Two chain tensioners...

[hoveringuy]

..both out of M50's. What is the difference between these, which is better (the one on the left weighs about 1lb, the one on the right maybe 3oz!) and are they chain ramp specific or interchangeable.

Sorry, no part numbers on them.

[PiercedE30]

They are chain guide rail specific. there's a split in which one is used, I think around 96/97.

[golde30]

i have the one on the left in my s50. definately something you wanna replace with new part.

[e30serg]

Can you see any part #'s on them? Read this little article. The tensioner got updated at some point. Read this:

http://www.pelicanparts.com/bmw/techarticles/101-Projects-16-Tensioner-Upgrade/101-Projects-16-Tensioner-Upgrade.htm

[hoveringuy]

Sorry, no part numbers. I looked.

I've seen the outside discussions about upgraded tensioners working on older motors even though it is not officially endorsed by BMW.

As far as my two examples, the one on the right came out of an M50 from a 525. I read somewhere that it is different because the oil hole on the top is designed to oil the chain more effectively, maybe the ramp has a hole in it for the oil to pass through?

Dimensionally, they are identical.