Allowed piston ring gap?

[Avantus]

Hello,

Short question to which I couldn't really find the answer.

What should the piston ring gap be on my RS2? It was measured at 0.70 to max 0.75mm... is that still ok?

thanks!

[UrS4boy]

Hello, Short question to which I couldn't really find the answer. What should the piston ring gap be on my RS2? It was measured at 0.70 to max 0.75mm... is that still ok? thanks!

Check out this pdf: http://s2-audi.co.uk/workshop/aan/aan.pdf

Go to page 36/93 and look at the figure in section 13-35

Gap New = 0.15 to 0.35 mm
Wear Limit = 1.0 mm

So you are still in the game (barely)

[caterpillar]

too tight= wrecked engine......!!!!!

[Avantus]

Ok thanks!

Would you guys advise to replace them? The concern of my mechanic is that the shiny spots on the cylinderwalls might cause the new rings to not run in properly. On all 5 you can see this. Nothing to worry about, or...?

As for the rest he thinks the cylinders still look very good, just those shiny spots are a bit weird. Pistons are looking perfect.

Opinions?

[Avantus]

Cylinders were measured today, and with 81.04 (81.01 std) as a maximum I think I have nothing to worry about. New ringset with mild honing, and all should be good.

[DJones]

Cylinders were measured today, and with 81.04 (81.01 std) as a maximum I think I have nothing to worry about. New ringset with mild honing, and all should be good.

Hone it fit new rings and run it in on a mineral oil for 1000 miles (changing it at first 100 miles) and you should be fine..

[twenty valve]

Hone it fit new rings and run it in on a mineral oil for 1000 miles (changing it at first 100 miles) and you should be fine..

Definately hone it. I wouldn't think about putting new rings into those bores.

Problem is you won't know what the gaps will be after a hone.

You could look into getting liners fitted so you can re-machine bores back to original size.

Either that or get the block re-bored and fit a set of +0.50 pistons

[Avantus]

Since the walls are in very good condition, a mild hone would be enough according to my mechanic.

The piston rings were from goetze, and the revision company instantly said the same as my mechanic, not to be used again (were only 20.000km in!). But since the pistons are looking perfect, and the bore is pretty much standard (0.02-0.03 over 81.01), boring it out wouldn't be necessary. With new rings my ring gap should also be back to how it should be.

And to be honest, saving 1000 euro on this overhaul is pretty welcome (although I do want it done good!)

Thanks alot for the input all!

[twenty valve]

re-bore and new oversize pistons will be alot more than 1000 euros so if your on a tight budget probably best just to wing it

[Avantus]

re-bore and new oversize pistons will be alot more than 1000 euros so if your on a tight budget probably best just to wing it

Oversize pistons are to be bought for a good 800€, which is about 200 left for the re-bore

No seriously, I'm not a "tight budget", but if it isn't necessary ...

[DJones]

Since the walls are in very good condition, a mild hone would be enough according to my mechanic.

I agree, dont use oversize rings, just hone it and use the standard rings to match the standard bore and you will be fine...

[Avantus]

Piston ring gap with the new rings was measured this evening... 0.35-0.40!

Rebuilding it tonight.

[max_s2]

The piston rings were from goetze, and the revision company instantly said the same as my mechanic, not to be used again (were only 20.000km in!).

What rings did you put in in the end? So the Goetze rings were bad and not sugested to put in our engines?

[Avantus]

There came in 5 new original 1st oversize Mahle pistons with rings on them, so no idea what brand it .

[A80Avant]

I think they should be goetze from mahle as well.
Had similar issue with the cylinders being too worn. From 81.26 they had gone to 81.34+ without a hone, so I had to bore and go 2nd step oversize.

Mahle original pistons one have a 0.03mm ring gap size. 2nd step oversize are 81.48 and bores need to be 81.51

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