I have a 2000 Grand Cherokee Laredo 4.0 it over heated n blew head gasket. The following have been replaced and it still runs hot (210-220+) I shut it off at 220 otherwise I'm not sure if it eould keep climbing in temp. But this was all replaced new head gasket, head machined, radiator, water pump, coolant temp sensor, thermostat, fan is hard wired to stay on while running, also had whole new exhaust put on so the cat isn't plugged. It runs with less power then it should my other 4.0 jeep has wayyy more ***** and stays at a steady 180 temp. If you have any ideas lemme know!

 

What are you using for the temperature reading? The gauge on the dash? If so, are you sure that's correct? I would try to verify that with a scan tool with data stream ability, but I know most people don't have access to that. Above 180 degrees, is the air coming off of the radiator hot? Does the heater inside work? Some of this might be redundant to you, but I figure I'd ask...also, stupid question, is the fan wired to run the correct direction?

I agree you got an issue, if the fan's hard wired, it shouldn't get much hotter than the t-stat open temp. If you've got hot air blowing off the radiator and heat inside, it sounds like its circulating good. How long does it take the system to build pressure? As I understand it, your model year has a bad habit of cracking cylinder heads, was that checked when you had it machined? If you immediately have pressure on the cooling system after a cold start, you have a compression leak. If it's bad, you could leave the rad cap off, start the engine, and it'll immediately spit coolant out of the radiator, maybe with some distance, too.

Cool air over radiator above 195 degrees, with good heat inside would indicate a faulty thermostat. Add no heat inside to that situation, you may be looking at a water pump with the wrong rotation. If you have instant pressure in cooling system, or nearly instant, that could indicate a combustion leak, or an air pocket inside the system, both of which can also keep the coolant from flowing.

 

I'm using dash gauge for reading. I plan on getting it scanned for actual temp Friday to make sure that's working.heat works inside. I'll check fan direction & heat off radiator. It takes like 4miles of driving to get it yo temp of 210. The head was machined n seal tested and it doesn't leak anything. I'll try the starting it w.o cap n see if it spits it out.Also if I run it at 55mph it stays at 210 but if I drop down it starts getting hotter. I'll check all that though! Thanks

 

You "might" not have an issue then. Get the temp checked, as you said, but as Dave said in the other thread you replied to, you probably need not be concerned until you see temperatures around 230-240. Especially if it's pretty hot where you are at.

 

It's not hot here in MI lol I'm gonna go run it all over trails tonight to see how hot it'll get just putting around. I'll shut it off at 240 though. And I'll get the rest checked out Friday to see if any of it could be affecting it. Thanks allot for advice!!! I hope its something dumb and runs cooler then what it is!

 

My fan was backwards... wow that was allot of time & money on such a dumb thing. Thanks again for your help!

 

Not a problem, Jess. That's what we're here for, to spread our knowledge and experience to help others. Thanks for posting your results. It may help someone else.

BTW, my WJ 4.0 NEVER gets above normal, even sitting idling for extended periods, or city driving with stop-and-go at 90* OAT. It must be I got one of the good ones!

 

Awesome, glad it was a simple fix.