Aux belt came off..

[Agour]

You're right, it's just the one bolt. It's a t50 bolt and impossible to get off (it's on very tight).

Is there a special tool that will give me enough swing to get it off?

The only 3/8" socket and wrench I can fit in is too short to get enough leverage on the bolt..

[bobins]

Coincidentally, I've just been researching the correct aux belt tensioner for my C5. There appear to be 2 extremely similar tensioners available for the DW10BTED4 engine, but their dimensions differ very slightly. Dayco list two tensioners - APV1114 and APV1028 and both will fit the C5, it's the same with Gates - T38237 & T38477, but they're not quite the same size. Confusingly, Febi and others list their tensioner as being compatible with both sizes.

[Agour]

Perhaps that's what's causing my issue then! Managed to finally get it all on after a lot of struggling.

Brand new skf belt and dayco tensioner.

Same issue as before.. The belt is overhanging the tensioner by a few mm at the bottom.

I checked the tensioners side by side before refitting and they were the same size.

Does it say which dimension is different on those tensioners? If its the width of the roller, that could be what's causing my issue.

Either that, or the entire bracket that holds the tensioner on is misaligned.

[bobins]

As far as I can see, the 67.7 & 55.5 refer to the depth of the whole unit i.e. from rear mounting face to the tip of the roller fixing bolt. The Gates equivalent has the roller width as 25.0 on one and 25.6 on the other. Unhelpfully, one of the Gates ones has the overall width as 73mm, which doesn't tie in with anything

Dayco tensioner 1 - Dayco, fair use

Dayco tensioner 2 - Dayco, fair use

[bobins]

More confusion......

The applications list for the Gates belt shows a crossover with some of the C5 variants.

Gates tensioner - Gates, fair use

Gates tensioner 2 - Gates, fair use

[Agour]

Damn.. Proving to be a bit of a nightmare then! The tensioner would easily be wide enough for the belt if it was straight.. So my gut is saying that something is misaligned in my engine.

If this was a common issue with tensioners being wrong, I'm sure it would have been heard about a lot before

[Agour]

For what it's worth, I checked and the new tensioner is an apv1114

[Steve Walsh]

Could be worth checking the alternator clutch pulley, I had one fail and it destroyed the belt

[Agour]

Good idea.. how do I check it?

I span it by hand and it seemed to move freely with no bearing issues

[Steve Walsh]

https://www.gatestechzone.com/en/proble ... tion-tests

A bit of interesting reading for you,
When mine failed there was no warning.

Steve