[herbwoodbury1949]

I just had the timing belt/serpentine belt both tensioners and the water pump changed at 90,000 and nine years old. No cracking on either but good to have it done and not worry.

BOTH tensioners???

I just had to replace the engine on a 2014 500L because the belt went at 129K miles. It only had ONE tensioner. I have replaced a whole bunch of timing belts and have NEVER seen 2 tensioners on a car, including a dual cam engine.

As for the seal leaking, there is always a front seal on an engine. I have seen leaks that were around the outside of metal housing on the seal, not the part on the crankshaft, and the use of a silicone sealant would prevent a leak there.

 

[J.B.]

BOTH tensioners???

I just had to replace the engine on a 2014 500L because the belt went at 129K miles. It only had ONE tensioner. I have replaced a whole bunch of timing belts and have NEVER seen 2 tensioners on a car, including a dual cam engine.

As for the seal leaking, there is always a front seal on an engine. I have seen leaks that were around the outside of metal housing on the seal, not the part on the crankshaft, and the use of a silicone sealant would prevent a leak there.

He said "timing belt/serpentine belt." Each has its own tensioner. Probably because he replaced both belts at the same time.
This may sound bizarre, but the belt driven Ducatis have technically two tensioner per belt, one idler and one tensioner. I know, Italians...

 

[herbwoodbury1949]

An idler is not a tensioner. As for a ducati never had anything to do with them, on purpose.
Actually I have avoided European vehicles as much as possible.