1098r Cam Belt - Is This Normal?

No shavings or debris - where do you think they went? You can tell if it's a manufacturing defect - well our lab can at work :smileys:

 

Looks like it has been run over the idler or tensioner pulley belt retainer plates/edges.

 

It could have ridden over it, by turning the engine without the covers on by the person who fitted the belt.

 

Just a thought, but I would pull the covers off and re-inspect that same belt once you've put a couple of hundred miles on it to see if the groove reappears. If so you'll need to delve deeper.

If course of there isn't a groove on the new belt, happy days!

 

Oops, sorry I missed that but in your last post.

Blame it on old age and failing eyesight

 

Having seen the belt I think that however it happened this is the most likely causation. The 'Groove' is far too smooth to be the consequence of abrasion, it's only aprox' 0.5mm deep and is aprox the width of the idler / tensioner pulley retaining rim.
My theory is that whoever fitted the belt originally possibly cocked it up on fitting, possibly didn't have sufficient tension on the belt whist revolving crankshaft by hand, the belt then rode off the pulley and found itself jammed against a pulley's retaining wall resulting in the groove being formed on the belt.
Error realised, the belt was then fitted and tensioned correctly.

 

I would have thought if the belt was fitted over the pulley flange

• When the engine was rotated by hand, the belt would want to work it's way back onto the pulley due to the belt being misaligned.
• The groove is quite a way into the belt, is it even possible to get the belt this far over the pulley without it rubbing on the engine casings?
• Would the cam timing stay in place with the belt like this and rotating the engine by hand? I realize it could have been reset without damage being caused.

 

I'm wondering if during manufacture the belts are held at either end with a guide/drive roller for the slicing process. This could cause this depression while the polymer is still hot. The end bits usually then being discarded, perhaps this one slipped through. The belts are manufactured as a wide strip and then sliced as mentioned earlier by someone. If the belts 'skin' was not broken then this may be a possible cause, but only a guess. The depression would be very difficult to form while in situ in the engine if the 'skin' isn't broken.

 

Good theory, I am inclined to think you might be correct. The belts 'skin' definitely wasn't broken ,and the 'groove' was exactly parallel to the belt's edge along it's entire length.

The only thing against this theory is it just seems so unlikely that who fitted the belt would have done so with the obvious implications of belt failure from a 'Not 100% perfect belt'

 

Happy to come over again sometime soon Richard and we can check the tension again with my equipment.
I would expect to see a reduction in tension after initial setup and the belts settling in.
Something in the region of 80Hz perhaps?

 

Yes, in-service tension is supposed to be quite a bit looser than new fit. Something like 80-90 iirc

 

As you look at the picture of the engine do the cams run anti clockwise as you look at them , in normal use upper run of belt is the tight run and lower run is the tensioner run , and the tensioner is a fixed type ...... No auto tensioning device like most cars have ??