Engine Drivetrain 1st Gen Cooper S Most liked posts in thread: Tensioner: Why so scored?

:cornut: Those marks are verticle not horizontal. They come from in and out motion and not rotating motion. The male piston a loose fit in the female cylinder causing initial woble until fully lined up by cylinder?

Jason

 

:cornut: Yeah I see that Nathan. But it appears to me that the male piston was grinding(up and down) in the female cylinder. Doesn't the piston travel in and out of the cylinder also?

Jason

 

There's also scuff marks higher up on the cylinder, too. Was the crankshaft balanced when the engine was rebuilt? I'm thinking the tensioner could be not just the cause but a symptom of something else vibrating.

 

If this is the third design made on the tensioner.... It's quite possible the piston is supposed to rotate so you don't get a concentrated wear spot like the 100,000 mile example..

If it's not a deliberate design function, well then......

It still bothers me that they are "crunchy" when new..... That shouldn't be the descriptor for a close tolerance part.....

 

Wow the head was decked & maybe more than once! Wonder why I never mentioned that to you. Guess I'm getting forgetful. :crazy:

Glad you got it working!

 

I love simple low tech solutions. Glad everything is back running nice again Nate.