Yanmar - 3GM Engine belts question.

BobnLesley

BobnLesley

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Our boat's fitted with a Yanmar 3GM30F Engine for which I'm trying to source new alternator & waterpump V-Belts; is there anyone out there who can confirm the belt sizes?
I believe the alternator one is a 10 x either 950 or 975mm, and the water pump's is about 8 x 500mm, but there are no sizes/references marked on the originals I'd like to be sure before ordering.

Thanks in advance, Bob
 
BobnLesley said:
Our boat's fitted with a Yanmar 3GM30F Engine for which I'm trying to source new alternator & waterpump V-Belts; is there anyone out there who can confirm the belt sizes?
I believe the alternator one is a 10 x either 950 or 975mm, and the water pump's is about 8 x 500mm, but there are no sizes/references marked on the originals I'd like to be sure before ordering.

Thanks in advance, Bob
Click to expand...

On our 3gm30 there are some alternative belts available - with NOT quite the same profile as the pulleys, though the length & tension seem OK. One comment I found useful was that belts made by mitsubishi - for Yanmar were a better fit. Can't quote you numbers unfortunately, but it is a bit of a false economy getting slightly cheap belts which are not quite right....

Graeme
 
We have a Yanmar 4JH and I went into Halfords to source replacement belts.
The bigger branches have most of the range on display and it was easy enough to find the right one. (At first I didn't get the length right but took it back and exchanged it until I got the right one.) Just went on width and length.
 
Yep width and length rather than original component.

My local motor factor was soon able to find a identical one (for a lot less than Yanmar original). Bought a couple whilst at it.

Mine's a 3GM30 Raw
 
Yanmar 2GM20F & 3GM30F use same size belts. I have the former. Best belt by far is this one:

Gates Extra Service
No 6469 EXL AVX 13x975 La

So length is 975mm & width 13mm. Order/buy from your local auto factor at a fraction of the cost of the Yanmar belt. Its a toothed belt and works really well. I have had the same one on now for 5 seasons with no problems at all.
 
I replaced my alternator belt with one from the autoshop, the proper yanmar belt threw off so much dust and wore out quickly. I wouldn't fit another yanmar one even if it were the same price.
 
davewarburton said:
Yanmar 2GM20F & 3GM30F use same size belts. I have the former. Best belt by far is this one:

Gates Extra Service
No 6469 EXL AVX 13x975 La

So length is 975mm & width 13mm. Order/buy from your local auto factor at a fraction of the cost of the Yanmar belt. Its a toothed belt and works really well. I have had the same one on now for 5 seasons with no problems at all.
Click to expand...

I couldn't get hold of this one at my local motor factors, but got a Gates 6218MC (950x10) instead, which works fine.
 
The main belt on my 3GM30F is 963 x 13 and the water pump is a Mitsuboshi M19. Again I got from Maccess at about £4 compared to the £20+ for a Yanmar one.
 
As pagoda has said, motor factor belts are not the same profile. They work initially but start to slip fairly quickly in my experience. Best thing is to go along to your local branch of Fenner Power transmissions ( look in yellow pages) with the old belts and they will match exactly and at trade prices
 
I have 2 3GM30 engines, but they need different sized belts as they have different alternators. I use a notched v belt which I get from autofactor. Their measurements differ from manufacturer to manufacturer and whether they are measuring inside or out. Much better to take old belt, even if it has had to be cut.
 
BobnLesley said:
...the water pump is a Mitsubishi M19...

Thanks for the information, but can anyone provide me with the dimensions of the waterpump belt?

I'm in the boondocks of Greece, where thy've never heard of an 'M19' - actually, I'm not sure they've heard of Mitsubishi.
Click to expand...
Yiannis Vardakis, in Kalamata, sourced a replacement water-pump belt for me, a Continental Rubber one which cost €6.

they are difficult to get being thinner than the standard belt which is easily found in any Greek town of any size by going along to the local motor-factor with the original as a template. I got one in Korinthos for €5 which did perfectly good work until the inferior pressed-steel yanmar pulley decided to wear its centre flats away.

PS the 3YM and 3GM use the same water-pump belt - Marine Power charge £13 for the genuine Yanmar one.
 
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