Possible to get an '01 without a weak head?
CF Veteran
Joined: Jul 2012
Posts: 3,686
Likes: 6
From: Hudson, FL
Year: 1999
Model: Cherokee
Engine: 4.0L Inline 6
Short answer: No.
Long answer: It depends.
All '00 and '01 XJs had the 0331 head, which had a casting flaw that causes some--not all--of them to crack for no reason. It did NOT come in the '99 XJ. That confusion comes from the fact that it was installed in the '99 WJs, and that some of the early '00 model year XJs had 1999 build dates on the door (which makes sense if you think about it). XJs with model year 2000 and 2001 are the ones at issue.
The 0331 heads usually don't crack before 100K miles and usually crack before 200K if they're going to do it, but people have reported cracks at lower and higher mileage, so you can't count on it. Somebody here posted that he had 400K miles on his original head. The problem with the 0331 is that you simply don't know if yours is going to crack until it does. So you have a couple of options:
1. You can leave the original 0331 on there and watch like a hawk for signs of a crack, then swap it for an aftermarket 0331 with the casting flaw corrected if the crack develops. That requires you to know the signs. The most obvious one is unexplained coolant loss from the overflow bottle without an obvious leak. You may also see odd temperature spikes, evidence of exhaust gas in the coolant, brown sludge forming in the coolant, and in some cases you can look right down in the oil filler cap and see the crack weeping coolant. If you're going to watch and wait, it's better to catch it early to avoid as much bearing damage as possible. To that end, it's a good idea to have a $28 oil analysis done at each oil change as an early detector of coolant getting into the oil.
2. You can preemptively swap the head for a Clearwater 0331, a TUPY 0331 or an earlier 0630 head to avoid the issue altogether. The easiest is the Clearwater 0331, which costs around $500 and comes almost complete and ready to bolt in over a weekend. There are plenty of DIYs around that show the process, which isn't complicated.
The advantage to #1 is that you don't throw money at a problem you don't actually have. The disadvantage is that by waiting and gambling on the head, you risk having it crack when it's most inconvenient. The advantage to #2 is that you can take away the doubt on your own timetable and have confidence in the motor without always worrying about whether it's gonna go.
What you choose really depends on your situation. If an XJ with the 0331 was my only transportation, or if I routinely drove it very long distances, I would set aside the funds and make time for#2 so that I could feel comfortable relying on it. If I had alternate transportation, I would probably just keep driving it with the original head on it and monitor for a crack, knowing that I would have something else to drive if it cracked when I was out of money or had no time. That's just me, though, so you may think differently.
While the earlier 0630 and 7120 heads can crack, it's unusual. When it does happen, it's usually because somebody overheated it. With the original casting 0331, you didn't have to overheat it to crack it. They just crack if they feel like it. The crack as a frequent issue is really restricted to the original casting 0331.
Long answer: It depends.
All '00 and '01 XJs had the 0331 head, which had a casting flaw that causes some--not all--of them to crack for no reason. It did NOT come in the '99 XJ. That confusion comes from the fact that it was installed in the '99 WJs, and that some of the early '00 model year XJs had 1999 build dates on the door (which makes sense if you think about it). XJs with model year 2000 and 2001 are the ones at issue.
The 0331 heads usually don't crack before 100K miles and usually crack before 200K if they're going to do it, but people have reported cracks at lower and higher mileage, so you can't count on it. Somebody here posted that he had 400K miles on his original head. The problem with the 0331 is that you simply don't know if yours is going to crack until it does. So you have a couple of options:
1. You can leave the original 0331 on there and watch like a hawk for signs of a crack, then swap it for an aftermarket 0331 with the casting flaw corrected if the crack develops. That requires you to know the signs. The most obvious one is unexplained coolant loss from the overflow bottle without an obvious leak. You may also see odd temperature spikes, evidence of exhaust gas in the coolant, brown sludge forming in the coolant, and in some cases you can look right down in the oil filler cap and see the crack weeping coolant. If you're going to watch and wait, it's better to catch it early to avoid as much bearing damage as possible. To that end, it's a good idea to have a $28 oil analysis done at each oil change as an early detector of coolant getting into the oil.
2. You can preemptively swap the head for a Clearwater 0331, a TUPY 0331 or an earlier 0630 head to avoid the issue altogether. The easiest is the Clearwater 0331, which costs around $500 and comes almost complete and ready to bolt in over a weekend. There are plenty of DIYs around that show the process, which isn't complicated.
The advantage to #1 is that you don't throw money at a problem you don't actually have. The disadvantage is that by waiting and gambling on the head, you risk having it crack when it's most inconvenient. The advantage to #2 is that you can take away the doubt on your own timetable and have confidence in the motor without always worrying about whether it's gonna go.
What you choose really depends on your situation. If an XJ with the 0331 was my only transportation, or if I routinely drove it very long distances, I would set aside the funds and make time for#2 so that I could feel comfortable relying on it. If I had alternate transportation, I would probably just keep driving it with the original head on it and monitor for a crack, knowing that I would have something else to drive if it cracked when I was out of money or had no time. That's just me, though, so you may think differently.
While the earlier 0630 and 7120 heads can crack, it's unusual. When it does happen, it's usually because somebody overheated it. With the original casting 0331, you didn't have to overheat it to crack it. They just crack if they feel like it. The crack as a frequent issue is really restricted to the original casting 0331.
CF Veteran
Joined: Jun 2011
Posts: 8,014
Likes: 17
From: Louisville,KY
Model: Cherokee
yup, see, now I am thinking I should get the '01 and just replace the head. It depends on what the coolant looks like, if its brown, I may still pass on it, because it could be that there is bearing problems already, due to it running four years on a cracked head. But if its clean... I may get it. Like what abodyjoe and EvstaG said, this may not be such a big problem, and even if it is, I can just swap out the head and then not worry about it. That is only if I know the engine is not already damaged.
Problem is... seller is asking 8500 due to a lot of aftermarket suspension mods. I like the mods, but cant justify 8500. I could maybe justify 5500. I doubt he'll go that low considering his starting point.
Problem is... seller is asking 8500 due to a lot of aftermarket suspension mods. I like the mods, but cant justify 8500. I could maybe justify 5500. I doubt he'll go that low considering his starting point.