My 1998 Jeep Cherokee L6 4.0L started missing badly the other day, so I
checked the codes and got the following: 300 (random misfire), 301
(miss on #1), 303 (miss on #3), 304 (miss on #4).
So I took it to my local shop and rode my bicycle home. This morning I
got a call from the mechanic, and he says that the issue is a blown
head gasket, and mentioned that "sometimes these have a cracked head
too." He also reccomends a valve job as it has 145,000 miles on it.
I'm wondering what to do here. I like the vehicle, but I probably
should have traded it in for another one 20,000 miles ago.
They are quoting me $1400+ for the gasket replacement (and I think that
includes a $350 valve job.)
What are prices that people have experienced on this job?
Is a cracked head really likely on this?
I am fairly mechanically inclined, can I fix this myself?
How long would it take to fix myself?
Yes, you can remove the head and replace the gasket, and NO, you cannot do
the valve job.
That being said since you already have the head off to replace the gasket
you can take the head to an automotive machine shop where they can inspect
the head and make any necessary repairs and then return it to you ready for
There is no reason to replace an XJ Cherokee at 125,000 miles unless it was
struck by a meteor or a cement truck. That model will usually go 200,000+
miles before it requires any major repairs.
Be sure to change the oil and filters every 3000 miles with a good quality
oil and filter.
Be sure to get a quality gasket set, don't try to save a nickel here..... (I
got my FelPro gaskets at the machine shop)
Some engines require replacement head bolts.
You can ask for names of reliable machine shops at your local auto parts
For a plain head gasket replacement, figure something like $250 to $350
for a decent valve job with a couple of new valves, about 4 hours labor
to pull and replace the head. Fairly reasonable DIY job for the labor,
figure a long day if this is your first try at it. But at $1400, I'd at
least find another shop to work on it.
I'd think about skipping the valve job if possible.
If they're not hurt, leave them alone.
Sometimes fresh valves with nice tight combustion chambers and 145K old
rings don't play well together.
That's a very good point, if the rings are worn and all of the sudden
the top end is nice and tight it could start pumping oil. If the oils
been changed regularly that shouldn't happen but it could.
If the engine was running well before this happened I'd clean everything
up, make sure the head surface was flat and put it back together again.
Well, I shopped the job around and found a place that will do it for
$550, add a valve job for $50 more. Its a reputable shop that my dad
reccomended. Heh, leave it to the old man.
Off the original subject...
I drive a ridiculous amount of miles to work, ski, mt bike, camp etc,
etc. The Jeep is pretty good for this stuff, but I put a ton of miles
on it. It's worth more to me running than as a trade in, so how long
should I expect to drive this? I figure after it's fixed up this time,
it can make 200K. I've heard stories of further... do I push my luck?
or do I think about moving to a 2001 Cherokee?
Oh, and I'm in South Central Wisconsin
I did the water pump last year, the body seems to be in great shape. I
think the last owner kept it in a garage, as do I, and that should
ssignificantly extend the life of the body on any vehicle in this area.
There are lots of guys on this forum that have 250-300k on their 4 liter
engines, just remember to change the oil and filter every 3k if you want to
keep the Jeep forever.
And yes, sometimes Dad's do know something.... you pick up a lot of stuff if
you live long enough....
Jeff, My Cherokees 4.0 finally started rattling a rod bearing after
about 300,000 miles of hard driving with oil changes that were not as
regular as they should have been.
I put a top quality rebuilt engine in it and am going for 600,000, it's
the best car I've ever had.
I'm also a LOT more careful about the oil changes, and using better oil.
I would suspect the head is cracked, not the gasket blown, the 0331 head
is notiorious for cracking due to a weakness Jeep introduced.
If you pull that head forget about a valve job, get a reman'd 0630 head
(an ealier casting that flows just as well but doesn't have the
weakness)... It's an easy job, if you're familiar with the 4.0
If you want very Cherokee specific advice check out naxja.com forums
they know everything you could ever want to know about an XJ there.
Including exactly where to look on the head to see if it's cracked (I
seem to recall it cracks at the 3rd cylinder intake pushrod hole and
rocker arm tower but I could be mistaken.
A 2001 will just be adding the possibility of the same problem on a more
expensive XJ (it has the 0331 head)... I wouldn't hesitate to spend $200
on an 0630 head (Ebay) and do the work yourself It's really nothing
scary just a lot of unbolting and rebolting using torque specs. Label
your loose connections and keep a chiltons or Haynes manual near by. You
can do it in a day if you attack it with confidence.
"I may be wrong, but I'm not uncertain." -- Robert A. Heinlein
I would do a search on naxja.com using the casting number you're sure to
find the definitive answer, apearently it cracks quite frequently. I
believe they cast it with less material in the pushrod holes (bigger
holes?) or it was a water jacket that had casting "drift" and got too
close to the outside world near the 3rd cylinder. I seem to recall
something like that but as they say: I'm not for sure on that. I only
followed along enough to find out the 0630 head and 7120 head don't have
it (and flow just as well acourding to HESCO); when I was researching
the 4.0 H.O. to 4.2 block head swap. This was a couple years back so my
memory has only retained the important part; avoid the newest (and last)
4.0 head casting.
"I may be wrong, but I'm not uncertain." -- Robert A. Heinlein
They redesigned the head for emissions I think. The 0331 heads started in
late 99 model XJ's. They crack easy if they're overheated between the center
two cylinders on the top as I recall. Also they seem to be ok if not
Joe R, Ohio, USA
06 CRD Liberty.
make dam sure they use the updated valve springs when they do the valve job
for that year since there was a issue of the springs not being strong
enough to knock of the carbon build up off the valves causing a misfire
code issue there is a tsb on this issue
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