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Head Cracked! rebuild

T

TBCherokee

NAXJA Forum User
Location
cincinnati, OH
I have a 2001 xj 68,000 miles, lost coolant alot, ran good, great oil pressure, cooled engine well, but had slow steady loss of coolant, found out head is cracked after a shop did a pressure test.
I'm having a shop replace the head,
i want to keep the xj.
I don't know much of what it involves? I know it will fix the coolant leak, and
the original problem.
But , what should i exspect after the work is done?
Will it run better too? , or worse? or same?
will i get more life out of the engine? etc. how will i know if they do a good job? any hints?
Can anyone comment about replacing the head or anyone else had to do
it on a 2001?
BTW. my jeep has never overheated, and i have read all the threads with the info on the #0331 cast head cracking between #3 and #4 cylindar.
thats where mine cracked.
 
Replacing the head on an XJ is fairly simple - you could do it yourself if you have a good afternoon to work in, a covered, well-lighted area (you don't want to be interrupted by the weather,) and some hired muscle for lifting the old head out and putting the new one in.

While the alloy used to cast the blocks changed a little when ChryCo took over, the basic design didn't, and logevity should NOT be an issue. While I'd not think you could expect a half-million miles out of the thing, I have been wrong before...

If they let you keep the old head, I'd like to talk to you about getting it out here. See my thread in "Wanted" (I think that's where I put it...) for the whys and wherefores, but the long and short of it is that I'm trying to collect a set of heads to run through a bandsaw for analysis and experiments, and I don't care if they're cracked, warped, or whatever (in fact, I'd prefer it. That way, I don't feel bad about slicing the thing up...)

5-90
 
If you can try to get them to order a pre2000 head. I can't rember the cast# off the top of my head, but the info is here (on NAXJA) I think it is in a thread started by Dr. Dyno. It will be a direct bolt on and flows a bit better than the 0331's. Not to mention it doesn't have the cracking issue.
 
My issue is what to expect with the new head?
i read all the threads on cracking, and mine was cracked,
but what about after it is repaired?
any problems with a new head on and engine with 60,000 miles on it?
like lower end problems or burning oil , oil suckin up past old rings? etc.

anyone had problems with there engines after a head change?
 
try the 0630 casting i believe it was used in 97-99's might be used more years though. 0630 seems to be as bomb proof as the earlier casted heads. also 0630 will also fit accessories except for the coil pack rail. you might be able to come up with a fabricated mount to hold the coils. mike
 
x99j said:
try the 0630 casting i believe it was used in 97-99's
Click to expand...

That is correct.

If I were you, since you've been losing coolant, you're obviously burning it. I have to wonder what kind of damage has been done internally to the engine. I know you said you had good oil pressure, but if you can remember, what were the readings hot, cold, idle, driving, etc. If it's pretty good still it might not be too late. I'd definately start by changing the oil, DON'T run it the normal 3K before changing it, change it sooner, perhaps around 1000-1500 miles. Doing this a couple times would probably get out any remaining coolant and better your chances for saving the engine.
 
Another head casting to consider is #7120. Alot of people with stroker motors are using it.
 
0630s were 96-98
7120s were 91-05

But these don't have the bosses on them to install the coilpacks.

Kyung
 
Fish'nCarz said:
Enjoy.

http://www.naxja.org/forum/showthread.php?t=92545&highlight='01+head
http://www.naxja.org/forum/showthread.php?t=92253&highlight='01+head
http://www.naxja.org/forum/showthread.php?t=80757&highlight='01+head

Welcome to the ever expanding club of '99 + XJ's with bad head.

(Didn't think there was such a thing.)
Click to expand...

Unfortunately there IS and that's why I conducted a poll in NAXJA and in JU. The vast majority of heads are cracking after the 60k mile mark when the powertrain warranty has already expired. Worryingly, most '01+ 4.0 engines haven't passed the 60k mile mark yet so there's still potential for hundreds more 0331 castings to crack and rear their ugly head (pun intended ;)).
 
In answer to what I think you were asking with the original question....

If the only problem was a crack in the block, then replacing it will fix the coolant loss and make it quite reliable again. If there were other issues with the motor that caused the initial coolant loss, then, of course, those will need to be fixed as well.

Replacing a head is no big deal on the 4.0....the wife and I did out most recent one in about 5 hours total on the '89 Cherokee. The head was from http://cylinder-heads.com/ and they were good to work with. if you know what casting # you want...so much the better.

FWIW....I ended up changing the water pump, thermostat, hoses and eventually the Radiator while I was in there on my engine.....

Jim
 
mavinwy said:
In answer to what I think you were asking with the original question....

If the only problem was a crack in the block, then replacing it will fix the coolant loss and make it quite reliable again. If there were other issues with the motor that caused the initial coolant loss, then, of course, those will need to be fixed as well.

Replacing a head is no big deal on the 4.0....the wife and I did out most recent one in about 5 hours total on the '89 Cherokee. The head was from http://cylinder-heads.com/ and they were good to work with. if you know what casting # you want...so much the better.

FWIW....I ended up changing the water pump, thermostat, hoses and eventually the Radiator while I was in there on my engine.....

Jim
Click to expand...
Was you able to get a 7120, or 0630 from them? I can only find a listing for the 0331. I'm not going to waste there time contacting them to ask when I don't need one persay just being courous.
 
Thanks marvinwy
thats what i was wondering about, my only problem was just the crack, so guess the engine will be back to normal

had good oil pressure, idle 15-20, and was 48-50pressure, going 55-60miles an hour on highway.
 
I think that if you change the head and put in a greater flow water pump and a free flowing t-stat so you eliminate hot spots you should be good to go. At least that's my hope!!

I may be changing radiators at some time, but mine looks clean now.
 
RichP
yeh saw those alum heads, nice!!!!!!!
i want to keep my jeep a long time, but the regular cast iron replacement and labor is 1600 dollars , couldn't see spending that much on just the head and then labor on that. I want to do other mods. so trying to keep cost down for fixing it.
but would have been nice!
 
So are you just gonna put on another 0331 head and hope it doesn't crack for the next 60k miles or so, Or are you gonna adapt your coilpacks to either a 7120 or 0630 head?

Kyung
 
well the shop looked into the 0331 issue.
came up with , the head i got is 0331 but was cast within the last year.
as a replacement part through DC/jeep. so hopeing it is alright.
 
i have a 90 and i dident know i was out of coolant due to a radiator leak and drove it for 3mi. when i realized this i replaced the radiator and it worked fine. i thought i would have blown somthing.
 
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