Superceded 3.6 pistons

[Don Settergren]

Who knows what the difference is between the 96410391518 and the superceded 96410391522 piston\cylinder assembly? I think I need to replace one cylinder on my stock '93 C2, and found the older '18 for cheap, yet my car probably has the newer '22 model (disassembly scheduled in 2 weeks). Can they be interchanged? Can they be run together on the same engine?

THANKS!

[BURN-BROS]

These cheap ones might be the ones prone to cylinder head leaks. My advise is to run the cylinders that supercede if this is the case. You must determine if your 3.6 has had the upgrade done already.

[Henry Schmidt]

I am not familiar with part #s but I think we have a great late model piston and cylinder in stock. The cylinders are not interchangeable and the pistons are slightly different also. Call when you have your engine apart.
Good luck

[Don Settergren]

These aren't 'cheap' immitations, but rather, a new Porsche part that is selling far lower than the $560 dealer price. My concern is that the older '18 is not a good as the newer '22. But maybe my '93 C2 built in 3/93 has the '18s from the factory and would be perfectly usable. I need to stop procrastinating and get that engine out to see what I have...

[ChrisBennet]

This is probably stating the obvious but make sure you get the same height group (5 or 6) as the ones you have.
-Chris

[Don Settergren]

I compared pictures of the '18 and the '22. The '22 has an indentation for the head to cylinder gasket that the '18 does not. I'm still not sure if that is the only difference, or if I could use these cheaper '18 cylinders and machine in the groove.

[ChrisBennet]

I thought the cylinder update happened in '92.

What was the damage? If just the cylinder was scratched you might be able to get it replated.

The later cylinders had a wider sealing surface to accomodate the groove. You can't just add the new style groove to the old style cylinders.

I'm not sure if this holds true for the later heads but when an early head is updated to use the newer cylinders, the sealing surface is widened to just fit over the cylinder. This would keep the head from moving side relative to the cylinder. If an earlier cylinder was used with an update head only the "miracle of friction" would keep the head from moving.

Pardon the crudeness of the attempt but I've attempted to make a drawing of the problem. The top picture is the new style P&C and head. The bottom picture is an updated head on an old style cylinder. You can see due to the narrower O.D. of the old cylinder, it isn't held in place side to side by the newer head. You can also see that the old style cylinder has insufficient area at the top to just add the new style groove.




-Chris

[Don Settergren]

Wow, you call them crude, I call them perfect. Your drawings look very much like the pictures I saw of the two different cylinders. I'm not going to purchase the older ones. I;m also going out to buy an engine stand that will hold my porsche yoke and get started pulling that engine. As for the "problem" I think I'll post a picture of the metal chunk I found in my oil after hearing one of those noises nobody ever wants to hear from the back of their 911. Maybe someone can ID before I get to it. It'll be "fun," not that pulling apart a 3.6l engine with 24k on the odometer can be ever called fun...

Thanks for helping me NOT buy the wrong cylinders!