rear main seal/main bearings

I decided to replace the rear main seal on my :v6: So I pulled my pan and rear main bearing cap. The bearing did not look to be in very good shape. It looks pretty worn.. so I took a pic to show you guys and see what you guys think I should do. The crankshaft jornal - I did not feel any grooves. The bearing.. small grooves and small rough spot.. which looked odd to me. I'm guessing this is still the standard sized bearing.. I dont know how I could measure the crankshaft while it's still in the motor. Also, I'm thinking its best to just replace it with a new standard size bearing. I found some Clevite 77 P-series main bearings on summitracing.com for pretty cheap. $34 a set. Anyone heard of these P-series type ? http://www.summitracing.com/parts/CLE-MS960P/

Heres the pic of the bearing..



Also doing the rear main seal.. I'm planning on springing for the rubber style.. hoping it'll be better and seal better. So, I plan to loosen the crankshaft by loosing the main caps and slide the new peice in.. does this sound like the proper way to do it ?

 

What was your oil pressure before you took the engine apart?

Looks like you have some scratches due to dirt/grit in the oil at some point. To me, it's not pretty but also not catastrophically bad. In theory, this is what the bearing metal is supposed to do - embed any foreign material rather than damaging the crankshaft.

Have you looked at the rod bearings? The rod bearings take more abuse than the mains, and are more often replaced with the crank in the block.

If it were mine, and I were convinced I needed new main bearings, I'd just pull the engine and install a crank kit with new rod and new main bearings. This would also give me a chance to measure the bearing clearances with Plastigage before I put the engine back in.

Regarding the rear main, I'm sure the FSM must have some instructions. Later manuals tell you to loosen the main caps for clearance.

 

My oil pressure was good. I had 30 psi at idle when warmed up. I do have a high volume pump kit installed. I agree it'd be best to pull the crank and check clearances and install all new bearings. Maybe even grind the crank if needed. But I've been working o this thing so long I need to drive it. Would I be ok if I put it back together an run it, then do the bearings over the winter ?

 

If it were mine, I would just put the seal in and put it back together. Since the oil pressure is good, I'd assume that the clearances are ok. Let sleeping dogs lie.

 

Probably.

The bearing looks sound to me. No base metal showing and only minor wear on the bottom. My guess this is from dry starts as much as anything else since you have been working on the vehicle and I assume it has been inoperative for long periods. As long as you pay attention, the worst that can happen is you will need to replace the crank/bearings earlier than planned.

 

New seal and drive it. I wouldn't be messing with it until the oil pressure falls or you start to get sound effects. I have seen way worse from still running engines.

 

Sounds good. Ill run the bearing for now. Thanks for the inputs

 

As A 20+ year Aircraft engine rebuilder, I also would replace the seal and run it!! So, 3X the above. Matt W.

 

Nice ! If all goes well I should be driving the cj this weekend.