4JH3 Yanmar alternator belt

[jonathanovision]

So I'm trying to replace the alternator/water v-belt
its a REMF 6460 belt,( I think the yanmar part number is 25132-004600) and to say it is tight is an understatement. I've even tried taking the water pump sheave off, but it is ridiculously tight. The alternator is what tensions the belt and it is shoved right against the engine.

Anyone else have this issue?

[Lepke]

Get a bigger belt. If it's tight with no adjustment, it will wear fast. You don't need a Yanmar belt, they didn't make it anyway. Most autoparts store belts will do.

[skipperpete]

Definitely ease off the tension or the circulating pump will suffer. Try and get the equivalent Gates “green stripe” belt, they really last an amazingly long time.

[dksail]

I replaced that belt last year with the same OEM part number you listed. I did not find it to be tight. We have a Balmar alternator. Perhaps the alternator and associated parts have been changed on your engine?

[Smokeys Kitchen]

Originally Posted by skipperpete

Definitely ease off the tension or the circulating pump will suffer. Try and get the equivalent Gates “green stripe” belt, they really last an amazingly long time.

+1 on the Gates Greeen Stripe belts. They work well - as well as can be expected for a single v belt - and seem to last a long time.

[foxfire]

Originally Posted by jonathanovision

So I'm trying to replace the alternator/water v-belt
its a REMF 6460 belt,( I think the yanmar part number is 25132-004600) and to say it is tight is an understatement. I've even tried taking the water pump sheave off, but it is ridiculously tight. The alternator is what tensions the belt and it is shoved right against the engine.

Anyone else have this issue?

If you have trouble with a high output alternator burning up V belts like I did you can buy a conversion kit to change over the alternator, water pump and crank pulleys to a poly-vee (flat style) belt. Tension it once properly then forget about it! About $400 a kit but great peace of mind, no more shredded rubber chunks in the engine compartment, no more squeezing and burning belts, and full output from your alternator. I love it!

[ShawnMack]

This may sound very basic but I more than once I've been sold the wrong belt because it was stuffed in the "right" sleeve. It may be worth checking the actual number printed on the belt.

Another nod to Gates Green Stripe belts. They just seem better, regardless of price.

[jhulmer]

I have that engine and stock 80amp alternator. It can be difficult and I have had to use a socket wrench to roll over the engine with the belt on the edge of the last pulley to get the belt on. It was fine after that and the OEM belt will stretch a little after running awhile. BE SURE to depress the fuel cutoff plunger on the engine while you roll it over as a precaution. (I really doubt the engine could start unless just shut down BUT!) This engine will run with the start key in the off position!


Put me down as a plus on the GATES belts also.



Welcome to the CF!

[Dsanduril]

Originally Posted by jonathanovision

So I'm trying to replace the alternator/water v-belt its a REMF 6460 belt,( I think the yanmar part number is 25132-004600) and to say it is tight is an understatement. I've even tried taking the water pump sheave off, but it is ridiculously tight. The alternator is what tensions the belt and it is shoved right against the engine.

Anyone else have this issue?

REMF 6460 Outside Circumference = 47.27

25132-004600 crosses to A46 (at least in my book) Outside Length = 48

That 3/4" can make all the difference.

[Captain Scott]

I have this engine and I noticed that same belt that did not fit both sides (?!?). Turn out one of my alternators had a slightly narrower pulley on it, which requires a longer belt for a proper fit. Hope that helps.... and THANKS for all the Gates green strip refs, I will give those a whirl. -S

[Alita49DS]

I have a 4JH and, bluntly, a V belt is not fit for purpose. Hence the newer engines all coming with serpentine belts. Flat with grooves.

I replaced the V with a kit from Electromaax. Cheaper than Balmar and could not have been more helpful about the pulleys and the fit.

Unless you like black dust everywhere and paying for belts that need to be regularly adjusted I would strongly suggest taking the same route.

[WindyWanderer]

Ahh.the belt on my yanmar....time to change it and it will be a pia, but i found a new trick that works!

Ive owned yanmars in all my boats, great engines, but the belts change seem to be consistently a challenge no matter what model or year. It should not be so, but for some reason...

First, for your engine you'll need to do the experiment posted above. Measure your existing belt that works, preferrably when new and not stretched, then go to gates and purchase lengths that slightly bracket your overall belt outer length. I usually buy 3, and hopefully one of them is just right. Its required only once for each engine config, but your first 3 selected may not be right and you may have to try again.

BUT, on all on my yanmars so far, there's never one that fits perfect, that allows easy on/off and tensioning. The one thats best always seems too tight and a struggle get on/off, but tensions perfectly.

You would think that the yanmar belt would be perfect, but ive purchased so many, i have a bin of new ones that are unusable; there are always too long/ short, thats why I go to gates.

So heres the issue, even the best belt will be a struggle to put on, unless I use a new technique that was suggested by my wife! Works great, everytime with the identified belt.

Here it is, engine in neutral, remove old one, clean the 3 pulleys, take the new belt and put in boiling water for about 3-5 minutes, remove from water, place belt on crankshaft and alternator pulleys, on the camshaft pully it will still be tight but you can start v in groove. I start on the crankshaft side of the pulley. HERES THE TRICK, twist the belt upside down and PUSH THE FLAT EDGE over the pulley. The belt is on but twisted. Now on the downside of the belt from alternator to crankshaft, grab the belt and rotate the crankshaft CW looking at engine, until the v in the cam pulley completes route around the pulley and the twist is released.

And Voila! Its on! The cursing ends, no crowbars or broken brush handles, or broken electrical connections or smashed knuckles. Just tension by positioning the alty, and you good to go! New belt, np sqealing, will last typically about a year with intermittent tensioning as the belt ages.

I love her, both my wife (she's awrsome) and my yanmar especially now t v at I can change the belt with ease, everytime!

Hope this helps you fellow sailors. I don't post anything much but had to share this with others struggling with their yanmar belts.

Fair Seas

[Nord Sal]

Originally Posted by Dsanduril

REMF 6460 Outside Circumference = 47.27

25132-004600 crosses to A46 (at least in my book) Outside Length = 48

That 3/4" can make all the difference.

Originally Posted by Lepke

Get a bigger belt. If it's tight with no adjustment, it will wear fast. You don't need a Yanmar belt, they didn't make it anyway. Most autoparts store belts will do.

Take your old belt to an auto parts house. They'll have a gage to measure its overall length. Get a new belt that slightly longer, say 1/2" to 1" max. You may have to try a couple different lengths to find the one that fits "just right."


I had to go to a belt that was 1/2" longer when I replaced my alternator.

[jdazey]

Originally Posted by foxfire

If you have trouble with a high output alternator burning up V belts like I did you can buy a conversion kit to change over the alternator, water pump and crank pulleys to a poly-vee (flat style) belt. Tension it once properly then forget about it! About $400 a kit but great peace of mind, no more shredded rubber chunks in the engine compartment, no more squeezing and burning belts, and full output from your alternator. I love it!

Originally Posted by Alita49DS

I have a 4JH and, bluntly, a V belt is not fit for purpose. Hence the newer engines all coming with serpentine belts. Flat with grooves.

I replaced the V with a kit from Electromaax. Cheaper than Balmar and could not have been more helpful about the pulleys and the fit.

Unless you like black dust everywhere and paying for belts that need to be regularly adjusted I would strongly suggest taking the same route.

If you're putting a large load on the alternator (large battery bank), the serpentine belt conversion will save you a lot of grief. +1 for Electromaax even if they are a bit slow at times.