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Discussion Starter #1 (Edited)
I will be replacing the tensioner in my M5 with the S50B32 unit and was wondering if it is possible to do it wrong, or if the tensioner disengaged from the rail you can't tighten the "socket" fully.

Also how does it retract back into the housing? The thing I don't understand is how you can hold the tensioner while screwing in the socket. Also which way does the little hole go in the tensioner itself (up or down).
 

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http://bmwe34m5.com/node/224

Buy the part.
The workings of it when installing will become clear.
Follow the instructions.
Make sure you have 17mm socket, 30mm & 32mm deep draw socket.

I would suggest removiing thermostat housing cover as per article.
If you don't, you may find consequences are two fold.

Both involve either damaging the thermostat housing or front timing cover when releasing the
original tensioner or not getting the correct torque on the new part when fitted.
Feel & visibility of removed & installed parts is 100% better with cover removed also.

I would suggest that if you have any doubts over your mechanical abilities,
please give the job to someone skilled & willing to take responsibility.
I know many of you are skilled enthusiasts.:applause:
This is a critical part.
Get it wrong & the damage to valve train will require top end rebuild at minimum.

Farrell
 

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Discussion Starter #3
I read the article and have the part. I need to have a look under the hood again. I just did the waterpump before winter storage and hate to have drain the coolant again, but we'll see how it goes.

From the article I gather that if the tensioner is not seated correctly on the rail you won't be able to screw the socket it fully, so I guess you can't really do it wrong.
 

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I will be replacing the tensioner in my M5 with the S50B32 unit and was wondering if it is possible to do it wrong, or if the tensioner disengaged from the rail you can't tighten the "socket" fully.

Also how does it retract back into the housing? The thing I don't understand is how you can hold the tensioner while screwing in the socket. Also which way does the little hole go in the tensioner itself (up or down).
i just did mine the past sunday (have yet to start the car, waiting on a couple of coolant hoses, so you never know!).

The 'insert' of the tensioner, the part that actually contacts the chain guide, gets slipped into the block first, you can twist it as you're putting it in, and feel it engage. It's slightly tricky, but you hold that in place as you put the outer part of the tensioner (the 32mm part) on. Though the web page on bmwe34m5.com suggests filling the outer portion of the tensioner with oil, in my case, when i tried that (on the workbench) the oil just leaked out of the oil feed hole, and made a mess. So i installed it 'dry' so to speak.

Theoretically, if the 'fingers' of the tensioner were not in mesh with the guide, you would have an incorrect installation, but in that case, the 32mm outer part would not bolt on correctly.
 

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Its entirely possible to fit one wrong.:sad1:
Especially if you attempt without removing thermostat housing.
I have seen the results of someone whose ham fisted short cut attempt to
fit this part cost him dear.

Half filling the tensioner housing with oil floats the engagement shaft enough
to allow vertical install & direct engagement into guide rail..usually;)

Farrell
 

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Its entirely possible to fit one wrong.:sad1:
Especially if you attempt without removing thermostat housing.
I have seen the results of someone whose ham fisted short cut attempt to
fit this part cost him dear.

Half filling the tensioner housing with oil floats the engagement shaft enough
to allow vertical install & direct engagement into guide rail..usually;)

Farrell
Farrell, just to clarify (since i've yet to start my car, thermostat housing is still off.
If you can fully seat the outer portion of the tensioner, and the insert did not slip out of place from engagement, what else can go wrong?
I'd like to make sure i'm not missing anything obvious before everything else is reassembled!

you guys must work faster than me to fill the housing with oil! I just ended up with oil all over my hands and workbench! (was using 20w50, perhaps i should have chilled it first!)
:cheers:
mike
 

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you guys must work faster than me to fill the housing with oil! I just ended up with oil all over my hands and workbench! (was using 20w50, perhaps i should have chilled it first!)
:cheers:
mike
Mike,

I had the same battle, but I filled the tensioner housing close to the engine and thus only spilled some oil over the A/C and airpumps. I couldn't care less as I used the oil as cleaning solvent for removing the old contamination caused by dirt and the leaking S38 tensioners diaphragm.

I heard some reports that the tensioner snaps in place even when misaligned, but noone was able to confirm so I was not preparted to take the risk so I didn't, nor would I advice anyone to do so.
 

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I heard some reports that the tensioner snaps in place even when misaligned, but noone was able to confirm so I was not preparted to take the risk so I didn't, nor would I advice anyone to do so.
if it was misaligned, it would not seat up against the engine block, correct?
 

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Hi Mike
It sounds like you have installed correctly.;)
It should indeed sit hard against the washer to the engine & 70Nm later:)

Got a lot of practice fitting these parts.
But, I never take this job lightly, no matter how many times
I do the job.
So, it should be a fiddly job, even for the competant owner who
may only do the job once.
(It was for me a few years ago iirc)

I am with Raymond on this " snapping into place" of engagement shaft.
I have never encountered this phenomenon.

Farrell
 
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