Engine Condition Input

[geunther]

My engine/transmission were leaking so I pulled both to seal them up. Both are original to the truck and in good shape. The engine has good compression, runs great. Really the only issue was oil leaking.

I pulled the rear main so I could replace the seal. The bearing does show some wear as you would expect. The bearing markings (GMM) indicate likely a factory bearing which matches the date code. The bearing size shows 001.

Now, I was hoping to replace rear main seal, new pan gasket and move on. With the bearing wear, should I replace the mains or does it look fine for the next 10k miles or so to you guys with a lot of engine experience.

Also, assuming its a no brainer to put in new oil pump?

[truckster]

It depends on how much you want to do to it. You could reseal it and run it. Or you could Plastigage all of the bearings and see where they're at. The problem with that is that you might find one that's a little more worn than you're comfortable with, and the next thing you know you're at the machine shop dropping some serious cash.

[geunther]

Originally Posted by truckster

and the next thing you know you're at the machine shop dropping some serious cash.

Don't I know it. Im 8 months into a rear main seal change.

[1970-CST]

Package it up, and leave well enough alone. Bottom ends seldom fail, short of abuse and or oil starvation. The top end will go long before those bearings do.

[BigBird05]

How was the oil pressure before you tore it down? If it was good run it.Unless you drag racing.

[YellowK5]

Put the seal in it and run it!....

[truck-kid]

How was the hot oil pressure ? if it was acceptable l agree with others put a seal in it and run it.

[burnin oil]

If the oil pressure was good I would just reseal. Replacing the rear bearing may be a good idea though. It is the thrust bearing and usually has the most wear. If its a stock truck replace that one bearing and roll on. After all you are already pulling that one cap to roll the seal in. The bearings can be done the same way. It used to be common to do a backyard rebuild and just rering and new bearings. I just did a jeep 4.0 that way. Runs great.

[HotWheelsFan]

The bearing shown looks fine. I would feel comfortable doing a reseal...

As mentioned above bottom ends have less trouble, unless you run your engine hard and with low oil levels.


In my signature links you can see my truck where I did the same with my truck... Pulled one head for inspection and just replaced seals.

Bob

[jimijam00]

10K miles or so? Does this mean the truck has an experiatation on it and you'll be ditching it? Or does this mean you are simply kicking the can down the road? I'm NOT a fan of kicking the can down the road.

[57taskforce]

Run it. I build them for a living, there’s nothing I see scary there at all. Oil pump isn’t a bad idea but for only 10K more miles I don’t think I’d do anything to it if it wasn’t showing any obvious signs it needed replaced.

If oil psi was an issue before the tear down it is very unlikely to be from that bearing.

[geunther]

Thanks for the input. New seal is in, cap torqued. Just waiting for the new oil pump only to replace the original. The plastic shaft connector was brittle and now broken. The seal was fairly brittle as well (hence the leaking oil).

The oil pressure was always fine, cold or at temp. My hot rodding days or over and now I am about longevity (me and my truck . The engine appears to never having been rebuilt so I only mentioned the 10k mile rebuild because I'd probably rebuild it when and if it starts using oil, fouling plugs etc.

As clean as the engine and tranny is, I cannot imagine that neither have been rebuild, though I can not find any indication that either has been. Except maybe for the 001 bearing. Maybe they put those in at the factory depending on tolerances?

I am resealing the transmission as well without a rebuild. My theory is the transmission leaked so badly it always had a supply of fresh fluid.

[Steeveedee]

It was quite common for the factory to put in an oversize bearing on a single journal if it took an extra cut to completely clean up.

[kwmech]

I'd put it back together they way it is and run it. BUT I would ditch using Fram filters

[custom10nut]

When I rebuilt my 350, I found out that the crank bearings were originals.
Now mind you, the engine had 159,000ish miles on it, but I also have receipts that show it was “rebuilt” by the second owner.
When I tore it down, the Machinist informed me that all the Cylinders Mic’d different readings, BUT the Main Cap Bearings were FACTORY.
Anyway, as long as your not racing at the Speedway, put it back together and enjoy driving it.

[bob arrington]

something I have done with some success is to replace used bearings with the same size new bearings without doing any machine work, in a few cases it got rid of more than one of those real light rod knocks and helped avoid that reused spun bearing 'gotta pull the engine again' issue. hope this helps
back in the day, I'm 70 now, when you did that laying under your car, it was called 'rolling new bearings in'