Year: 2002
Engine: 3400
Problem: Recently replaced the thermostat on my car because it was overheating. The thermostat was put in correctly and all is back together. When I drive the car, it blows out hot air while idling in the driveway and for the first 10 minutes or so after I start driving. After 10 minutes, usually up to normal driving temperature on the temp gauge, the engine temp gauge will fluctuate between hot and cold. It will be cold as the temp rises on the gauge and heat up when the temperature goes down the temp gauge. This cycle takes less than 2 minutes. At idle, the temp increases steadily, but once I take off, it goes down again.

Steps take:
1. I have bled the system approximately 4 times.
2. Verified the coolant fans come on by running the A/C at full blast.
3. Checked the serpentine belt to ensure it is not bad. Not sure if the water pump is bad or not

Any help provided would be greatly appreciated.

 

Sounds to me like either you got a junk thermostat thats stuck open...Or there air trapped in the cooling system...Id try to bleed off the air pocket first...It may take more than 1 try to get all the air out of the system....
Possibly 3 or 4...times...

 

Open bleeder above water pump while filling radiator, close it when done filling. Fill overflow jug. Run engine for a few minutes with radiator cap on. Once warm open up bleeder on t-stat housing until a solid stream of coolant comes out. Close it. Burp engine from idle to 3k for a minute or so in short burps. Let sit and cool down. It should suck coolant in from the jug if need be. Repeat all of the above as needed.


DO NOT open the water pump bleeder while running. All you will do is introduce air into the system and fight yourself.

 

Thanks, a couple of questions

I hope it is not the t-stat that bottom bolt it a PITA to get to.

The bleeder valve that I have been opening is on the housing going to the t-stat is that not the correct one? Revving the engine to 3k should not be done for a whole minute, right? Just 10 seconds bursts maybe?

 

Yeah, open one on t-stat hosuing while running. Just quick 1-2 second burps to 3k. Maybe do that 10 times in a minute.

 

so did you get your issue fixed?

 

I thought I had the issue fixed. The other day, it was 55 degrees when I drove the car and it had no problem with heat. Drove the car for approximately 50 miles. This morning, it was 32 degrees when I left the house and within 10 minutes, the temperature was moving up the gauge again. It was fluctuating between hot and cold air, then just cold air. It eventually started blowing out just cold air. It eventually threw the high coolant alarm.

1. I have ran the car about three times trying to get the air out of it.
2. There is no coolant on the ground.
3. There is no coolant in the floorboard of the car.
4. The radiator fans come on when the AC is turned on, so it's not the fuses for the fans anyway. Not sure if the fans are coming on when the high coolant alarms are coming on.
5. If I pull over to the side of the road and let the car sit for 2 minutes, I can drive it for about 10 minutes again before it starts to start getting house again. It takes about 15 minutes to throw the high coolant alarm again.

 

Do you have to keep adding coolant?

Maybe it needs upper and lower intake gaskets?

 

Shortly, after posting this message, I took it to an incline and filled it half way with antifreeze, which I would expect after draining it to replace the t-stat. I have not had to add much since. When I open up the bleeder valve, coolant comes right out, but I close it quickly. It does not seem to be a coolant level issue, but I am no expert.

 

If you keep having to add coolant, you are loosing it somewhere. Check your oil cap, look inside the valve cover and check the oil dipstick? Does the oil in any of those spots look "sludgy" or "milky"? If so, that is a possible sign of bad LIM gaskets.
You can also get a radiator pressurer tester as a loan-a-tool from a local auto parts store. Use that on the car when it's cold, get it to about 13lbs of pressure and you can SAFELY inspect for leaks while the car is off. You may hear a hissing or see bubbling around the LIM gasket if that's the issue.

Next question, are you noticing any large white clouds of smoke when you first start the car? If so, this might be a sign of a bad head gasket.