2nd Gen R56 Cooper S Most liked posts in thread: Timing Chain Tensioner & Engine Oil

Yes, the tensioner can leak externally - if it loosens up. They had a rash of these in 2010....some have described it as looking like a bolt - it's like that in that it has a big hex head and it threads into the cylinder head with a copper washer, much like the oil pan drain plug.

The way to check it is simply put a big ass wrench on it and see if it's loose.

BTW, I'm speaking of an R56....

 

1.+2. Only if the valve cover gasket is leaking.

MINI usually describes this condition the other way around. Low oil level(they say) causes the tensioner/oiler to run dry and malfunction. However, the R56 07-09 had poorly designed tensioner oilers that malfunctioned and have been replaced with a better design(we hope). I hope that this helps.

Jason

 

Had a Mini SA tell me that after sitting unused for a couple weeks, oil "bleeds" out of the tensioner (internally, not externally) and when the engine is started again, take it easy "for awhile" while oil builds up pressure in the tensioner again.

He told me this while I was waiting for my chain / tensioner to be replaced. New tensioners aren't supposed to have this problem.

 

The tensioner is a hydraulic cylinder, and is pressurized to apply tension and keep the chain taut. When the engine is not running --- no oil pressure applied. The original tensioner apparently has a faulty seal, allowing the pressure to bleed off --- internally, not an external, visible leak.

 

A leaky tensioner will drain back into the oil pan. The oil will drain along the same paths that oil from the valve springs, cams, etc, drain.

This is a different problem from a loose tensioner. Loose will cause oil to leak past the mounting threads --- an "external" leak, and very visible. A perfectly good tensioner can be loose and cause your oil leak. A loose chain can come from stretching, broken guides, or a faulty tensioner.