M57TU Aircon Belt

SirHiss · #1 11-02-2022, 12:35 PM

I recently replaced the water pump, thermostat, viscous coupling, fan, serpentine belt, tensioner, tensioner arm and roller and idler roller on my M57TU diesel engine. However, when I came to fit the tensioner, tensioner arm and roller and belt to the aircon compressor, I realised that it previously did not have them and instead used a stretch belt (slightly shorter). Upon inspection though, it does have the mounting hardware and threaded holes to accept the parts that I had already bought! I was just missing 2 bolts to hold the tensioner on. I looked up the spec on realoem and found that they were M8x22 so I ordered some (I went with cap/allen headed bolts as they are commonly used on this car).

So today I went to fit the parts thinking it was going to be easy as it's only 2 bolts etc. But no. There is absolutely no way to get one of the bolts in! It is so far up and obscured by other things that I couldn't even get it started with my fingers WITHOUT the tensioner in place! With it in place, I couldn't even touch the bolt or get a tool in, in any direction! How is this done?! The even bigger concern is that I couldn't get the thread started. The head of the bolt was touching something else and I think forcing the bolt in at an angle so there was no way it was going anywhere. I just don't understand how I'm meant to do it. Is this why the car didn't come with a tensioner?? I bought a stretch belt too (by accident initially) and I could just put that on there but as I have already spent £60 on the tensioner assembly I wanted to fit it. I also don't have a special tool to fit the stretch belt.

Does anyone with an M57TU diesel have any insight into this or can provide pictures of theirs?

I have added some pictures to help illustrate the problem. The blue circle is a little access hole behind the threaded hole. No idea why this is here as the bolt enters from the other side.

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SirHiss · #2 11-02-2022, 12:39 PM

For some reason I can't edit the original post but wanted to add this...

sgrice · #3 11-02-2022, 01:19 PM

I have replaced the stretch belt on my son's e70 35d which has the M57 engine, but have no experience with the tensioner setup.

Which bolt(s) is it that you're having trouble with exactly? I think it is the 2 bolts that attach the belt tensioner (part 3 in the realoem diagram). I think (but am not certain) that you are trying to attach them after affixing the bracket to the engine. If that is true, then (as I read the instructions) that is the incorrect way to do it. It seems the belt tensioner is put in place and the bolts are started (but not tightened apparently) before attaching the bracket to the engine. Then once the bracket is in place, the tensioning lever is placed and the attachment bolt (looks like part number 8 in the diagram, though it is greyed out and no part number given in the diagram) is threaded in to affix the tensioning lever. Then all the bolts are tightened up. Not sure if you have room to do that or not, but that is way I read it.

Of course, I could be misunderstanding and maybe you tried what I talk about above. In that case, I don't have any other ideas (other than go back to the stretch belt).

Good luck. Let us know what happens.

Stephen

SirHiss · #4 11-02-2022, 01:23 PM

Also, how do I turn over the engine to fit a stretch belt without a stupid special tool?

sgrice · #5 11-02-2022, 01:29 PM

And not sure, but I wonder if the hole you have circled in blue is an access point for inserting a pin to keep the tensioner arm de-tensioned when putting on the belt? Then once the belt is in place, the pin is removed and the tension arm is then allowed to put tension on the belt?

Again, no experience with this setup but the above is my best guess.

SirHiss · #6 11-02-2022, 01:31 PM

Quote:

Originally Posted by sgrice

I have replaced the stretch belt on my son's e70 35d which has the M57 engine, but have no experience with the tensioner setup.

Which bolt(s) is it that you're having trouble with exactly? I think it is the 2 bolts that attach the belt tensioner (part 3 in the realoem diagram). I think (but am not certain) that you are trying to attach them after affixing the bracket to the engine. If that is true, then (as I read the instructions) that is the incorrect way to do it. It seems the belt tensioner is put in place and the bolts are started (but not tightened apparently) before attaching the bracket to the engine. Then once the bracket is in place, the tensioning lever is placed and the attachment bolt (looks like part number 8 in the diagram, though it is greyed out and no part number given in the diagram) is threaded in to affix the tensioning lever. Then all the bolts are tightened up. Not sure if you have room to do that or not, but that is way I read it.

Of course, I could be misunderstanding and maybe you tried what I talk about above. In that case, I don't have any other ideas (other than go back to the stretch belt).

Good luck. Let us know what happens.

Stephen

I'm having trouble with the bolts that hold the tensioner on. #4 in the diagram. The bottom bolt I can get in just fine but the top one the access is impossible and the bolt head may even be being blocked by something. I already replaced the serpentine belt tensioner and yes you do not tighten these #4 bolts down until you push the lever arm in and secure it with bolt #8, otherwise it may not go in (ask me how i know

) but I can't even get to that point with this aircon tensioner.

I may just jack the whole thing in and fit the stretch belt but now I don't know how to even crank the engine!

sgrice · #7 11-02-2022, 01:48 PM

Pardon me if I am misunderstanding (and for repeating myself), but are you trying to put the #4 bolts in before or after attaching the bracket to the engine? I think you are trying to put the bolts in after attaching the bracket to the car, and I think it should be done before attaching the bracket to the car. Forgive me if I'm wrong, but which way are you doing it?

With regard to the stretch belt, the "by the book" approach utilizes a special tool which is pricey. Others, though, have made it work with a combination of techniques. Here is one link with a thorough description, and here is a YouTube video with another option (the video is on 335d but it is of course an M57 engine).

Stephen

SirHiss · #8 11-02-2022, 02:00 PM

Quote:

Originally Posted by sgrice

Pardon me if I am misunderstanding (and for repeating myself), but are you trying to put the #4 bolts in before or after attaching the bracket to the engine? I think you are trying to put the bolts in after attaching the bracket to the car, and I think it should be done before attaching the bracket to the car. Forgive me if I'm wrong, but which way are you doing it?

With regard to the stretch belt, the "by the book" approach utilizes a special tool which is pricey. Others, though, have made it work with a combination of techniques. Here is one link with a thorough description, and here is a YouTube video with another option (the video is on 335d but it is of course an M57 engine).

Stephen

I'm not sure what you mean by bracket. The bolts have to go through the holes on the black thing (tensioner) I pictured sitting on the floor.

sgrice · #9 11-02-2022, 02:35 PM

Sorry - it appears that I didn't clearly understand the various parts that are being discussed. Upon closer analysis I was misunderstanding how the tensioner system works. By "bracket" I meant the piece in the realoem diagram that is not numbered, but is located between parts 3 and 5 in the realoem diagram. I had thought that it was part of the tensioner system, but upon reflection it seems that this piece is already on your engine. It looks like it is held in place with 2 bolts. One bolt is next to the blue circle in your picture, and the other is above it. Not sure if there are any other bolts holding this piece in place? If not, can those bolts be easily removed? Then with the bolts removed the "bracket" comes off, the belt tensioner and tensioner lever put on easily, then the complete assembly put back on the engine.

The above is speculation on my part, but if it's only 2 bolts holding that "bracket" in place then it seems like it should work. If not I'm out of ideas

wpoll · #10 11-02-2022, 02:41 PM

sgrice may be correct - you may need to loosen the compressor mount bracket to get enough access to mount the tensioner.

You'll also need to be creative in terms of getting the pulley and its shaft installed - I had to remove the pulley from the shaft to get enough clearance behind the radiator to get the shaft inserted through the compressor bracket and into the tensioner.

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