Main Bearing Issue

[spectre6000]

I had a pretty decent leak coming from the back of the engine, and it turned out, not surprisingly, to be the rear main seal. I got it all down to replace it, and sure enough, it was installed level with the bearing cap and without any sealant to either side as per the manual. That explains the leak pretty handily. Additionally, whoever replaced it last must not have loosened the other bearing caps because the outside of the seal looked like it got scraped a bit going in. Whatever, that's why I'm in there replacing the thing. Nothing really unexpected to this point.


What was a little less expected was the smell of burnt oil. It seemed to only smell of burnt oil when removing the bolts from the rear main bearing, and I don't think there was any smell associated with loosening of any of the other bearings. My burnt oil smell experience comes from severely overheated air cooled engines in case that helps with reference; it could be that diesel oil just smells a little like burnt gasser oil and I hadn't noticed to that point. The real kicker came when I wiped it all down... The plating has flaked off the bearing a bit...




That's a pretty pisser right there... I can feel it when I run my finger along it, but it's still slight. I checked the crank journal (the half I could see anyway), and there's a VERY slight amount of yellowing where it would be running through that mess, but it's so slight that I probably wouldn't have noticed it at all had I not been looking in that exact spot. It's still good and smooth. The truck only has some 30K miles on it, so this must be another of those things I didn't expect would happen from sitting... Not sure how yet, but I'm sure someone will tell me.I buttoned the mess back up in a holding pattern until I can figure out what to do with it/order parts/who knows. I would have just left it as is, but oil still seems to be finding its way out and some tree or something is putting a bunch of fuzzy things in the air, and they seem to stick pretty well to anything even remotely oily.


So what's the advice from those who have been here and seen this? Run it? Can the main bearings be replaced without a complete tear down? Should I just suck it up and try to rebuild the thing in the truck? What?

 

[dependable]

Hard to know how bad it is without seeing. You could check bearings clearances with (drawing a blank here, those plastic ribbons of different colors).

Is oil pressure OK?

Anyway, if you are going to get that far into it, and the top end of the motor is good, would advise buying a 'crank kit', that would be a reconditioned crank shaft with matching bearings. While you are at it, change the oil pump too.

Would not advise lower engine work without removing motor from truck.

 

[spectre6000]

I assume oil pressure is fine. It's still fairly stock and I've only driven it a few hundred miles (home from purchase) and to the tire shop, and it seemed fine save a fuel delivery issue from sitting and probably because the additive I used knocked some junk loose. It honestly seemed pretty fine on the whole save the things I've already addressed or are in the process of addressing. Said another way, the idiot light never turned on.

I talked to a friend on the phone who was a diesel mechanic in the Marines while these were still around, and he said the reason the bearing doesn't look happy as described is probably because it didn't get proper oil pressure due to the previous rear main seal install being botched and allowing it to leak over at least a few thousand miles. From the sound of it (my description on the phone), he said it was probably nothing to even worry about, but since I'm already in there I might as well replace them. He suggested rolling in a new set. I'm still doing my best to figure out what that means exactly from his description and what I can find online.