• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Pictures of cracks in 4.0L engineDoes anyone know of a site where there are pictures

oldbill

NAXJA Forum User
Location
Michigan
Does anyone know of a site where there are pictures of the cracks that appear in some 4.0L heads that cause problems. Supposedly these cracks are the result of over heating. Cleaning up the surface of my 4.0 head while replacing piston I've noticed what might be a small mick, it is within the inside of the sealing ring on the head gasket. It almost appears to be just a surface scratch and doesn't appear to be seen of felt in the combustion area. At this point being retired I'm a little tight on money to have the head machined or buy a new one. If I can go as is I'd like to, but am looking to the experts for answers. If it would help I could try to post pictures tomorrow. I not the first owner of the Jeep but have had it for a couple of years and it has never over heated or lost coolant. Engine has around 190000 miles on it. Bearings and everything looked good. Put in a re manufactured crank due to the cost of the odd size main and rod bearings.
Thanks,
Bill
 
The heads most prone to cracking are the 0331 heads in 2000-2001 vehicles. The 0331 is on the drivers side top edge of the head near cylinders 3 & 4. Updated heads are still cast with 0331 but also say TUPY in between the rockers for cylinders 3 & 4. When it cracks, there is usually a visible hairline crack, a "tan line" (contrasting color to the surrounding area), bubbles in the oil, or worse, visible coolant in the same area that the new heads say TUPY.

All the heads can crack and there are pictures on the Internet that show 0630 and 0721 head cracks, but these are usually from some other issue, such as a massive overheat.

It sounds like you have a scratch rather than a crack.
 
Does anyone know of a site where there are pictures of the cracks that appear in some 4.0L heads that cause problems. Supposedly these cracks are the result of over heating. Cleaning up the surface of my 4.0 head while replacing piston I've noticed what might be a small mick, it is within the inside of the sealing ring on the head gasket. It almost appears to be just a surface scratch and doesn't appear to be seen of felt in the combustion area. At this point being retired I'm a little tight on money to have the head machined or buy a new one. If I can go as is I'd like to, but am looking to the experts for answers. If it would help I could try to post pictures tomorrow. I not the first owner of the Jeep but have had it for a couple of years and it has never over heated or lost coolant. Engine has around 190000 miles on it. Bearings and everything looked good. Put in a re manufactured crank due to the cost of the odd size main and rod bearings.
Thanks,
Bill

Have a picture, but can't seem to find a way to add it.
 
Upload it to imgur.com and post the code here. It's pretty self explanatory but if you get it wrong, we can probably still fix it up.
 
Magnetic particle inspection doesn't work on aluminum. Magnaflux (brand) sells a nuke grade dye kit that is mentioned above that uses a cleaner, penetrate and a developer.
 
Magnetic particle inspection doesn't work on aluminum. Magnaflux (brand) sells a nuke grade dye kit that is mentioned above that uses a cleaner, penetrate and a developer.

100% correct, but the 4.0 head is cast iron.
 
jeez, I am such a noob.. I am trying, honestly.

No worries. I've actually had people tell me that I should magnaflux an aluminum head before :laugh2:
 
Crack is vertical in this picture. Water jacket hole to water jacket hole between cylinders 3&4. 0331 head from 2000 Sport with 141K miles.
2014-02-11200940_zps831f5f49.jpg
 
That certainly looks like a crack to me. You could go the machine shop route and have them test it, or you could get a Chrysler TUPY head, or a Clearwater, ACH, J&C, National, .. head. If you start looking at junkyards, any head from 2002-2006 will work. If you look for 1999 or earlier heads you'll need to deal with manifold differences and figure out a way to secure the coil pack to the head because the bosses were added in 2000. NAXJA and other forums have many posts describing the options.
 
Guys, that's someone else posting an example pic, not the OP :spin1:

(I almost said exactly the same thing.)
 
Back
Top