Thread: Bearing failure. What caused this? (pics inside)

Ok so after about 1300miles of running in (progressively harder and harder) and after a full tune I ran bearings on my built motor. Have an AFR gauge in the car and the AFR's was never richer than 11.5-12 during this running in phase.

Decided to pull the lower oil pan today to see what's up. Came accross this:












This was on a built motor with knife edged 4cw crank revving to about 8800rpm only. Manley rods. (Someone told me the forged rods don't have some extra oil hole that the stock rods have and this might be an issue??. Any truth to this?)

Also, the bearing ran on No 1 rod as far as I can see. It feels pretty loose when I move it. I can't access no 3 or 4 rods yet as I haven't pulled the lower aluminium oil pan but no 2 feels solid. It's very strange to me that no 1 went. This is not usual for SR20's afaik.

I changed oil about 6 times during the 1300 miles and also right before the dyno. AFR's in the mid 12's on WOT and around 14.5 elsewhere. 12.2 or so on idle.

Any idea what could have caused this?

Also, looking at the amount of debris in the sump, any chance my new rods are still fine? If they are then I'm considering just pulling everything from the bottom, putting in a stock 8cw crank with new bearings and a new oil pump. If the rods are damaged I'll need to pull the head which means new HG and a lot more work, in which case I may just opt to drop in a stock det.

This has nothing to do with AFR's, also nothing to do with using a 4cw.

Is that not part of your thrust washer in the sump?

I have a feeling that this is due to installers error!! If the thrust washer was fitted the wrong way round, it would cause something like this.

The thrust washers were destroyed resulting in crankshaft end float too big putting strain on the big end bearings! Some damage is going to be evident on the side of the main bearing journal where the thrust washers fit and would have to be machined as well.

If that is the case then oversize thrust washers would be needed.

what type of oil and changing the oil six times is nuts

For one, Aftermarket rods have nothing to do with an extra oiling hole. Rod bearings are fed by the crank. Seems like an install mistake or bearing size mistake. What bearings are those, Judging by the material probably oem nissan bearings.

Lots of things could have caused it. Low oil pressure due to a clogged or blocked pickup tube, cracked pickup tube, Over or under torqued rod bolts. Wrong size bearings, In correctly installed thrust washer putting a weird stress on the rods and bearings.

You will have to pull the cap and see how bad the damage is. If it was ran for a while like that then the rod is probably out of round im sure. It doesnt take long. Basicly you are looking at having to dissasemble the entire motor. You can torque down the rod caps to spec and have them measured for roundness. If the bolts were overtorqued then its almost certain the rod big end is out of round as well as if the knock was very very loud and for any decent amount of time and rpm.

Could have been shavings or stuff in the cranks oil port from the knife edging process. I always run cleaner and compressed air through all my cranks before installing just to make sure. Ive yet to ever have a bearing failure like that and some of the engines ive built rev past 9k all day long.

Something went wrong during assembly more than likely. Bearing shouldnt fail that early on if properly done.

thats a piece of the thrust bearing in the pan. if that came out bad things follow. I would pull the rod bolts on #1 and measure for stretch. If they are out of spec they were over torqued which will destroy the bearing quick.

read my sig. im sure "david NA" will just tell you to put new bearings in and you will be fine.....

anyways like they said if that thrust washer failed or someone failed at putting it in that sure would cause all of that.

you will need to have your rods checked for out of round. i can pretty much promise you they will be out of round. you dont need new rods but you will need to get them machined and get bearings to match. your crank is gonna be trashed too. have someone measure everything. thats your best bet.

Its not a thrust washer. At least I don't think it is. Its too thin and small and I couldn't feel any play on the crank.

Gonna pull everything apart tonight this w/e and take it from there. Bearing spun on the freeway and I had to limp home for about 2km. So the knock was very loud by then. Have a new crank ready to go but yes we gonna measure everything up and have it machined if needed. I hope the main bearings are ok. Any chance of them going out of round from this?

Trust me, everything was assembled perfectly. Clearances were perfect. I "think" I might have overtorqued that rod, then loosened and retorqued it. I'm not sure though.

main bearings should be ok as long as nothing went through them. obviously check them when you pull the crank out. the clearance had to be off or you had to have had oil starvation or something along those lines for that to happen.

could turning over the motor by hand against a piston stop damage the bearing at all? Had to do this a few times when doing cam timing.

no. unless you didnt use any assembly lube lol. which in that case you were destined for failure.