New to the forum and new to Jeeps. I have a question for you all. I'm rebuilding a 4.0 out of a 2000 xj. It had a noise (piston skirt) that was in between a lifter tick and a rod knock not to mention a cracked head (yep got it cheap). upon disassembly I noticed that the oil slits in the main bearings did not line up very well with the the oil holes in the main bearing saddles. the new bearings (federal moguls) are the same. I've built an engine or two in my time and have never seen this issue(?) with a bearing nor did I find a solution using the search. I've seen all sorts of threads this forum for swapping out bearings and rebuilds but no mention of this (to me) issue. Pics aren't great but take a look. I've never had to make modifications to bearings before not counting cam thrust bearings on VW engines. Is this common on the 4.0 and what do you all do to rectify the situation?

 

Looks pretty normal to me. I'd guess that 99.5% of the oil hole is exposed by the slot in the bearing, not worth modifying either for that last 0.5% IMHO.

 

Agreed. The slot being long enough to accommodate other installations doesn't bother me either.

And welcome to the forum Slow...There is plenty to be brought up here. Google "0331 head". When they crack between 3 & 4 coolant might get in the oil. I was doubtful at first, but it seems coolant does indeed do nasty things to bearings. Might be if a cracked 0331 head is not caught in time the whole engine might be in trouble. Part of the booger is yes, you can do rods and mains, but the stupid cam bearings might ding your oil pressure.

Good Jeepers always check their torque converter to torque plate bolts as they are known to loosen and cause a knock.

There are no factory improved "TUPY" 0331 heads in our Jeeps. They are in Grands and others. The "Tupy" foundry mark can be seen with the oil filler cap off. (I hear).

I Googled it> https://www.google.com/search?hl=en&...pe=&as_rights=

 

I picked up a new bare casting from some tool supply company in the Midwest that also sell heads. Its not a TUPY casting but it's not a 0331 either, maybe be a Chinese job but it look like a better casting that the 0331. No bearing slam and go here, the block has been hot tanked, sand blasted, plugs pulled, all galleys cleaned, bored, honed, and new galley plugs and cam bearing pressed in. The crank has been ground and polished and I have a new cam sitting on the bench. I figured the cracked head wiped out my cam lobes and bearing and diluted the oil top the point that the ring had a little to much friction causing the piston slap to crack the skirt. The bore had a lot of wear for only 160k, had to bore .30 over.

 

Sweet! Sounds like you know your way around. Since you are going there you might check out the paint job crusier did on his stroker.

The heads changed between 99 and 2000 I think. Exhaust ports don't line up right with a 2000 head on a pre 2000. You might watch for that...anyway you may well be ahead of me. Just know they don't swap without a converter plate, (or some such)

The sensors need to match your puter, and the puter needs to match the Jeep. I just bought a steering box at a JY off a jeep someone mixed that one up with and couldn't pass smog. Stretching my knowledge here, but you may want a head that 2000/2001 manifolds, (with their sensors) bolt's up to. CCken here, amognst others would know more than I do.

 

The cracked skirts aren't entirely uncommon, but that much bore wear that soon sure is.

If you don't mind, perhaps posting the source of the new head might help the next guy looking for one.

 

The name of the place is Craig's affordable tools. It is sold as a replacement for the 0331. Not sure how the head will work out but the casting did look better than the 0331 and everything including the exhaust ports are in the same location as the 0331. http://affordabletool.com/fall-auto-...FYeVfgodyM0Hxw