5-Speed

I think I see what happened now. See how dark the sides of the bearings are in the rod caps for like the first 1/2"? Those are the .001 bearings right? If so, that tells me they were too tight and the scoring and pitting was actually due to galling from not enough clearance. I am guessing the other half of the rod bearings (STD sized ones) dont have those dark spots?

Spencer_P

99 engine with what looks to be dated 99 bearings. I just talked it over with someone a lot more informed than me and he also mentioned pulling the camshaft to check/replace the bearings. He thinks the damage to the underside of the CR bearings is from them being “stamped” against the CR cap not them spinning. He gave me a bore gauge and a micrometer so I will get some more accurate measurements tonight/tomorrow.

Yes, 5-speed, those are the .001” bearings. TBH I was in a rush when I removed the uppers (STD) and can’t say for sure what condition they were in. I can get pictures tonight. I’m still leaning towards these being the original bearings but that is based off what I assume is a date code. I don’t know for fact it is a date code but did see that mentioned in another thread.

Spencer_P

Upper CR bearings, worn but consistent.
Looks like cylinder five got the most damage across all the bearings.

Spencer_P

I mistakenly ordered Enginetech Aluminum Silicon rod bearings. They claim they are equal or better than tri-metal, what do you guys think? I don’t want to open them until I’m sure I shouldn’t return them. The Mahle crank bearings were damaged in shipping and have to be returned.

Spencer_P

Any suggestions on where to buy tri-metal rod bearings? RA only has sealed power that are standard and tri-metal. Summit doesn't look to have any standard tri-metal either.

5-Speed

Nothing wrong with the aluminum bearings if you go that route. The last Jeep engine I built, thats what I used.

If you want tri-metal, looks like Ebay has a couple Clevite sets. Not very cheap though...

CB960P and MS1947P

Spencer_P

Thank you for that, I will order the std rod bearings off eBay.

Are all camshaft bearings made of the same material? Any reason I shouldn't get the Enginetech ones? I can get Clevite ones off of Amazon for about $30 more.

5-Speed

Yep, cam bearings come in different materials and different widths. You dont need anything fancy.

Dura-bond actually makes good cam bearings too and they dont break the bank. Not sure if they make anything for the 4.0L though.

bluejeep2001

I thought you need specialized tooling to install/ remove camshaft bearings...you would need to get the cam miked to get the proper size

Spencer_P

RA does offer Dura-bond cam bearings. Actually two options.



I got an Amazon cam bearing removal tool. I only see standard cam bearings and the camshaft looks good but I will measure it as well.

5-Speed

Get either. The grooved ones are nice but not really needed. If they are only a couple $ more, I would go for them. Cam bearing install isn't really straight forward so if you have questions before you do it, just post them. Easy to walk you through it

Spencer_P

Only $2 more, I'll get them. I appreciate all the help!

Spencer_P

I've been busy with work and travel and it has been in the single digits here so I haven't made any more progress.
I'm eager to get back to work as my weekends start clearing up and it warms up a little.
If I do end up needing to mix bearing sizes, which the FSM says is acceptable, do I need to order 6 sets of undersize or can I just get 3 sets to get the 3 halves I need?

bluejeep2001

When you say 3 halves, do you mean to mismatch 2 different sized bearings in one hole/ journal or just replace 3 of the bearings out of 7

Spencer_P

All of the bearings will be replaced. If I need to use the same size connecting rod bearings I removed, undersized on one half (half being upper/lower) and standard on the other half, can I buy 2 sets (4 halves) of undersize bearings and have the sets spread across the 6 connecting rods? I believe I can because the two halves look identical. I have already purchased the standard set from ebay mentioned earlier but if I end up needing undersize I'd rather buy 2 sets than 3 if I can.