Overheating Sob Story

[Foothill]

Souske - why is ZJ clutch better?
Frank - could be both the shroud and clutch contributing. Hope you put in new clutch and report back the results. Good luck

 

[souske]

It pulls more air than the xj one

 

[FrankHKP7]

Re: Overheating Sob Story - UPDATE

Thanks for everyone's advice.

I replaced the shroud and took it for a ride Thursday.. overheated.

This morning I put the new fan clutch in...

Result: Still overheating!

What should I try next?

Frank

 

[Bjorn86]

Is it doing this at higher speeds? Do you still have the spring in your lower radiator hose? It could be pinching shut while driving, and may explain why it can idle for an hour and not overheat, but overheats while under a load. Just a thought.

 

[FrankHKP7]

Is it doing this at higher speeds? Do you still have the spring in your lower radiator hose? It could be pinching shut while driving, and may explain why it can idle for an hour and not overheat, but overheats while under a load. Just a thought.

No, it's a replacement hose. No spring.

I'm getting ready to unload this thing for parts...

 

[chasdb]

Don't throw in the towell.


Generally you should have a 10-15 degree drop in temp thru the radiator from inlet to outlet. I haven't checked Cherokees but it may have to be hot enough for the fan clutch to lock and e-fan to kick on to see delta t.

Have someone hold the rps at high idle and watch to see if the lower hose collapses, I have seen this problem.

I don't know if a combustion leak in the 4.0 would show as high temp or would just show as low coolant level as have seen it on other engines as combustion gasses displace coolant. I would try a pressure test on the radiator up to 18 psi, engine off and see it the pressure holds steady. If it holds check for a combustion leak. Install the tester on the filler neck but do not pump up. Start the engine and if pressure quickly builds you have a combustion leak, don't let the pressure exceed 18 psi to prevent damage. If there is no immediate pressure increase- pump up to 12 psi and watch the needle. If it bounces/ vibrates there is a combustion leak. You can isolate leak by shorting each spark plug untill the gauge stops / decreases vibration.

Best of luck- Charles

 

[FrankHKP7]

Hey guys, FINALLY figured it out. The solution was another flush and running a bottle of the peak cooling system cleaner. Apparently, there was a ton of extra crap sitting in the rad and the water jacket. Truck runs at a perfect 210 - 215!

I'd like to thank everyone for their help! I appreciate all the advice and direction!

Thanks again!

Frank

 

[old_man]

Everybody needs to remember that if you don't burp ALL the air out of the system, you can get artificially high temps. Point it down hill, loosen the temp sender until antifreeze comes out, then tighten it back down.