nrider42

Hello,
I am in the process of building an SP2 car for PCA racing next year. The donor car is an early 85 US car. The motor has a questionable history. I have receipts from PO detailing a rebuild which included new rod bearings and main bearings. The story is that it was only driven a couple of times (no track, < 100 miles road duty) after the rebuild. I have completely torn down the motor and am not impressed so far. I was really not impressed when I took the crank girdle off saw the main bearings. I have attached some pictures to this post. They are heavily grooved, worn, pitted, scratched...I'm running out of bad words. There is bearing material in the sludge at the bottom of the pan (How did that sludge get there after a fresh build?). The rod bearings are not bad, they show minimal wear and do not show signs of being over heated. Unfortunately in the destruction induced haze, I can't say for sure which position the bearings came from. I need to take more pictures...






How do main bearings get trashed like this?

Any thoughts are welcome.

Thanks,

Nate

V2Rocket

if they were in fact replaced once upon a time, i wonder if they forgot to use assembly lube.

931guru

If it was rebuilt earlier due to a trashed #2 rod bearing, they didn't clean all of the crap out of all of the parts (oil cooler, crankshaft, block) before reassembly.

Jfrahm

Bent crank, maybe hydrolocked?

StoogeMoe

What does the crank look like?

nrider42

Thanks. My big concern is whether or not this engine has a fundamental problem. I don't want to spend a lot of money and time rebuilding it and have it grenade going into turn 1. The crank is not scarred too badly but probably need polishing. I will measure the crank and the bearing mounts carefully. Is a check with a straight edge on a crank good enough for straightness? What can I look for?

Thanks,
Nate

Edit: The crank has scratches which I can feel with my fingernail and are barely visible to the eye. I am not sure what polishing will do. I also know that the only oversize bearings I can find are expensive

tempest411

Depending on your philosophy, it's probably best to get another crank, and COMPLETELY strip and clean the block. Because I wanted to be super picky, it cost me almost $1500 to have my crank machined undersized, re-hardened, and purchase undersized main and rod bearings. Actually, it cost me more than that. It's probably best if I don't ever recall exactly.

Raceboy

My take would be that wrong size bearings were used. Perhaps crank was ground to 1st oversize but bearings standard -> such heavy damage.

Usually 944 main bearings are so strong that unless you have lost all your oil pressure there is no need to change them even until the you ave gone through few sets of rod bearings :P

curtisr

For your PCA efforts may I politely recommend either an oil accumulator (Accusump, etc) or baffles, scraper and the like in case you weren't planning on including these.

nrider42

Thanks! My plan is to run the baffle and a crank scraper. I took some pictures of the crank last night and attached them here. What do you think? It doesn't look that great to me but I am a newbie to engine building.

vetter59

I just rebuilt a '88 n/a engine and you crank doesn't look to good either, the problem with going to 1st over on it is the cost of the new oversize bearings. There are plenty of good standard size cranks out there for sale for $150.00 or less, and the cheaper route to.go. How do your bores look in the block?, you had to have a lot of metal particles floating around in the oil, looking at those main bearing pictures. Probably the cheapest way out of this situation would be to buy a good used short block-

curtisr

As I am, too. However this very same job awaits me (and the Spring) so I will follow along with interest.

jderimig

I'd curious as what others who have experience will say too. Can't tell from the pics but if those scratches are not too deep they may be able to be polished out and still stay within the factory clearance tolerances with I think are around +/- 0.002".