Morris Minor Owners Club

My engine was sounding a bit 'main bearing-y' so I thought I'd pop it out and have a look.

What I found was the centre main bottom shell was through to the copper, but all the other bearings, both main and big end were looking OK.
I did them all because why not, but I did realise that I could have simply left the engine in, just dropped the sump, and swapped out that easily accessible bearing shell without disturbing anything else.
As it was, I put in fresh shims, tappets, a new duplex timing chain, new hoses and a belt, and painted things a bit.
It's 'running in' on some 'high mileage full synth 10W-40 with lashings of ZDDP at the moment.
Tomorrow, if my back allows, it's brake time!

It was the revelation that just one shell would have been enough to resolve the problem that prompted me to post. If anyone else has 'mains' noise, don't assume you HAVE to pull the engine and lift the crank out. Have a peek at the centre bearing first. If it is patchy, through to the copper in the middle but not generally torn up, it alone may well be the only thing required. It is after all, where the most flex loading occurs on a three bearing crank.

Sounds like you're a pretty capable chap and so doing the other stuff will make the time and money you spent worthwhile.

The trouble is, when you change all the other stuff at the same time, you probably wonder if the main bearing was really the culprit in the first place.

Good that you have it sorted and good advice for those wanting to inspect only the crankshaft.

rocco wrote: ↑Thu Jun 13, 2024 7:56 am Sounds like you're a pretty capable chap and so doing the other stuff will make the time and money you spent worthwhile.

The trouble is, when you change all the other stuff at the same time, you probably wonder if the main bearing was really the culprit in the first place.

Good that you have it sorted and good advice for those wanting to inspect only the crankshaft.

It's the first full engine I've done since I rebuilt a Triumph twin in '78! I've done two or three big end shell swaps with the engine in situ on Vauxhalls, Vivas and Chevettes and a couple of engine swaps again on Vauxhalls but this was quite a nerve wracking task!
I wasn't 100% convinced I had the valve timing right, especially as I inadvertantly left the distributor rotor out initially. On the plus side it spun over building oil pressure for a while before I twigged!
Remarkably, it seems to be fine and there are no leaks. I even overtook something today!

The two bearings to check are number 1 big end, which is the last point in the oil circuit to build pressure, so the first to show wear... and that centre main.