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Head is off - bore maintenance?

Posted: Thu Mar 09, 2023 7:52 am
by don58van
Hi engine experts -- a question for you.
I have the head off to rectify a head gasket failure (water leaking into a cylinder).
Before putting it back on, I am wondering if there is any maintenance I can do on the bores. I don't want to drop the sump.
The bores look to be in good condition and there doesn't seem to be a significant lip at the bore tops.
What I am hinting at is - is it practical/worthwhile to do a bit of deglazing or whatever without removing the pistons or should I leave the bores alone. Yes, I know that it would not be ideal to do any maintenance on the bores without dropping the pistons out. I have been closely following this and other Minor messageboards for well over a decade and I can't recall this ever being discussed (maybe because it is a silly idea :roll: ).
Don

Re: Head is off - bore maintenance?

Posted: Thu Mar 09, 2023 8:08 am
by rocco
Not an engine expert but if you think there is a enough carbon build-up to warrant you to consider cleaning it up, my advice would be to do it properly/fully otherwise leave it alone and make it a job for another day.

Re: Head is off - bore maintenance?

Posted: Thu Mar 09, 2023 8:09 am
by svenedin
I’ll be interested to hear the responses to your question as I will probably be doing the head gasket in the not too distant future. I don’t want to hijack your thread but I’d also like to know what might be advisable in terms of head maintenance that can only be done with the opportunity of the head off.

Re: Head is off - bore maintenance?

Posted: Thu Mar 09, 2023 8:30 am
by don58van
Thanks for your prompt replies.
I have a feeling that deglazing is only done when new rings are being fitted, but I will wait for the experts to comment.
Don

Re: Head is off - bore maintenance?

Posted: Thu Mar 09, 2023 8:58 am
by philthehill
Unless you are prepared to remove the sump I would leave well alone.
De-glazing the bores can be done at any time not just for new rings but it does require the pistons & con rods to be removed and the bores to be meticulously cleaned afterwards.
Clean the carbon off the centre of the piston but leave the carbon around the edge of the piston. Leaving the carbon helps keep the seal around the piston.
Whilst the head is off give the valve seats/valves a light grind.

Re: Head is off - bore maintenance?

Posted: Fri Mar 10, 2023 6:15 am
by don58van
Thanks Phil
I'll just finish preparing the head and give the pistons a Minor :D clean.
Don