Yanmar 3gm30f alternator belt

ianybw

ianybw

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Hi,

I am trying to replace the alternator belt on a yanmar 3gm30f. I have the correct part from a Yanmar dealer ( its a proper Yanmar belt ). The trouble is even when I slacken off the alternator mounting bolts and slide it down toward the engine I still cant get the new belt on. It just seems too tight.

The pulley looks original. The old belt, although still serviceable, is cracked. It has either stretched or is just a longer belt.

What do I do? Lever the new one on with a screwdriver. I dont want to damage the shaft. Or do I just go down the parts shop and get a bigger belt?

Thanks In advance.
 
With the engine decompressed, ease the belt over the top pulley while feeding the belt by rotating the bottom pulley, having already got the belt on the crank and alternator pulleys. I think you will find it will go on, always did for me.
 
The size of the old one should be imprinted on it. See how it compares with the new one. You should not have to force it at all. You should also always carry a spare.
 
Do these things not stretch over time, its a good 1+1/2 inch difference.

I liked the idea of squeezing it on, but its hard to believe its correctly sized for the pulley wheels.

Oh well, another trip to the boat and back to get the old one off and bring it back for matching..........
 
They should hardly stretch at all. If there is a 1 1/2 inch difference you have got the wrong belt. If you put a belt on too tight it will wear the bearings out on the alternator, and that will cost a lot of money to replace.
 
Yes, its the wrong belt. Returned it to the Yanmar dealers yesterday, bought two belts for half the money from a car parts shop. Correctly sized, they fit fine. Chandlers, *&^$#@, who needs them......
 
Could you please post the make/part numbers from the motofactors for the future benefit of all us other 3GM30 owners. It would be greatly appreciated.

Thanks

Mike
 
No problem.

For what its worth:

Lordco FHP v-belt 4L410

@ 5$ each, thats 1/5 the price of a Yanmar one. Yes, I know, you get what you pay for. Well its just a bit of rubber with steel strands in it, space age stuff.

Better be careful though, its already been mentioned by somebody else that different engines require different belts depending on the size of wheel. If I was you I would just take an the old one along to any spares shop and get them to match it.
 
In case anyone else finds this thread, there must be more sizes out ther! I had the same problem of the yanmar replacement 37 inch) being too small, but the POs 4L410 spares being too long. A 39 inch belt appears to be correct for my setup. As the boat is 35 yrs old I don't know the history :>)

Reds

Mike

ianybw said:
No problem.

For what its worth:

Lordco FHP v-belt 4L410

@ 5$ each, thats 1/5 the price of a Yanmar one. Yes, I know, you get what you pay for. Well its just a bit of rubber with steel strands in it, space age stuff.

Better be careful though, its already been mentioned by somebody else that different engines require different belts depending on the size of wheel. If I was you I would just take an the old one along to any spares shop and get them to match it.
Click to expand...
 
Just bought two for our Yanmar-£4.00 each from Interpart in Didcot.

Yanmar price 3 times that plus the vodka and tonic........................................

The ones I purchased are genuine Gates belts-pretty much as good as it gets.
 
rotrax said:
Just bought two for our Yanmar-£4.00 each from Interpart in Didcot.

Yanmar price 3 times that plus the vodka and tonic........................................

The ones I purchased are genuine Gates belts-pretty much as good as it gets.
Click to expand...

Here's a excerpt from my Notes, with alternative suppliers for various Yanmar 3GM30F bits. Hope it's useful

Engine
Oil Filter: Cooper Z1142, Fram PH6811, Solid Ace H102003 Knecht OC115
Water Pump Impeller: Jabsco 22799-0001B, Yanmar 23007-4133
W/Pump Belt: 482 x 10 (Yanmar 104511-78780)
Alternator Belt: L 970 cm x W13 mm. Yanmar 25132-003700, Gates 6218MC (950x10)
Fuel Filter: Yanmar 104500-55710. AC Delco GF771, Coopers FSM4110, In-Line Filters FBW-PF937.
 
My Kubota takes a Gates 6218 mc too.I think I got three spares for under £10 at the local motor factor.Similar story with oil and fuel filters.
 
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