I've finally got round to removing the head from my Astra GSi.
It's been using oil and smells oily from the exhaust, so I did a compression test.
It measured around 190 PSI on all 4 pots. (That was summer last year).
Anyway, now I've removed the head, I can feel a ridge on all 4 cylinders. It's very slight, but it is there. Otherwise, the bores/pistons etc look perfect. It does emmit slight blue smoke occasionally but strangely only when the oil level is on MAX.
What are my options now? Do I need a rebore or could I get away with something else? I will be fully reconditioning the head.
If you only want standard spec then a rebore would be a good idea as the pistons only cost around £35 each.New rings and honing the bore might work but you`d be a bit p.issed if it still smoked afterwards.
Have ya checked the stem seals on the head....they can cause the engine to smoke as they get hard and brittle with age.Will smoke on the overun if thats the case.
Allo mate - well I shall be stripping the head down this afternoon and I'm sure I'll find knackered stem seals, if not worn valves & guides.
Like you said though - I'll be really annoyed if I do just the above & then it's still not right when it's back together again.
Perhaps I should just bite the bullit and go for a re-bore wi new rings/pistons.
Just out of interest - is it acceptable to have any ridge at the top of the bore or would an engineer automatically re-build it?
> Anyway, now I've removed the head, I can feel a ridge on
> all 4 cylinders.
I thought this was normal, it quotes this in the haynes book when removing the psitons. I got this a bit on my C20LET block. Its where the piston reaches TDC but the rings aren't, theres a small gap so deposits build up here. This is what you can feel. You can remove it with a soft tool like wood or plastic scrapper. A rebore for me £10 (gave engine block to local engineering shop).
Yeah, I thought that too but on the thrust side (i.e. the front & back of the bore when looking at the engine in the car), the ridge is very slightly more pronunced than the non-thrust side. If that makes any sense at all!
The ridge is black coloured - I'll try removing it gently with something.