Re: Blown head gasket on 98 cherokee?
 

What is the weakness ?

Dave Milne, Scotland
'91 Grand Wagoneer, '99 TJ
"Simon Juncal" <SPAMERSSUCK@usefirstinitialandlastnameATerols.com > wrote in
message news:E8WdnUdLjrVXYLPYnZ2dnUVZ_sadnZ2d@rcn.net...
> I would suspect the head is cracked, not the gasket blown, the 0331 head
> is notiorious for cracking due to a weakness Jeep introduced.

Re: Blown head gasket on 98 cherokee?
 

What is the weakness ?

Dave Milne, Scotland
'91 Grand Wagoneer, '99 TJ
"Simon Juncal" <SPAMERSSUCK@usefirstinitialandlastnameATerols.com > wrote in
message news:E8WdnUdLjrVXYLPYnZ2dnUVZ_sadnZ2d@rcn.net...
> I would suspect the head is cracked, not the gasket blown, the 0331 head
> is notiorious for cracking due to a weakness Jeep introduced.

Re: Blown head gasket on 98 cherokee?
 

What is the weakness ?

Dave Milne, Scotland
'91 Grand Wagoneer, '99 TJ
"Simon Juncal" <SPAMERSSUCK@usefirstinitialandlastnameATerols.com > wrote in
message news:E8WdnUdLjrVXYLPYnZ2dnUVZ_sadnZ2d@rcn.net...
> I would suspect the head is cracked, not the gasket blown, the 0331 head
> is notiorious for cracking due to a weakness Jeep introduced.

Re: Blown head gasket on 98 cherokee?
 

Dave Milne wrote:
> What is the weakness ?

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.

--
Simon
"I may be wrong, but I'm not uncertain." -- Robert A. Heinlein

Re: Blown head gasket on 98 cherokee?
 

Dave Milne wrote:
> What is the weakness ?

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.

--
Simon
"I may be wrong, but I'm not uncertain." -- Robert A. Heinlein

Re: Blown head gasket on 98 cherokee?
 

Dave Milne wrote:
> What is the weakness ?

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.

--
Simon
"I may be wrong, but I'm not uncertain." -- Robert A. Heinlein

Re: Blown head gasket on 98 cherokee?
 

Dave.

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
overheated.

Joe R, Ohio, USA
06 CRD Liberty.

"Dave Milne" <jeep@_nospam_milne.info> wrote in message
news:e2GXg.34444$r61.918@text.news.blueyonder.co.u k...
> What is the weakness ?
>
> Dave Milne, Scotland
> '91 Grand Wagoneer, '99 TJ
> "Simon Juncal"

Re: Blown head gasket on 98 cherokee?
 

Dave.

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
overheated.

Joe R, Ohio, USA
06 CRD Liberty.

"Dave Milne" <jeep@_nospam_milne.info> wrote in message
news:e2GXg.34444$r61.918@text.news.blueyonder.co.u k...
> What is the weakness ?
>
> Dave Milne, Scotland
> '91 Grand Wagoneer, '99 TJ
> "Simon Juncal"

Re: Blown head gasket on 98 cherokee?
 

Dave.

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
overheated.

Joe R, Ohio, USA
06 CRD Liberty.

"Dave Milne" <jeep@_nospam_milne.info> wrote in message
news:e2GXg.34444$r61.918@text.news.blueyonder.co.u k...
> What is the weakness ?
>
> Dave Milne, Scotland
> '91 Grand Wagoneer, '99 TJ
> "Simon Juncal"

Re: Blown head gasket on 98 cherokee?
 

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

Jeff wrote:

> 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.)
>
> Questions:
> 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?