Cam Belt Tensioner Bearing Failure

[Ken]

During a normal service on my ST3 today, I found this cam belt tensioner bearing failure. Note the missing balls on the top of the bearing. Fortunately, the remaining balls remained intact. (click on thumbnail)

Has anyone else experienced this problem? The motor has 43,000 miles.

[ST3S]

The bearing on my '06 ST3s is sealed. Did your bearing ever have a shield? Did you locate any of the pieces?

[Ken]

Originally Posted by ST3S

The bearing on my '06 ST3s is sealed. Did your bearing ever have a shield? Did you locate any of the pieces?

Both bearings are exposed on each belt. I just ordered a pair of bearings from Colorado Euro in Loveland for $16 each. If they are sealed, I will replace both of the outside bearings.

I didn't find any of the balls or other pieces when I removed the stock cam belt cover. I need to look more closely in the morning.

[TheX]

Damn, that's scary. Glad you found it before total failure.

[stryder]

Originally Posted by Ken

Both bearings are exposed on each belt. I just ordered a pair of bearings from Colorado Euro in Loveland for $16 each. If they are sealed, I will replace both of the outside bearings.

I didn't find any of the balls or other pieces when I removed the stock cam belt cover. I need to look more closely in the morning.

All the belt rollers are sealed bearings on my 2005 ST3.

[Ken]

I received the new bearings from Colorado Euro and they are sealed. I found the exterior ring seals from the failed bearings.

I removed the bearings from the tensioner in the photo today and found the rear bearing froozen. The belt on the tensionrer is damaged on the backside since the bearing was no longer freely turning.

It appears to me that both belts were over-tightened by the dealer during the last service. Theres was no play between the bearings and the belt. It appears the over-tightened belts caused excessive heat in the bearing resulting in their failure. The other bearings on the horizontal clyinder still turns freely. However, the balls are exposed as well. So, I replacing all four bearings.

Removing the bearings required the bearing puller. Installing the bearings required a bearing tool setting device.

[stryder]

Originally Posted by Ken

I received the new bearings from Colorado Euro and they are sealed. I found the exterior ring seals from the failed bearings.

I removed the bearings from the tensioner in the photo today and found the rear bearing froozen. The belt on the tensionrer is damaged on the backside since the bearing was no longer freely turning.

It appears to me that both belts were over-tightened by the dealer during the last service. Theres was no play between the bearings and the belt. It appears the over-tightened belts caused excessive heat in the bearing resulting in their failure. The other bearings on the horizontal clyinder still turns freely. However, the balls are exposed as well. So, I replacing all four bearings.

Removing the bearings required the bearing puller. Installing the bearings required a bearing tool setting device.

Did you hear any high pitched bearing whine beforehand? When I tension my belts, by hand, I warm the bike up very well and bring the revs up and down numeous times to see if the pitch changes. Too high a pitch after warm up, the belts are too tight. I agree, the belts may have caused the bearing to seize if they were too tight. And here I thought the bearings were a straight r&r. Thanks for the heads up. If I ever get a little extra money, it would be wise to order a set to have around. Good thing you caught them on time.

[Ken]

Originally Posted by stryder

Did you hear any high pitched bearing whine beforehand? When I tension my belts, by hand, I warm the bike up very well and bring the revs up and down numeous times to see if the pitch changes. Too high a pitch after warm up, the belts are too tight. I agree, the belts may have caused the bearing to seize if they were too tight. And here I thought the bearings were a straight r&r. Thanks for the heads up. If I ever get a little extra money, it would be wise to order a set to have around. Good thing you caught them on time.

At 26,000 miles, my bike off of warranty burned out the $1100 speedo unit. My dealer warrantied the speedo on good faith. So as pay back, I let them do the service at 32,000 miles. The belts were changed then.

I didn't notice any noises out of the ordinary. However, when you throw in the normal motor noise, dry clutch rattle and I normally wear ear plugs, I may not have noticed. Only one of the four bearings were actually frozen. The other three still rotated.

[Gearbox]

Originally Posted by Ken

At 26,000 miles, my bike off of warranty burned out the $1100 speedo unit. My dealer warrantied the speedo on good faith. So as pay back, I let them do the service at 32,000 miles. The belts were changed then.

I didn't notice any noises out of the ordinary. However, when you throw in the normal motor noise, dry clutch rattle and I normally wear ear plugs, I may not have noticed. Only one of the four bearings were actually frozen. The other three still rotated.

I would be tempted to check the bearing numbers to ascertain whether they are the correct parts , if they are not maybe you can take it up with the dealer to explain why. Very lucky a belt did not let go.

[Ken]

They were identical to the bearing that replaced them. Both were made in Italy and were the original bearings. So, maybe 43,000 miles is the life span of these bearings. I still think over-tightening the belts were the cause.