More of an FYI than anything else. I estimate that my engine probably has >70K miles on it. When I got it, I noticed considerable movement from the flywheel to the main crank. Almost 3/8" it seemed like and noticable different engine pitch with the clutch put in. After consulting some of the guys around they said that a thrust washer had fallen out of crankshaft bearing in the engine and that I would have to replace it. Sounded 20 times more complicated than it was...

Basically, 1st gen Cummins have a bearing on the 4th bearing back (at least with a 4BT 3.9 liter) that is three metal pieces pressed into each other. When I asked about this at Cummins they had no idea what I was talking about and that the replacement part was one piece. They were right, because it is a poor design (namely, the washer can fall out of the bearing then you get the problem I had) the new bearings are one piece. I'll post part numbers when I get a chance...

I had never been in the bottom of an engine before so this was all new to me. An engine "bearing" is basically a special piece of metal that can handle the moving parts when used with lubrication (engine oil).

Item 1 is the lower bearing that fits into item three, the cap that bolts over the crank with bearings using 4, two pins that are torqued to 88 ft-lbs, then 129 ft-lbs.

The top bearing is number 2, and you can see the washer (pressed into the bearing as you can see the other washer in tact still). The replacement piece is smartly one piece. Unfortunately I forgot to take a picture of the replacement piece except for it installed.

 

Here is the bottom of the engine, you have to remove the oil pan (easy to do in my case, no need to remove the engine unless you have no space I guess). Watch out oil will be everywhere even after you let it completely drain out.

Make sure you are wearing rubber gloves and/or that everything is totally clean.

Then use a blunt but pointy object to slide the old bearing out. 1st, remove (in my case the fourth-back) bearing cap that has the two bolts. These are numbers 4 and 3 above. Then use a blunt (aka not sharp unless you are really careful object). I actually used a huge screw driver but just in case I put a rag over it to not scratch the crank, block, or bearings. But I would recommend something better though I know Cummins makes a SST for this.

Then, slide out the old bearing, take the new one, soak it in fresh oil, then slide it in the same way. There are grooves in the backside of the bearings so they will go in properly.

The replace the bearing in the cap with plenty of fresh oil, and bolt it all up, torque specs as said above, replace your oil filter, oil pan gasket (notice the oil pans are switchable frontwards-backwards interestingly enough. Use high temp silicone to seal it up, and if you are **** wait a few hours after putting everything back together before bolting up so the silicone can set and dry.

Fill with oil... Then, this is important (I think). Do not turn on right away. Disconnect the 12V wire to the fuel pump and use the starter to build up oil pressure. Then once you have oil pressure, connect the wire, start up and you are as good as new!

Here is a photo of the upper bearing installed: