No leaks or burned coolant, the coolant is full to the radiator neck. But all of the sudden last night when I was at work delivering in the city, it started ******* out and I noticed the temp gauge was all the way to H so I turned it off for a while with the heat on and then turned it back on with the heat on when it got down to 2/3 of the way to the H and it was fine after I had the heat blasting the rest of the night. I checked the reservoir and it was just about empty, so I put some coolant in and ran it for about 10 minutes to try to bleed air out but it was fine. Then tonight it tried overheating again, got 2/3 to the H and I turned the heat on and it was fine. I don't remember the fan turning on last night, but I might have just not noticed it running if it's a normal noise. But I drove without the radio on, but the heat on tonight and the temperature was at the normal point all night but I didn't hear the fan and I popped the hood a couple times to see if it was turning but it wasn't. So I'm going to assume that the thermostat is fine and that the fan just isn't working. Is there a relay or just a motor I need to try to diagnose? How do I go about diagnosing this? Thanks.

 

Fan,thermostat,plugged radiator,

if it went to h and the started bogging that could of been the result of the head gasket blowing and water leaking into the combustion chamber causing it not to combust.


take it to your local smog station and ask them to use the exhaust probe and sniff the radiator with the cap off once its a normal operating temp.
good luck

 

It wasn't acting weird I just noticed it was getting a little bit slugging driving up a hill. I would think if the gasket is blown it would be eating coolant but it is fine in that regard.

 

it doesnt take that much coolant to make a engine combust improperly. but i could be wrong.

turn on car with radiator cap on after being bled for air.. is lower rad hose cooler than upper? i mean alot cooler to the touch? if so then thermostat is faulty


are the fans turning on when the vehicle gets to normal temp?

with the radiator cap off does the car over heat? if so either you have water only and its boiling creating steam or you have pressure from the combustion chamber entering the cooling system.

is the coolant/water rusty? if so you might have a clogged radiator.

 

The coolant looks perfectly fine, it was bright green with no **** in it. I let the engine run for five minutes after I got home tonight and no fan. I know the fan still works because we accidentally jumped it recently trying to jump start the AC clutch. So I'm thinking either bad fan relay/switch or pocket of air in the system?

 

I would check the Fan. make sure they work and blowing the right direction