Running A Little Hot :(

Hello All,

My very stock 1974 CJ5 232 I6 has been running a little hot...

I decided to replace the water pump and thermostat and go from there.

So, I now have a brand new water pump, thermostat housing and thermostat.

The radiator is new as well.

The Jeep sounds as good as she did brand new. Tuning sounds perfect with smooth acceleration and just a beautiful quiet little 232.

It heated up to temperature fine and the thermostat opened and let me add more fluid just like is should have...

I took the Jeep for a test drive this evening in relatively cool weather for Florida 79 degrees and all seemed fine until I stopped at a traffic light.

Any brief pause at a light or idle causes the temperature to quickly rise to just above 3/4 towards H.

When I take off again I can feel the engine complaining a little about the heat, just ever so slightly rougher running, then the temp drops back down but never gets as cool as she used to run.

Any ideas? Could this be an oil pump issue? That is about the only part I think I haven't checked or replaced.

Thank you for any advice

 

Good Dog! Nice Jeep.
I don’t know much but is the fan working correctly? Did these come with a fan clutch?

 

A thought, based on your details... the fan has very little effect when cruising, but does help when at slow speed or stationary. Check out the fan clutch and/or fanbelt tension.

Also - are you sure the temp gauge you are relying on is accurate?

 

Clogged radiator, lower hose collapsing, running lean ( idling you are not using the mains so checking with a vacuum gauge), timing off, verify gauge is actually correct using ir gun. Lots of little things to weed out.

 

All that.

 

If you don’t have one a good fan shroud will make a huge difference at low speeds/stopped.

 

Checked oil pressure at hot idle with a good direct read pressure gauge?
If the engine oil pressure were very low at idle it might cause a little heat increase. just a thought. Did you say it has a new radiator? Original jeep radiator? or aftermarket? I have wondered about the after market radiators, if they have the capacity for heat transfer that the original jeep ones have..

 

Thank you! I believe the fan is working correctly with no clutch. Seems to be turning just like it always did, but the overheating is a new issue and I drive the Jeep daily and often.

 

Thanks Pete! I'll check out the temp with my thermal temp gauge...not sure how reliable those are but I have one for A/C diagnosis for our home. Not sure if it has a clutch? But the fan seems to be operating like it always has just spinning at engine speed and the belt seems to be tight enough not to be slipping. Thank you for your response

 

Thank you Rich That is a good list to check, will do so as much as I can... Is there a good tutorial on checking the fuel/air mixture with a vacuum gauge? I've never heard of that, but I do have a new vacuum gauge I can use. Also the timing? I ordered a simply timing gun from Amazon last night for $26. Hope that might be enough to verify timing... Assuming TDC is correct, do you know the correct timing for a stock I6 232? Thanks so much for your help

 

Thank you! I was looking around of a shroud last night, but was not able to locate one online for a stock I6 232... If you know of a source I would be happy to order one for sure. Much appreciation

 

Thank you! Yes, I installedbrand new radiator when I purchased the Jeep a few years ago and it's been running great ever since... The radiator was from AutoZone and looks like the original. The Jeep actually ran very cool up until recently. I'll check the temp with an IR to verify today and I think purchasing a good direct read oil pressure gauge is the way to go. Looking into that now. Thanks again

 

This is very likely your issue. If you can’t find a Stock(ish) shroud Summit Racing has several built it yourself options/kits.

I switched to an 2 speed electric Fan with a shroud that covers my radiator completely. Take your time when searching Summit and call them for ideas. . They have lots of options.

 

Too nice to be driving on the beach. Salt, sand and rust. Lug nuts have a nice orange color. That said, I would suspect an ignition problem is causing the overheating issue.

 

Doesn't cost anything to try advancing the timing a little, it might solve the problem, but if not you can at least rule that out.

 

If you do this first take a sharpie or better a paint stick and mark where it is now.

 

Could be headgasket. Check your antifreeze for hydrocarbons.

 

X2, I did not think of that, I have had head gaskets and cracks that caused overheating, If I may add, it usually would be worse the harder you worked the engine rather than at idle. Either way it can cause the issue though.