this is true for your engine, make sure to clean the areas where here is coolant present and retest.

Good luck with finding out what is making your engine overheat, if none of this works for you, it could be something more serious, like possibly a head gasket (worst case scenario).

Either way let us know what the deal was.

**bigpapa53023** · 10-20-2008

Thanks guys for all the help. I think i have the problem fixed and it was a lot more simple than i had thought. I noticed that i was not gettinh a whole lot of heat out of my vents so i cracked the bleeder right above the water pump and i got a whole lot of air to come out and as soon as i did that my temp went down. Seems to be running better now but not perfect. I just have to bleed it every now and then but it is getteng better. Thanks again for all the help.

**SyntheticShield** · 10-20-2008

Theres a bleeder valve on the water pump?

**Blown97** · 10-21-2008

Originally Posted by SyntheticShield

Theres a bleeder valve on the water pump?

No, on the 3.1L there is a metal pipe that has coolant running through it and it has a bleeder on it much like our water outlets do.

**bigpapa53023** · 10-21-2008

Originally Posted by Blown97

No, on the 3.1L there is a metal pipe that has coolant running through it and it has a bleeder on it much like our water outlets do.

Yeah sorry it is not on the water pump but right above where the pump mounts where the heater lines run. Thats where the air will get trapped and it wont let it push enough coolant volume to keep the engine cool

**2KWhiteSE** · 09-21-2009

I've had relatively the same problem with mine too. I had replaced everything that I could think it could be. first was the gaskets, noticed there was definately a leak. still overheated after that. So I replaced the water pump and the radiator and the t-stat and the sending unit all afterwards over a period of time. still couldnt figure out what was making it overheat. I found out that my fans werent kicking on when they needed to. so since I knew they worked, I replaced the relays. It stays at a more normal temp now. But if I get into the pedal a little, it goes back up like it use to. Oh and by the way both hoses still stay hot once it warms up. My heater core works fine, blows nice warm air all the time when I kick it on. would the t stat be faulty with this being the case? or should I check for more air being a problem again?

**2KWhiteSE** · 09-30-2009

I have 2 questions, if you take out the thermostat, will it run cold most of the time? and how do u go about fixin the fans, if they dont kick on when you turn on the AC? but will kick on at later intervals than what they are normally suppose to?

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