M272 serpentine belt came off

[SeanR]

Hello, wondering if someone can help.

To cut a long story short I was spraying a bit of silicon spray on the belt, think I caught it with the straw and to my surprise, the belt came off

After a bit of stressing, went on you tube and managed to find the 17mm tensioner and put it back on.

It all lines up and has no squeaks, but looking at the belt on the tensioner it looks to be moving off (see pic)

I read there was an upgrade here, surprised there was no lip.
I'm worried it may come off again, any opinions welcome.

Cheers.

 

[Trickythemerc]

Why did you spray the belt with silicone spray ? Could be the silicone causing the belt to slide or perhaps its gone back on in the opposite rotation.

 

[grober]

The belt ribs/other pulley wheel grooves make that unlikely assuming there's no wear on any of the other pulley bearings

 

[SeanR]

Why did you spray the belt with silicone spray ? Could be the silicone causing the belt to slide or perhaps its gone back on in the opposite rotation.

Hello, belt seemed a little noisy and thought id have a go at improving it, me being pedantic, wish I hadn't.

You may be correct, il take another look at it tomorrow and give it a wipe down just in case.

Cheers.

 

[SeanR]

The belt ribs/other pulley wheel grooves make that unlikely assuming there's no wear on any of the other pulley bearings

Cheers, all looks good, thankyou

 

[Trickythemerc]

The belt ribs/other pulley wheel grooves make that unlikely assuming there's no wear on any of the other pulley bearings

The idler pulleys have no grooves and run on the flat side of the belt

 

[grober]

Perhaps I should have called the idler pulley the guide pulley which is ribbed. The 2 pulleys the belt "flat side" runs on are the water pump and tensioner. In general if the ribbed pulleys run true they exert sufficient alignment force to keep the belt in position. If any of the pulley bearing are worn then that might cause them to wobble to throw the belt- the one often the culprit is the small guide pulley between the power steering pump and alternator- which often goes noisy if the bearing is faulty.

 

[MancMike]

Are you sure it's tight enough? The tension should stop it being able to move.

I have this engine and mine sits perfectly on that smooth pulley.

 

[Iceviolet]

Check that the washer on the ribbed guide pulley is on the correct side, i.e not spacing it away from the engine.
Also for future reference it is not a good idea to spray lubricant onto a FRICTION drive belt! Kind of defeats the principle!! He he!

 

[SeanR]

Thanks for the replies gents, I wont be doing it again Iceviolet

I checked to make sure I put it back on correctly this afternoon, went off the youtube video with diagram below.

Its a recent belt, fitted by the previous owner a few months ago. The only tensioner I know about is the tensioner with the 17mm socket, if there is another then I suppose the previous owner may have left it loose, strange coming off the way it did. As mentioned though, don't think ive done myself any favours with the silicon spray :fail

I can move the belt back on the tensioner, drive for a while and when I check it moves forward again, done this twice today.

I will spend more time messing tomorrow to see if I can sort it.

Appreciate everyone's replies, thank you

 

[SeanR]

Hello, just to finish off the story of the slipping belt.

Been bugging me for a short while so bought a new gates belt tensioner from ebay, only £40 delivered. Fitted it yesterday, belt as sat where it should do ever since.

I did notice movement in the old one, and there was wear around the edges of the vinyl wheel.

Anyways, job done

 

[Iceviolet]

Good news. I fitted a gates tensioner to my m273 engine. I usually fit only genuine parts but I think it was nearly 3 times the price. I was pleased to see that the original was truly identical to the gates one apart from the Mercedes part number and logo were machined off!

 

[optimusprime]

Belt look as if its not on the grooved pully far enough .You wont move it over once its in the groves Rake it off and put the belt over to the end of the groove

 

[SeanR]

Hello Optimusprime, might be the photo, its definitely on the pulley ok.

Its staying put where it should do, but now I have another concern

Watching the NEW tensioner when its idling, I see a very small movement, as though its bouncing slightly, I'm not sure whether this is normal or not?.