Rebored Engine burning Oil

[Minornut59]

I'm pretty confident the rings were installed the correct way around. I took my time, as i always do, with this sort of thing and followed the instruction sheet supplied.

I gave the pistons to the engineer for him to check the ring grooves and general condition of the pistons. If there had been excessive wear he would have picked that up i'd have thought. They looked OK to me.

To recap; spark plugs showing normal mixture and not oily;
Excellent compressions uniform across all four cylinders
Breathers clear.

Got to be the oil rings..

I'm going to give it some more time to bed in then if it doesn't its coming aaprt.

[bmcecosse]

Hang on - now you are saying it HASN'T been rebored????

[charlie_morris_minor]

i think you have miss read the post roy..

Have to say i will hone the bores with an engine if i re-ring it and it hasn't been rebored

[Minornut59]

No, of course not. THIS engine has been rebored.

What i said was that with many of the other engines ive built over the years, if the bores have been fine and i've just re-ringed them then i honed those but any o had rebored i didn't bother with the honing.

Hope thats clear

[bmcecosse]

As mud....

[Minornut59]

NOT a very helpful comment BMC!!

[bmcecosse]

A very confusing thread - I'll not comment on it anymore. I've tried to advise - you are determined to ignore. You're on my 'naughty step' now -which means I won't see your posts. G'bye!

[kennatt]

Oh dear the world as we know it has now ended the post is pretty clear to me, perhaps the S N P vote has got to him.. I think I would be looking at the valve stems as well,you would expect to find a plug being oiled with that amount of oil in the exaught. but you say they are all clear. strange, be interesting to know the outcome,which I'm sure you will find. Good luck and watch you don't slip off that step

[katy]

Were the rings .020" oversize as well as the rebore and pistons?

[philthehill]

As an aside
If you have good pistons with grooves for 4 rings - that is for three compression and one oil control rings and you are only able to get piston ring sets for three grooves - that is two compression and one oil control ring. There is no requirement to have the 3 compression rings fitted - the bottom compression groove can be left empty.
So long as the ring grooves are not worn there will be no discernible effect on compression.
You will end up with the same scenario as having fitted 3 groove pistons and the bonus of having saved some money and effort at the same time.
Simples

[Minornut59]

Hi there and thanks for the helpful comments. bit surprised and dismayed at the latest from BMC there but i guess it takes all sorts.

Far from ignoring anyone i was very glad of the advice actually so its a shame we can't all be polite.

Anyway, i decided after reading all the various posts, to pull the engine out and strip it and i found oil sitting in all four pots as expected and the new rings had started to eat into and mark the bores so not happy about that. I honed the bores, which got all but a shadow mark out, then fitted brand new Nural pistons and rings.

After rebuilding and covering 80 miles i am very pleased to report that not a DROP of oil has been burnt. I refilled with a 50/50 mix of running in oil, (what i had left, ) and 20W50 and its running fine. Going to change the oil and filter again in 1000 miles but so far the oil is still clean.

Hopefully i got away with it but i'll be having words with my engineering shop......

Thanks all...