Tming Belt Maintenance on a 2001 Mercury 90, 4 stroke?

[Stamey]

My friend has a 2001 90hp, 4 stroke and has no idea the last time the timing belt was changed. She has not changed it since she bought it. As the voltage regulator caught fire and messed up stuff at the front of the engine, and I'll be working on it anyway, I was wondering if replacing the timing belt would be prudent. I have looked in the service manual on Boat.info and do not see any info about replacing the timing belt, only to check it every 100 hours, or one year. My old BMW is a interference engine and the maintenance schedule for the timing belt is every 50K or you'll be sorry, which is why I am wondering about this.
If there is no replacement schedule do I just look to see if the belt is beginning to fall apart?
Is this an interference engine or not?

Thanks,
Chris

 

[Bamaman1]

Re: Tming Belt Maintenance on a 2001 Mercury 90, 4 stroke?

Chances are this is a Yamaha powerhead installed on a Mercury.

Yamaha timing belts need replaced @ 1000 hours. Hopefully she's got a proofmeter on the boat to tell you the hours. For most users, they really don't use their boats very many hours per year--30-50 hrs.? It takes many years usage to get to that point

 

[Stamey]

Re: Tming Belt Maintenance on a 2001 Mercury 90, 4 stroke?

This is likely a Yamaha as you suggest. I have run across that as I have been researching her voltage regulator fire, and found where someone else, a marine tech, replaced the merc regulator with a Yamaha version for about 20% of the merc price. I, unfortunately, do not have those kinds of reference material to find the Yamaha equivalent.
I will ask her about a proofmeter.
So there is no 1000 hours or X number of years?

Thanks,
Chris