D21 Engine -Buy Used? or Buy Crate? or Re-Build

Information on the naturally-aspirated KA24E and KA24DE engines.
Palmetto Owner
Posts: 2
Joined: Thu Aug 23, 2018 4:10 pm
Car: 1994 Nissan Pathfinder
1993 Nissan D21 Truck

D21 Engine -Buy Used? or Buy Crate? or Re-Build

Postby Palmetto Owner » Sun Jun 12, 2022 4:35 am

I love my 1993 D21 (and KA24E engine) for a lot of reasons (no time for a life story here). However I just destroyed the thrust bearing (which is the center main bearing). I was driving home from work when the oil pressure dropped from 35 to about 15 psi. I dropped the oil pan to check the rods and mains and they felt solid. I removed the valve cover and everything looked ok in there. I installed a new oil pump and at the last minute before replacing the oil pan, I decided to check the crankshaft end play and it was .060"
I posted a photo below, and you can see that the thrust bearing metal is worn off but not through the steel backing, so the bearing cap is not damaged. The front thrust surface is fine. The wear happened on the back thrust bearing... maybe consistent with a clutch problem.
I'll see in the daylight tomorrow if the crankshaft thrust surface is scored.
My first choice would be to pull the engine and rebuild it. I can buy a new crank if necessary.
However my local machine shop has a three month backlog (and actually probably longer) just to bore the block and I need to be back on the road sooner than that.
I had a quote of $1720 for a 1995 engine with 94,000 miles, but there are a lot of uncertain things with a used engine. Also the reviews for the company had a lot of complaints about communications and also how long it took for their engines to be shipped out.
A. - Can anyone recommend a good machine shop that can turn a block and heads around in perhaps 30 days or less, within driving distance of South Carolina (300-400 miles would be OK)?
B. - Can anyone recommend a used engine vendor known to be trustworthy and reliable and possibly a forum member or vendor?
Another choice:
C. - Buy a new crankshaft if necessary and replace rings, rod and main bearings, remove any top cylinder ridge, ball hone the cylinders and hope for the best.
and last choice:
D. - Does anyone have experience with a rebuilder with a good reputation for selling re-conditioned engines?

I would really enjoy a discussion of why this failure happened, but right now getting back on the road is more important.
Center Main Rear Thrust Surface.png
Rear thrust is shot
Thrust Bearing Front.png
Front thrust is good

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