Replacing alternator drive belt.

[pissativlypossed]

Noticed a lot of black dust and small bits of rubber in the engine compartment which i thought was from the alternator drive belt so I thought 'change the fan belt'. Easier said then done.
The engine is a Yanmar 4jh4, I could get the original belt off but no way could I fit the new one, there just wasn't enough movement by loosening the alternator, the handbook says " loosen the water pump v-belt pulley to change the belt" not sure what this means, is there a short cut or dodge I can use?

 

[pvb]

Noticed a lot of black dust and small bits of rubber in the engine compartment which i thought was from the alternator drive belt so I thought 'change the fan belt'. Easier said then done.
The engine is a Yanmar 4jh4, I could get the original belt off but no way could I fit the new one, there just wasn't enough movement by loosening the alternator, the handbook says " loosen the water pump v-belt pulley to change the belt" not sure what this means, is there a short cut or dodge I can use?

Presumably loosening the water pump pulley will allow a little extra slack to slip the belt over the alternator pulley. It's worth buying the best quality belts you can find; Gates are good.

 

[VicS]

I could get the original belt off but no way could I fit the new one, there just wasn't enough movement by loosening the alternator, the handbook says " loosen the water pump v-belt pulley to change the belt" not sure what this means, is there a short cut or dodge I can use?

Presumably the same belt drives the water pump so

Just what it says !

Slacken the bolts that hold the pulley on to the water pump drive flange.

That'll allow the belt to be fitted.

Tighten the pulley bolts againbefore adjusting the belt tension.

It is the "dodge" you are asking for!

 

[Spyro]

Get a longer belt, there must be enough travel in the alternator to allow it if you can't get the belt on when it's loosened.

 

[macd]

+1 VicS and pvb. But whatever you do, don't be tempted to pry the belt on: not good for it.

 

[VicS]

Get a longer belt, there must be enough travel in the alternator to allow it if you can't get the belt on when it's loosened.

There probably is not enough available movement in the alternator adjustment which is why the manual suggests what it does. It may not be possible to correctly tension a longer belt if the adjustment is limited.

 

[macd]

Tip for belt adjustment: if there's room and the geometry allows it, throw away the Micky Mouse standard slotted adjuster and fit a bottle screw (with locknut). Makes adjustment much more precise and simple.

 

[claudio]

It's worth buying the best quality belts you can find; Gates are good.

+1

 

[oldsaltoz]

+1

+ 1 as well.

Green line from Gates is what you are looking for.

The rubber dust is most likely due to some rust on a pulley by the way, so check and clean each pulley when you remove the old belt.

Good luck and fair winds.

 

[macd]

It's worth buying the best quality belts you can find; Gates are good.

+ another.
And, if you're not using them already, notched belts are superior to plain ones because they run cooler. (They're sometimes called 'toothed' belts but aren't really since the 'teeth' have nothing to engage on.)

 

[ghostlymoron]

Are you sure the new belt is the correct length? It will definately be shorter than the one you have taken off because that one has stretched. If the belt drives both alternator and water pump, slacken both off to give you more slack. As suggested previously, clean up the pulleys (dry wire brushing) before fitting the new belt.

 

[stuartwineberg]

This must be a feature of Yanmars - I have a 4LH-STP 230 in my Hardy. Exactly the same problem - loosen both alternator nuts and still the OEM new belt would not go over the pulleys - about 2 cm short in my view. Asked an engineer to do it in the end - not sure what they did, I just couldn't shift it. Will try the pulley bolt trick as suggested if I can reach it - very tight access - thanks for the tip

Presumably the same belt drives the water pump so

Just what it says !

Slacken the bolts that hold the pulley on to the water pump drive flange.

That'll allow the belt to be fitted.

Tighten the pulley bolts againbefore adjusting the belt tension.

It is the "dodge" you are asking for!

 

[stuartwineberg]

Quick google search tells me Gates are USA - can you advise where to get them in the UK?

Many thanks

Presumably loosening the water pump pulley will allow a little extra slack to slip the belt over the alternator pulley. It's worth buying the best quality belts you can find; Gates are good.

 

[macd]

Quick google search tells me Gates are USA - can you advise where to get them in the UK?

Use Google advanced search: http://www.google.co.uk/advanced_search
Specify region 'UK'.
Fill yer boots.

 

[TQA]

Try removing the adjustment bolt completely.

Next step remove the alternator pivot bolt. This is when a third hand would help.

You should now be able to fit the belt.

n.b. this MAY be easier than getting access to the WP pulley bolts.

 

[MrCramp]

Gates are one of the major suppliers of belts to the UK motor industry and, as far as I know, the best quality belt that you can fit.

 

[JumbleDuck]

Gates are one of the major suppliers of belts to the UK motor industry and, as far as I know, the best quality belt that you can fit.

And made in Dumfries!

 

[pissativlypossed]

This must be a feature of Yanmars - I have a 4LH-STP 230 in my Hardy. Exactly the same problem - loosen both alternator nuts and still the OEM new belt would not go over the pulleys - about 2 cm short in my view. Asked an engineer to do it in the end - not sure what they did, I just couldn't shift it. Will try the pulley bolt trick as suggested if I can reach it - very tight access - thanks for the tip

Hi,
I managed to fit the new belt today, by taking of the water pump pulley (it's held on by four bolts) and Also slackening the adjustment nuts on the alternator it's still a tight fit but it did go on. The new belt is the same part number as the old one and exactly the same diameter, the older one has worn slightly thinner and the vanes (?) have worn down being the only difference.
Incidentally, the old belt came off, and goes back on without taking the pulley off so I will keep it as a spare in case it has to be changed at sea in an emergency, I wouldn't want to have to remove the pulley in an emergency situation.

 

[ghostlymoron]

Well done!
I've found that you can usually get a tight belt on by hooking it over the lip of the pulley, then turning the pulley so it all goes over the lip. (Easier to demonstrate than describe).

 

[macd]

Well done!
I've found that you can usually get a tight belt on by hooking it over the lip of the pulley, then turning the pulley so it all goes over the lip. (Easier to demonstrate than describe).

...a bit like feeding a bike tyre onto a rim (which isn't to suggest you use tyre levers, which of course you're not advocating ) I'd say this is legitimate, with care: belts are not designed to accept forces in this direction.