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Discussion Starter #1
Hi all
Recently bought a mk5 Astra Sri 2.0 turbo. It was advertised as needing new piston rings - the guy said he thought it was just the head gasket but after replacing that it was still not running right and he said he got a compression test and cylinder 3 was low.
The car did actually drive still - it made it the 30-40 minute drive back from collecting it without overheating, it just took a while to start initially and was a bit hesitant in low revs.
It was cheap and I've not replaced piston rings before so thought it would be an interesting winter project :)
So I’ve removed the head and poured some oil in the cylinders to check the seal (saw online this is how to do this) but none of them have lost any - is this a definitive test to see if the rings have gone?
I'm now kicking myself that I didn't do my own compression test before removing the head, as I'm not sure about replacing the rings if I don't have to..

Any advice on next steps?

I think my two options are:
  • stick to the original plan - replace the piston rings, put the new gasket set on and see what happens
  • OR essentially go back to square one - stick the old gasket/head bolts back in (supposedly only a few weeks old) and get a compression test done
Any thoughts/help much appreciated!
 

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If you’ve gone this far, no point in just putting it back together without fully checking everything. Have you removed the whole engine or just taken off the head in place?
I’d be removing the pistons at least and checking for any cracks in between the rings or bent rods (trust me on that one, i own a corsa vxr had had both a piston crack and a bent rod on another piston and it still ran and drove with both!!!)
If that is fine then check the valve seats and the valves themselves. Did the car have any signs of burning oil or water loss or overheating?
If all of the above check out ok, then rebuild, id use a new gasket and head bolts (incase they are stretch bolts) and be sure that it’s timed up correctly
 

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Discussion Starter #3
Cheers for the reply - I've just taken the head off in place and there was no overheating or water loss or burning oil on the drive back, which included motorway driving for about half hour.. it pulled quite well as soon as the revs got a bit higher.
The engine has been modified, bigger intercooler, different cams and remapped - it came with a dyno print out of 275bhp..
I'll take the pistons out and have a look then
 
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