Mini One D 1.4 auxiliary belt tensioner replacement - MINI Cooper Forum

First Generation MINI One D MINI One Diesel 2003 - 2006

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post #1 of 4 (permalink) Old Jan 5th, 2014, 11:39 PM Thread Starter
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United-Kingdom Mini One D 1.4 auxiliary belt tensioner replacement

Hello, I am new to the forum and I'm here to seek your guidance on my topic in question,

Mini is a May 2005 build and is a 1.4D. The car is a relatives, and as I was servicing it yesterday I noticed that the auxiliary belt tensioner had a lot of play in the bearing and it 'whines' when engine is revved.

Looking at the tensioner and it seems it isn't sprung loaded or self tensioning, there was a white paint mark on the tensioner bracket behind of the outline of the wheel.

My question is: how do I properly slacken R&R the tensioner and set it to the correct tension? And are there any special tools needed?

I'm having trouble searching for this part from the big named motor factors where I am (eurocarparts) and seems the only price I can quote is from BMW at 126 just for this tensioner which in my opinion is expensive.

Any comments much appreciated.


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post #2 of 4 (permalink) Old Jan 6th, 2014, 09:38 AM
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You could use RealOEM - online BMW parts diagrams - to work out the part number you want as that might help a non-Mini place locate it.

This should get you to the parts diagrams for a 5/05 One D: * Online BMW Parts Catalog

And this should get you to the belt tensioner diagram shown below: * BMW R50 One 1.4d Belt Drive Water Pump/Alternator

The tensioner in this diagram lists at 116 (4.25 extra for the bolt!) - you can paste part numbers into this site to get full dealer price with VAT:

Cooper MINI Parts, Inchcape

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post #3 of 4 (permalink) Old Feb 8th, 2014, 10:46 PM
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I'd like to know how to replace the tensioner as well, from the alternator thread I can see replacing the alternator means removing the front bumper, hopefully replacing and retensioning the tensioner doesn't need the bumper off.

Likewise, any special tools required.
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post #4 of 4 (permalink) Old Aug 8th, 2015, 05:32 PM
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I have changed this idler myself on my drive.
It's not complicated - just awkward do to lack of space and shocking when you find out the price of the dealer only replacement. Having said that, BMW were 20 cheaper than Toyota for exactly the same part!!

First thing to do is get a jack and a flat piece of wood and place it under the engine oil sump. Remove the to left engine mounting and then gently jack up the belt end of the engine. Stop if you feel any resistance whatsoever.
Get a long spanner and loosen the 4 bolts holding the water pump pulley on. Don't remove them completely as the belt is still under tension. Use the tension of the belt to hold the pulley while you loosen the bolts.
Once those bolts are loose, remove the top adjustment bolt and slacken the lower mounting bolt on the alternator and push the alternator backwards towards the engine to release tension on the belt.
Note where the adjustable idler is located on the adjustment bracket. Release the centre nut and reset the idler at the top of the slot in the mounting bracket. You can't remove the idler, there isn't enough room!!
Note where the belt runs over each pulley and remove it.
Now remove the 4 water pump pulley bolts and the pulley. (A tip is to hold the bolt head with the spanner on it and rotate the pulley). The pulley needs removing as it blocks removal of the top idler bracket mounting bolt.
Now remove the two bolts holding the mounting bracket to the engine. (My top one was stiff coming out and going back in).

Fit the new idler with the idler at the top of the slot and tighten the two mounting bolts.
Refit the water pump pulley and do the bolts up as tight as possible for now.(spanner, thin fingers and patience required here!!).
Refit the old belt if in good condition or (as I did) fit a new one one same way the old one was removed.
Refit the alternator adjustment bolt finger tight in with the alternator pushed fully back towards the engine.
Loosen the idler pulley centre nut and push the idler down as far as possible to take up the initial slack in the belt and hold it there while the centre nut is tightened.
Near the alternator adjustment nut is a square 1/2" hole for a breaker bar/ratchet to provide leverage to tighten the belt properly.
Once the alternator is in the right position, tighten the adjustment bolt.
Now tighten the 4 water pump pulley bolts.
Refit the engine mount once the jack has been lowered enough to facilitate this. Don't let the jack go fully as the engine will just drop on that sideof the car.
Start the car to listen to lack of noise!!!

Last edited by brigbeale; Aug 8th, 2015 at 05:40 PM. Reason: Typing error
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