Nikasil re-ring
 

Howdy, I am currently in the process of having an 87 carerra 3.2 motor rebuilt. It smoked from day one and I got quite sick of this. My question is this: how important is it to have new cylinders and piston installed versus new rings? The motor had 140k on it and two rings were broken. Upon my visual inspection, the cylinders looked okay, but I was told that re-rings never properly seal. Am I being mislead? I would appreciate any help on this.
Thanks
C

Hi:

Seating new rings in used Nikasil cylinders is a bit of a crapshoot; sometimes they do and sometimes, not.

Even after careful cleaning and preparation of the cylinder walls, it can be a challenge to get them seated and I'd recommend using an engine dyno if you can get access to one.

Steve,
Now I'm worried...I reringed my Nikasils, Jerry Woods did the prep. and put the rings on. That was 10k miles ago...car seems to run good but I had low compression when I did a straight compression check. Maybe the engine wasn't hot enough... any way how should I check this again?
I've done some track days and drive daily and it seems to run fine.
Thanks,
-Henry
89 911 3.2 now with 84k miles

Hi Henry:

LOL,..The two best indicators of good ring seating are leakdown tests and oil consumption.

As long as those are OK, I would not worry about it at all.

With the fact that you already had broken rings I suspect your pistons are worn enough that they aren't good candidates for a re ring. If they measured good then re-ringing is an option. I can understand a shop not wanting to guarantee that they would seat though.

-Andy

It sounds to me like it might be more hassle than it is worth. Although I might save three grand if they work, that money could be lost if the rering doesn't and they have to remove the motor again. Any ideas of what to do with the used pistons and cylinders?

thanks
Carl

You did get 140k miles out of the old ones. Don't feel too bad. You can sell the old set on here or e-bay. Someone might try them for a race engine or just the cylinders for a race engine.

-Andy