8 replies to this topic

[L1979]

Hi

I've just stripped my engine and found that my crankshaft have big scrape marks on it

take a look at the picture on attachments

Should I buy a new one or is this still usable?

cheers!

One unhappy mini owner

Attached Files

•  DSC_1463.JPG   3.12MB   57 downloads

Edited by L1979, 06 February 2010 - 04:52 PM.

[Cooperman]

The photo doesn't show the condition of the bearing journal very clearly.
However, it depends on whether the crankshaft has been re-ground several times before and is at bottom limit.
Take a look at the big-end and main bearing shells. On the back of each shell it will be stamped with the part number and either 'std' if it's original, +0.010, +0.020, etc. If it's no more than +0.030 you just have to get the crankshaft to a good machine shop and have it re-ground to the next size down. i.e., if it's 0.020" you take it to 0.030". That applies to both main and big end journals. Then you just order up the new bearings at the correct size and away you go. It's a normal and straightforward procedure. By the way, you also need to check the end-float of the crankshaft and get a new set of thrust bearings. If after fitting the standard ones the end float is more than 0.005" you need to fit a set of +0.03" thrust bearings to one side of the centre main bearing. If more than 0.008", fit a new set of +0.003" both sides. In fat, as they are so inexpensive, it's wise to buy a standard set and a +0.003" set when buying the main and big-end shells, then you won't have to add to the order later.
Good luck with this.

[Guess-Works.com]

I make the assumption your talking about the 'scrapes' on the webs and not the journals...

This is normal and a product of the crank being machined and balanced when fitted at the factory.

Edited by Guess-Works.com, 07 February 2010 - 07:50 AM.

[bmcecosse]

But the journal shown is worn too - so either get an exchange crank from one of the usual suppliers - or have that one reground as above. You should also fit a NEW oil pump when rebuilding the engine.

[Ivor Badger]

Is that a flake of white metal sticking to the bottom of the journal?

[bmcecosse]

Looks like it Ivor!

[Dan]

Well something's worn a big groove right around the journal, the bearing shell falling apart could do that. To me it looks like it's scrap but you need to take it to an engineer and get it measured.

[bmcecosse]

I think it's just the normal wear groove - from the bearing shell oil groove. I would expect it to regrind ok - but - I would clean out all the oil ways in the block (and the crank) very carefully!

[Dan]

You might well be right, although it looks very deep and not an even depth all round to me. It also doesn't look very central. Just looks dodgy but then it is hard to tell this kind of detail from a photo.