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[JamesV6CDX]

My 2002 Facory LPG 1.6 Astra is losing oil as many know. It's been like it for the last 10k miles and not got any worse.

Symptoms are some blue smoke if you rev it when it's first started in the morning, and, blue smoke after a period of idle, EG sat at lights.

There is NO, repeat NO smoke, under heavy accelleration, or on the over run.

I'd have really thought if it were a ring, it would do it all the time?

There appears evidence of oil on the valve stems / seats when you look through the inlet manifold ports - even though 10,000 miles ago I changed all the stem seals.

When I did this, I couldn't detect any excess movement in the valve guides, although I'm not an expert with cylinder head internals.

Also - the compression on each cylinder, when you do a test, is way more than it should be - about 18bar+!

Any further thoughts?

I have some genuine GM rings at home, full set - just wanted to gather one last set of thoughts, before I strip it all down again! 

[JamesV6CDX]

Oil loss is 1 litre / 200 miles....

[Dazzler]

If you hold it at about 2500-2800 rpm does it blue smoke??? If not then i would be reluctant to touch the rings and look more closely at the head. IMHO.

[JamesV6CDX]

If you hold it at about 2500-2800 rpm does it blue smoke??? If not then i would be reluctant to touch the rings and look more closely at the head. IMHO.

If you hold it at around a steady 3k or 4k there is absolutely no smoke visible - only after a period of idle.

Thing is - for the compression on all pots to be that high, would imply that unwanted oil is getting into every single cylinder?  :-/

[Dazzler]

But oil coming in only after long idle or night stop points at the head and not the rings.

[JamesV6CDX]

But oil coming in only after long idle or night stop points at the head and not the rings.

I agree - it's just odd that after removing the head and changing all the seals, it's still doing it.

What else could be wrong with the head, to cause this? Cracked head?

[Dazzler]

Did you have the head crack and pressure tested??

Is it the same now as it was before you did the head job??

[JamesV6CDX]

Did you have the head crack and pressure tested??

Is it the same now as it was before you did the head job??

Yep, after a head rebuild and new HG, it's no better at all.

Shamefully no, I didn't have the head tested - because after looking at it, I was so convinced it was the stem seals (especially as the original ones were the crappy troublesome red ones...)

[Dazzler]

Did you have the head crack and pressure tested??

Is it the same now as it was before you did the head job??

Yep, after a head rebuild and new HG, it's no better at all.

Shamefully no, I didn't have the head tested - because after looking at it, I was so convinced it was the stem seals (especially as the original ones were the crappy troublesome red ones...)

Mmmmmmm Vx alloy head not being tested :-?.
Not something i would do.

Wait and see if any other ideas come along James, but i would rip its head off again and have it tested.
IF all is well then your half there to doing the rings

[JamesV6CDX]

Mmmmmmm Vx alloy head not being tested :-?.
Not something i would do.

I've never seen one fail before, and have changed a fair few... 

[Dazzler]

Mmmmmmm Vx alloy head not being tested :-?.
Not something i would do.

I've never seen one fail before, and have changed a fair few... 

Ive had a few needing skimming due to warping and only about 3 that were cracked.

MarkDTM will probably be the man for this one maybe.
Its ony my view your getting at the moment James.

[JamesV6CDX]

Your thoughts are appreciated mate 

[iainb]

James,
My mig is doing something very simular.     burning oil when stuck in traffic or left to idle for long period's.
But it passed the MOT less than a month ago with a clean bill of health
whats of intrests is I asked them to check for oil burning at idle and was told that it wasnt ?
My oil consumption is about 1L per 1000 miles but I can see the smoke when I pull away in traffic.
I am tempted to do a flush using diesel fuel, only about a litre when the warning of low oil comes on the screen and see if the deglaze fixes the problem.
I will let you know my result.

[Dazzler]

Your thoughts are appreciated mate 

Always a pleasure

[Gaffers]

Had similar symptoms on a veccy 4 pot.  Turned out to a valve stem oil seal with a hole in it.  Compression test will confirm piston rings if it doesnt then its head off I'm afraid