Pilot bearing consists of 1B3740 race and 1B3739 roller assembly.
Not much you can do about real main bearing leakage. There is no seal, just a helical grove that is supposed to return any oil that gets past the bearing to the sump. Excessive bearing clearance and clogged return grove makes things worse.

You should fix the pinion while you are in there
Chuck C

Hi Team,
with these old girls if you have Diesel Engine oil transferring into the clutch compartment the No1 first thing to check is the Diesel Engine crank case breather for restriction/clogging with dust--it is a cleaning requirement to be carried out at each Diesel Engine oil change period-- at either 250 or 500 Hours depending on the oil used--as per my Grey OMI for the U series D2, Form No 10953-10.
Also use of non-detergent oils in the past could possibly block/restrict the scroll oil drain back drilling in the rear main bearing cap.
Cheers,
Eddie B.

Old wrote:

Pilot bearing consists of 1B3740 race and 1B3739 roller assembly.
Not much you can do about real main bearing leakage. There is no seal, just a helical grove that is supposed to return any oil that gets past the bearing to the sump. Excessive bearing clearance and clogged return grove makes things worse.

Thanks Old Magnet! Sorry if this is a stupid question but, Is there a way to clean the oil return groove without removing the crankshaft? The service manual for the d311 mentions some 'packing' that can be done. Is this referring to a graphite rope seal.

Yes, ChuckC, I plan to do a major starter pinion overhaul.

Thanks edb, I will certainly investigate the oil breather and make sure it's clean.

Rope packing referred to is for around the outside of the rear main bearing cap. Has nothing to do with crankshaft sealing.
No way of accessing the oil return groove.

Hi Team,
Search seems to work OK now so here is are the charts recently posted on Ball and Roller Bearing Conversions.

www.acmoc.org/bb/discussion-d72/26787-ca...g-conversions#219292

Cheers,
Eddie B.

I got the pressure plates resurfaced now and a new clutch disc. I'm looking to replace the 3 springs and hardware now, that separate the pressure plates. I was able to source the springs 0L-1466 and washers 4B4274, but I'm having trouble finding the pins, part number 4B9098. Dana at Florin tractor couldn't locate any and neither can Caterpillar parts.cat.com. Anyone know a suitable replacement for the pins? I'm honestly not even sure how to dismantle them without cutting. Any guidance is appreciated!

a good detergent oil overtime may clean it out. but it would be best to do it properly with the bearing removed you may be able to use fine stiff wire to clear it.
this groove also allow the rear bearing to be lubed.

Take a good look at the starting pinion while it is wide open and easy to get to. I don't think a D2 has a true rear main seal per say. I think they have a slinger that throws the oil forward when running. Somebody smarter than me should pop up with more information on that.