belts

[dway]

I have a Beneteau 44' Swift Trawler with twin 300hp Volvo D4s
I notice that I get a fair amount of black powder from the drive belts
Is this normal? The belt tension all seem good. I did lose the starboard belt a week ago after seeing a continuous accumulation of black powder, there were no actual pieces of belt rubber, just the fine powder. I had both belts replaced but am again seeing black powder accumulating

thanks

 

[Shrew]

Is there corrosion on the pulleys? Are the pulley's aligned properly? Are the bearings good? The dust is from friction. I would suspect the thrown belt and the dust are related.

 

[wpc691]

The belts are slipping. Are you using OEM belts? My boat came with Carquest belts, and I had black powder all over the front of the engines. Switched to Cat OEM belts, no more powder.

 

[Mischief Managed]

Are you running your batteries down between the times the engine are running? The only thing with a variable load is the alternator and if it's working hard, it will cause belt wear.

 

[Capn Craig]

belt slippage

I had the same problem with my old Trojan. It was gas not diesel but that has nothing to do with it. I had changed out the OEM alternator for a 150 Amp Powerline with an separate 4 stage voltage regulator. I used 4 golf cart batteries as a house bank and had a 2000W inverter and no genny I used it often and typically started with fairly discharged batteries in the morning. I bought the big alternator to recharge them while running. At first I heard a bit of squeal when running 1000 to 1500 rpm. I reasoned the belt was slipping under the load. I tightened the belt to a very tight condition. That was not a good thing for alternator bearing life. but the squeeling went away. I was getting a lot of black dust on the front of the engine, still. The belt looked glazed quickly after replacing it. The black dust was actually rubber from the belt. I put up with it for a couple short seasons, and two replacement belts. There is a difference in belt quality. But not enough to make a bad situation better. On the beginning of third season I adapted to a double belt drive. All problems went away. And, I didn't have to over tighten the belts any more. Problem Solved.

 

[dway]

thanks for the tip
still not sure what is going on, I like the alternator working hard thought since we did have a period where our aux battery charger failed and the house batteries would get low. They would charge up when running the engines. I just don't like the thought of loosing a belt when out in the middle of nowhere on a 60 mile run. When we lost a belt last week we were only 4 miles from the reef and marina. Thanks for all replies, I'll keep an eye on it and when I get back to Florida have it looked at.