Spun Main Bearing again

After recently rebuilding the RR5 motor and replacing all the main bearing shells ( as one had spun) the motor sounds as if it has spun a bearing again. The motor sounded superb after rebuilding and now sounds as if someone is in there tapping a little hammer. Any thoughts on using Loctite 660 on the outside face of the offending shell. Gutted! I have another RR5 motor which has a broken lower crankcase on the alternator side, so have placed an ad in the wanted section for crankcase.

 

Gutted, did you ID the shells? New shells? Did you plastigauge them?

 

Yes Arthur, did all of that can't believe it, all that hard work gutted.

 

Yeah I'd be pissed! Not sure how I would move forward from that for fear of same again!

 

Yeah exactly that, will concentrate on getting the other motor sorted. Either another lower crankcase or repair the broken one, will pull it apart tomorrow.

 

Post up some pics if you can face it! Got to admit I'd turn that motor into a coffee table!

 

Sounds like a plan Arthur, only done 7000 miles. Other motor (original one) is at 20,000 but never had any trouble until a high speed off took away the alternator and chunk of crankcase, looks like it will have to go back in and do some more miles once crankcase is sorted.

 

Good luck mate, I know you must be pissed as I would, lot of work that last motor!

 

Quick update on spun main bearing, spent this evening pulling apart motor 1 ( original motor) with alternator ripped off and damaged crankcase, now have the lower crankcase removed and ready to go up to work and be repaired. Will get some pictures taken before commencing repairs, we repair a lot of engine cases as part of our business but this one will certainly be a challenge.

 

I,m pretty sure that the cases are a matched pair so swapping them about might cause you even more hassle and costs if it spins a shell again. Once a shell has spun its more or less scrap .

 

Not quite sure if my line of thinking is correct but i thought the crankcases are line bored in a production environment therefore the O/D of the shells are constant. The variation occurs on the I/D due to crankshaft grinding fluctuations which necessitate different size shells. Just my thoughts. Not to worry though the original crankcases have been repaired today, i will post up pictures of the repair being carried out by us as soon as possible.

 

How so? Welded/re-bored?

 

In answer to your question el-Nicko, the alternator side of the lower crankcase has been re-fabricated and welded. Very pleased with the finished job. This engine is the original one and not the one with the main bearing problem, we are yet to pull that one apart and have a look.

 

First picture of crankcase repair.

 

Picture 2 showing machined posts in place.

 

Sorry to upload pictures this way.

 

Previous post shows edges having been smoothed ( welded) and machined posts tacked in place.

 

Again another view of posts in place, the larger one in the picture is the one that will be tapped m6 and have the locating dowel machined in.

 

More images

 

This picture shows infill plates having been profiled and fabricated to fill the gaps.