I have not been able to figure out what is wrong with my Jeep, it's been 2.5 days and least 20 trips to the parts store and just have no clue.

So I will start at the top. Last Thursday I was driving home and my Jeep jumped up to 260º, and blew out a bunch of coolant, I limped it the last 2 miles home after letting it cool. I don't think it went all the way to 260 because after 220, it jumped straight to 260, I don't think it instantaneously jumped 40º. My first thought was a bad thermostat, so I replaced it. Still did it. So I decided to take it to a buddies house to have him help me figure it out. But then it wouldn't run unless I started it and got the RPMs to around 2-3K, if it got below 1000 it stalled.

So I borrow a tow dolly and my buddy towed it with his Jeep to his place. It was then decided there was a bad water pump. After replacing that, no change at all, except the water pump was new. still couldn't start it without racing the engine. The next day, we started it and it ran but idled terribly. I was also going through a lot of coolant, but couldn't tell if it was just thirst from throwing out a bunch of coolant or if the head was cracked. There is no coolant in the oil, I've been checking it a lot, but still wonder if the head is indeed cracked.

Tonight I was trying to move it around a little and the hose that goes from the top of the radiator to the thermostat blow clear off, and it was on there tight. I also took the thermostat clear out to just let it run free and see what happened. We checked it and it was too hot to touch, but the lower radiator hose was cool. So now we think that there is a blockage in the radiator that is stopping the flow of coolant/water. But it still doesn't explain why it idles terribly. Shortly after we noticed that there was a little bit of smoke coming from the side of the valve cover by the injectors somewhere between cylinder 3-5. Now that makes me think the head may have cracked. I am getting fuel no problem, and to the best of my knowledge, I am getting spark too, so I don't think that either one is causing the starting/idle issues.

I am unable to really figure out what the hell is wrong. I just wondered if the brain trust here might have an idea or at least tell me I am heading in the right or wrong direction. Thanks for the help in advance.

 

The gauges in that year lie.
They're driven by the PCM, Chrysler 'adjusted' them to read an extreme value when the motor starts to run too hot so the driver will notice. Instead of reading actual temp, the PCM drives them all the way to the right. it probably wasn't really 260 deg.

If you have hoses blowing off, you likely have cylinder compression entering the cooling system. Head gasket, head, etc. If you run it with the cap off do you get gurgling?
Do you have access to a cylinder compression tester? Cooling system pressure tester?

 

I don't have access to an testers at the moment. I will check next time I am near my Jeep but I think I do remember some gurgling with the cap off. I knew it wasn't getting to 260 either because of how it jumped. Plus if I turn it off and immediacy turn it back on it will read just above 220. It seems as if the valve cover gasket is worn. But I don't know how that gasket would put compression into the cooling system unless beneath that there is a bad head gasket. I will probably be taking the head off here soon. Possibly Thursday to see what is going on down there.

 

Unfortunately, with an 00-01, an engine overheat almost guarantees you of a cracked 0331 cylinder head.

First thing I always do is to remove the oil filler cap and with a hot engine and a good light, peek in there and see if you can see coolant seeping through. Sometimes (not always), you can see the crack as it always cracks between cylinders 3-4, which is right there.

A compression test is good at snaking out a blown head gasket, which is also a possibility, but the compression test is not a good one for diagnosing a cracked 0331 head. A cylinder leakdown test is much better, but as you likely have either a cracked head or a blown gasket, you may as well just pull the head.

And I'll make this recommendation. If you have a factory 0331 head on there now and you take it off, it should never go back on. The head is a dog and because of the potential for cracking, resolve it now. Clearwater Cylinder Head and Alabama Cylinder Head can set you up with a beefy replacement head for around $500.

Good luck and keep us posted!

 

Well another day went by and we can't figure it out still. The electric fan is not working but I don't think that should cause overheating this easily. And doesn't explain the real rough idle at operating temps.

So I decided to pull the head. I know a shop that can tell me if it's cracked, depending on what the charge to magnaflux it, I'll either have it tested or just drop a head, either a TUPY or an 0630 depending on what they want to charge to test it. If it comes up cracked I'll be taking a look at any damage that has been done to the rest of the motor. Hopefully the motor is fine

Also I tools the valve cover off and I couldn't find any cracks or coolant. But I knowing isn't always visible. I lose a lot of coolant, but since during different tests I blow coolant everywhere I don't know of the radiator is just thirsty or if this coolant is finding other places to go. Tomorrow I should be able to finish taking the head off, and try and get it over to the shop before they close so it can possibly get tested. Unfortunately with my budget the junkyard is most likely where the head is gonna come out of, but since I won't be grabbing another 0331 (except for a TUPY if I find one) I think it'll be fine.

 

It was cracked we got it off. I drained the oil and it was black so I don't think I trashed anything inside the motor. So I think I'm gonna try and get a new cylinder head put on here soon and get it back on the road. hopefully this will take care of the crappy idle and all will be good.

 

I've been reading that I can drop the oil pan and check bearing clearances or something like that to see if there was any damage done to the motor. Does anyone know how to do that. The motor oil was not milky, so only a little bit got in, And it wasn't driven much at all after everything started going wrong, but I want to be sure before I spend $425 on a new J&C Enterprises head.

 

Just my opinion, if the cooling system was neglected to the point that the radiator is plugged solid, you should yank the motor and have the block boiled out anyway. This will also give plenty or opportunity to check bearings and what not. Probably not a bad idea to change out the heater core as well. Sorry, but I would just do it all at once and get it over with.

 

Hmmm. Never heard of block boiling. What is that? And the radiator want plugged. We checked it and it was fine.