E4_Mafia

Hey so I have an xj with 174k miles on it. It runs perfectly I've had it for a month. I found out about the notorious 0331 heads (which I have) anyway do I need to be worried I don't know if they are aftermarket heads I did see a stamp NHV on the side of the heads but I don't know what the previous owner did.
So considering my high mileage what can I do to prolong the life of my heads and how worried should I be

abodyjoe

i have a 2000 with over 200k on the original head.. make sure your cooling system is good and then just keep an eye on it.. they don't all crack.

there are upgraded heads out there.. one from chrysler the "tupy" head. then there is the aftermarket ones from edlebrock and clear water cyl heads

E4_Mafia

Okay I'll do that I just flushed the coolant I didn't see anything weird

extrashaky

No. You just need to be aware of the problem and symptoms so that if you see them you know what to do. The biggest early symptom is the coolant level in the overflow bottle dropping without any sign of a leak. Sending off an oil sample for analysis at a lab like Blackstone at every oil change will detect coolant in your oil even before you can see the coolant level dropping. The heads can crack without overheating first, but you can reduce the likelihood yours will crack by keeping your coolant system maintained and refreshed periodically.

As long as you catch it early, you can swap the head before it does any bearing damage. If you start feeling paranoid about it and want to swap it preemptively so you can have full confidence in it, you can replace it with a Clearwater head on a Saturday afternoon for around $500. The head shows up ready to bolt on.

It's easy enough to find out. When they crack, they typically crack between the #3 and #4 cylinder right under the oil filler hole, and you can sometimes see the crack by pulling the oil filler cap in the valve cover and looking right down inside there with a flashlight at the top surface of the head. Since that's where people look for a crack, all the replacement 0331 heads have marks cast into them right there. The Tupy 0331 has the word "TUPY" cast into it. The Clearwater head has a number there. So if you look into that hole and just see a fairly smooth metal surface, it's most likely an original casting 0331. Anything else there will indicate an aftermarket 0331.

Turbo X_J

OP, don't worry about all this jazz that might happen.^ You may get struck by lightning but that's no reason to spend your life in the basement.

Carry a spare MOPAR CPS in the vehicle because that will fail, more than likely at the worst possible time.

extrashaky

You quoted a post where I told him not to worry, then responded as if I told him to worry. Why exactly would you do that?

E4_Mafia

I appreciate it guys I just got out of the army 6 months ago I honestly bought a jeep because they are reliable and mean looking. I don't think I could replace the heads. I just did the thermostat and coolant it looked good to me. Honestly if they break I'll have to find someone near me ( Portland) to help me. I honestly think it would have broken already. The rig has 174k miles.

'00 XJ

No expert here, but you're right to keep the fluids fresh and the cooling system healthy. At 174, 000 there should be plenty of good miles ahead.

Thank you for your service.

Firestorm500

Are you sure you have a 4.0 Cherokee? You keep on saying "heads" like you have a V-style engine.

The 4.0 only has one head.

Kap

For what it's worth, I replaced the rad at 173,000 mi -- no problems since. Everything is fine ... Mine gets tough use, then sits for months, then gets tough use again in 4lo offroad and 2hi on the Interstate. No special maintenance other than oil change and eye on fluid levels... but.... Fingers crossed, gripping rabbit's foot , touch wood, and so on.

E4_Mafia

Yeah hahah it's a Cherokee I know I'm used to having a v6 Suv not a straight. I will do what I can to keep the temp down but it is what it is. Buddy of mine has a 2001 with 297k miles original 0331 head. So I'll just be cautious but I'm not going to let it ruin my day