cooling system woes.

[gertsch]

So I had to put in a new cooling system in my Grand Cherokee last march. I put in a new aluminum radiator in new water pump, thermostat, and hoses. So here is my dilemma, after all this work towards the end of may the engine started running hotter and hotter, especially with these wonder full 100 degree temp as of late. If the jeep is sitting and idling it runs well below 210 and soon as I start driving the temp starts climbing. With or without the a/c on. It still climbs up to just before the red on the gauge. I'm running a Taurus 2 speed fan and it is working on both speeds. Before if I can the fan on high I could literally watch the temp drop a few degrees. Now it cant even hold back the temp when driving. I did a compression check on the motor and all cylinders are at 120psi. No white smoke out the exhaust, oil is its normal color. The only thing I haven't done is pressure test the cooling system. Am I wrong to think my head is cracked or maybe its my Chinese aluminum radiator is plugged up? Any help or suggestions are greatly appreciated. Also its a 4.0l straight six engine.

 

[ChestonScout]

New cap?

 

[Spork]

I'd be looking at the thermostat, does it go to a point then stay there for a while before starting to climb again or is it just a consistent rise?

 

[gertsch]

New cap and thermostat last week. I can watch te temp rise then the thermostat opens an the temp drops then climbs back up and keeps going.

 

[TurboMinivan]

I did a compression check on the motor and all cylinders are at 120psi. No white smoke out the exhaust, oil is its normal color. The only thing I haven't done is pressure test the cooling system. Am I wrong to think my head is cracked or maybe its my Chinese aluminum radiator is plugged up?

Your compression check looks good, though you could still have somebody test to see if there are any hydrocarbons in the coolant.

As for the radiator, any radiator shop could easily test it for flow. It seems you are getting at least some circulation through the system since it doesn't overheat while sitting still. A restriction in the radiator might be a contributor to your situation. (EDIT: if you had one of those nifty laser thermometers, you could point it at individual tubes of the radiator core on the outlet side and see if all rows are doing their job.)

Another thought: can sufficient airflow reach the radiator itself? How does your A/C condenser look? Is it plugged up with bugs, bent fins, etc? Is there any debris accumulation between the condenser and the radiator? Just a thought.

 

[gertsch]

Your compression check looks good, though you could still have somebody test to see if there are any hydrocarbons in the coolant.

As for the radiator, any radiator shop could easily test it for flow. It seems you are getting at least some circulation through the system since it doesn't overheat while sitting still. A restriction in the radiator might be a contributor to your situation. (EDIT: if you had one of those nifty laser thermometers, you could point it at individual tubes of the radiator core on the outlet side and see if all rows are doing their job.)

Another thought: can sufficient airflow reach the radiator itself? How does your A/C condenser look? Is it plugged up with bugs, bent fins, etc? Is there any debris accumulation between the condenser and the radiator? Just a thought.

The coolant system test for hydrocarbons is a great idea! I do have a laser thermometer had had the same thought cross my mind as well. There many things I'm going to try next especially having outside opinions help guide my frustrated mind. I will test and report back.

 

[gertsch]

Well I got bored at work and decided to use our gas analyzer and see if it would pick up hc's in my cooling system. Needless to say I have hc's from 20 to 75 floating around in there. So going after the head gasket.

 

[Houndoc]

Caught my attention with GC cooling system problems. My dad spent 3 days last week sitting in Yellowstone while he got overhauled. Radiator cracked, got that replace and was still overheating (was not having any problems before the radiator went out). Thermostat was bad, replaced. Still running hot. Turned out water pump went out as well.

Took a lot of the fun out of their vaccation.

 

[gertsch]

As soon as I finish the long arm install on my friends cherokee I will begin the tear down of it.