10 replies to this topic

[Iain L]

Hello all. Im going to be rebuilding my 998 soon as its getting a little tired now and with 107k on her most of the gaskets an seals on engine are leaking oil everywhere!

My question is how do you know if the crank will need a re-grind?

The engine still runs well, apart from burning a bit of oil and slight blue smoke bottom end is, or seems very healthy. So will it just be a case of new shells, bearings etc or will you only be able to tell when engine is stripped?

Thanks Iain

[Wil_h]

You need to measure the journals and see how they compare the the specified limits in the haynes. If they are too small then you'll need a grind.

[Iain L]

You need to measure the journals and see how they compare the the specified limits in the haynes. If they are too small then you'll need a grind.

Ok thanks, measure it with some vernier calipers??

[Wil_h]

Yep that's what I use.

[Ethel]

What state are the shell bearings in?

[Iain L]

What state are the shell bearings in?

No idea as of yet, engine is still in car, im just trying to work out what will need to be done.

As said above, bottom end seems very healthy so im not expecting to find many problems when i strip it but i suppose you never know...

[Ethel]

I'd go by the condition of the shells - it's hard to wear a steel crank without chewing up the tin bearings as well. Measuring accurately with verniers is nigh on impossible, even if the journal is the right thickness between the caliper jaws it doesn't mean it's true & concentric with the rest.

[TopCatCustom]

You need to use a micrometer for an accurate reading. If verniers were good enough then machine shops would use them as so much quicker!

[MRA]

Verniers have the nickname of very-nears

You will need to measure the journals for ovality, barrelling, tapering ...... not to mention the surface finish, we use a surtronic surface gauge for the last one.

[Iain L]

Sounds like it would be best to get a regrind then, being as there not too expensive and ive not got any of the measuring tools etc.

Thanks for info

[Big_Adam]

I just gave mine to my machine guy, £10 to check its straight and everything was in spec.