e34 525i v belt tensioner replacement - BMW Forum

Daren525i · 01-23-2010, 01:56 PM

I was hoping that someone could help me with diagrams of how to replace the tensioner for the alternator/water pump v belt. On my way to work yesterday it fell apart and I have ordered the new part but I am not sure what it should look like correctly installed, it is hydrolic. Also it would be helpful if anyone had a digram of the correct belt path.

Thanks a million in advance!

witeshark · 01-23-2010, 02:03 PM

Have you tried realoem.com ?

marti5 · 01-23-2010, 02:18 PM

Hydraulic tensioner?, Ive never seen one on a BM...sprung loaded maybe??

Daren525i · 01-23-2010, 02:30 PM

I have checked realoem.com, I downloaded the instructions but what they say I should see and what I actually see don't match up. the tensioner is spring loaded but when I ordered it from Imported auto parts, their computer system calls it hydrolic, it did confuse me because there are no hydrolics involved. the pic they showed me looked right but I'll see on monday I suppose

marti5 · 01-23-2010, 03:02 PM

Its spring loaded.....

bherde · 03-13-2010, 09:06 AM

Depending on the manufactur date. If it looks like a round actuator, it is a spring, If it has what looks like a piston, it is a spring loaded hydraulic damped device. and they wear out after a few hundred thousand miles. You will not know it is worn out till you change the belt. The tensioner will over extend and only if you are very lucky will it pop back in and allow you to compress it far enough to put the belt back on. Too much force will bugger up the allen bolt you are using to move the tension pulley back. If it does pop back, it will continue to do it's job till the next belt.

Pete Lech · 10-08-2012, 04:43 PM

Just ran across this thread, and want to point out that on my car,the belt tensioner bolts are TORX, not allen bolts. Just close enough to make it easy to screw up the bolt.

You will have to remove the fan/clutch assembly to be able to get to the main belt tensioner bolt. Here is the best link I have found on how to make a tool to remove the fan bolts and save buying a $70 tool for a one time use. Worked great for me.

How to Replace Hydraulic Fan Clutch of BMW E34 M50, DIY BMW E34 by Assoc. prof. Boonchat Netisak