Yanmar water pump belt - excessive wear

[chriscallender]

Hi

I was wondering if anyone has experienced excessive wear on the raw water pump drive belt on a Yanmar 3YM20 or similar.

I'm guessing from the state of the belt that the two pulleys on either end must be a good bit out of alignment, but just wondering if it is a common problem, and any pointers on how to check/adjust.

Chris

 

[earlybird]

When I had severe wear on the alternator drive belt of a 2GM20, it turned out that the crankshaft pulley was rusty. It took me quite a long time to discover this after suspecting misalignment etc.

 

[matelot]

the standard reason for excess wear is that someone has replaced the Yanmar belt with what appears (but isnt) to be the same size from a motor factors. The belt needs to be gripped on the sides not at the bottom of the pulley but the Jap belts are a slightly different cross section - bit fatter with pulleys made to match. So the motor factor ones sit in the bottom of the pulley, start to slip and then wear at a huge rate.

As a second alternative I have had the pressed steel Yanmar pulleys pull apart with exactly the same result.

 

[chriscallender]

Thanks for both replys. To give a little more info, the engine was installed new by me around November/December last year. Since then its done about 80h. So hopefully that rules out the incorrect belt, or rusty/broken pulley.

Maybe 80 hours is all the belts are good for, but it wasn't a 50 hour service item, and all the rubber dust made me think somethings up...

Certainly when I noticed it was looking a bit dodgy, it also seemed a bit slack, so maybe its just been slipping and got trashed that way. Not sure whether the slackness was a cause or an effect though...

Next time I'm donw, I'll have a good look at it for anything sharp/misaligned, and if I can't see any obvious problem, just fit a new belt and keep an eye on things (clean up all the rubber dust, and see if any new dust starts to appear).

Thanks for the help. Mainly I was wondering if I would get an "they all do that" reply, since I was a bit surprised the state it was in on a newish engine.

Chris

 

[Cloven]

Have had same problem with 2GM20F and Yanmar supplied belts were awful - barely lasted a season and lots of black dust.

Replaced it this year with a Gates Extra Service toothed belt. Run all season, negligable wear and NO DUST. Also less than half price of Yanmar sourced belt.

Hope this helps

 

[toad]

Yes they all do that, I have had two Yanmar engines that did this and seen several others with the same problem. All you can do is clean the working surfaces of the pulleys with some emery paper which will delay the problem.
I normally give them a clean just before launching and halfway through the season.

 

[Eventide26]

Would belt dressing spray help?

 

[steve6367]

I had a 1GM that did it - new crank and alternator pully and all was ok.

My new 3YM21 does not seem to suffer the same problems..

Steve