B47 Alternator Belt Replacement Layout

[Nigel]

I've just changed my Alternator Belt Layout, see picture:


Reasons for doing this:

The 12V alternator (on RHS of picture) is 120A, and gets through (9mm) belts quite quickly. The other belt (24V alternator) has not been changed in 10 years.
The load on the 12V belt was increased by being shared with the water pump.
The new layout reduces the load on this belt, and increases the wrap on the pulleys.
The drive spindle is now slightly smaller, so again this should reduce slippage.

Now I need to measure for new belts:
I was thinking of using some 3mm string with the alternators where I want them to end up, will this work?
How much movement of the pulley should I allow to fit the belts?

The more observant of you will have noticed a problem with the oil pressure sender, more on this in this thread: http://www.bavariayacht.info/forum/index.php/topic,962.0.html

[blue-max]

Very interesting. I want to upgrade my alternator from the standard 60 amp to a 90 amp mastervolt one and doubt the belt will cope - its already given problems coming loose periodically. I was thinking of changing the sheeves to support a flat belt - alternatively adding sheeves to existing might work. I like the idea of 2 alternators - is your 24 volt systemompletely separate from  the 12 volt service ? Mine is shared which I find confussing

[PEA-JAY]

You cannot measure with string as it will sink into the v of the pulley. Ideally use an old belt as a tape measure. Try and find either one long belt or else join two short ones so you are left with a length of 10mm belt which can overlap at a convenient point. You can then lay belt flat and measure. The correct belt will be a 10x whatever the length you need. Belts are normally measured from the outside, example 10x1250 (mm) I think 25mm allowance will do depending on free space around the the various pulleys.

[blue-max]

Nigel
Did you fit the 24 volt alternator or was this done by others? I would dearly like to fit one but looking at your photo and my engine wonder how it was possible to fit in the tiny space. Also can you say where you got the extra sheeve/pulley for the crankshaft

[Nigel]

The 24V alternator was fitted from new. Volvo Penta do a kit, this is the one for my MD22P.

I cut large chunks out of the mounting bracket, not knowing it cost £500!

[blue-max]

Thanks for the info. I have the same engine version  TMD 22P so it should be doable. Do you also use a 24 volt battery charger for when berthed etc and while I have the chance do you use non VP filters timing belt etc?

[Nigel]

... Do you also use a 24 volt battery charger for when berthed etc and while I have the chance do you use non VP filters timing belt etc?

I currently have a rather nasty 24V charger I bought on eBay. You have reminded me I wanted to upgrade it to a CTEK MXT 14 24V, 14A, 8 step, fully automatic charger.

I have a Racor 120AT Diesel Fuel Filter with a 120AT filter element. This can handle 57 l/h, so you need to check your lift-pump throughput.

Timing belt was fitted by A VP dealer, but the engine is a Perkins Prima M50 (I think it's M50). Same engine as in Maestro and Montego.

[blue-max]

Interesting but I think I will have to scour the adds for a old engine with the parts to fit a second alternator. I don't want to pay VP prices. I was wondering about oil filter and engine mounted fuel filter l have a Bosch fitted but can't see a part number