V-belt for Yanmar 3GM30F fresh water pump

ggrizzard · Jan 3, 2019

You could take the current belt to a West Marine store and they could match it.
Or go to Defender's web site and specify the engine model number.
But, unless you are on a lake, I think you re looking for the RAW water pump belt.
Be careful of going to a local auto parts store, as they sometimes don't recognize the importance of the width of the belt. Once, a NAPA store tried to convince me that a wider belt was better. Wrong!

Stu Jackson · Jan 3, 2019

ggrizzard said:
Be careful of going to a local auto parts store, as they sometimes don't recognize the importance of the width of the belt. Once, a NAPA store tried to convince me that a wider belt was better. Wrong!

The REAL trick is LEARNING exactly what belt you have and, sometimes it's different, what you NEED.

Find the width (easy) and the length. Then, write it down.

I've always purchased my belts at a NAPA store, Gates brand is quite good. There are some better and I'll let the specialists here inform you of those other choices (i.e., grooved and other names).

My belts are 3/8" 7395 length. I've tried 7390 too short and 7400 too long. There are a much longer string of numbers on the outside flat face of the belt which a shop can find helpful.

Good luck. Buy two or more once you've found the right ones. Don't bother to keep the old as a spare. If you're gonna go to the trouble of putting a new belt on your alternator, put a new one on! Like, always.

Voice of experience...

kloudie1 · Jan 3, 2019

Yanmar Part # is 104511-78780 M19 inch belt, I cross reference to Gates 6719

ggrizzard · Jan 3, 2019

Alternator belts and the raw water pump belts are different. But I agree, it is better to put on a new belt, unless an old one is all you have.
And, BTW, you should re-adjust the tension of any new belt after a couple of hours of running after install.

Rick · Jan 3, 2019

Summatime
Shoot me a PM. I had a 95 336 for 13 years. Sold it not too long ago. I believe I have some info you might want.

Cheers
Rick

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Stu Jackson · Jan 3, 2019

Summatime said:
Any idea on how long until I should be thinking about replacing the belts? annually or miles,
Is there any rule of thumb?

Could well depend on how you use it. Marina hopper: bank is usually full, no load on alternator when starting to motor. Anchor out even for two nights, if you can electrically, then there's a load. Of course, the belt is always going around. Keep looking at it, good habit. I've gone many years on belts, 2, 3, 4 at most. Avg. 100 hours per year, more lately.