Alternator belt replacement

Roberto

Roberto

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Lorient/Paris
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I have two alternators, each one has a separate belt: both belts are functioning well, no black dust residue, no schrieking noise, they keep their tension, etc. I might well leave them there but they must be 3/ 4year old.
Is there a recommended period after which they must be changed ? I rather prefer preventative maintenance than repair, but as those two belts are quite awkward to replace I would like to know the average service time one can expect... if it exists /forums/images/graemlins/crazy.gif
 
Take a look at the inner side of the belts; are they cracked, shiny, any teeth missing (if they have teeth like on mine)? If any of the above, change them. If they don't look too bad after you have taken them off, keep them as spares. It's recommended for my boat that belts are changed after every 100 hours of use. Better preventative changes with belts in my view, even if they are a problem to get at. It's easier than at sea!!
 
Hi Roberto

Same boat and I guess same Yanmar 44 with 2 alternators plus smart regulators too in our case. I have our engineer change both our belts routinely as part of the annual service, it takes him only about 15 minutes (I'm there when he does it) and I keep the old belts as spares as they are usually in good condition. I prefer to spend just a few pounds on the new belts and not perhaps have to change one at sea.

We have quite a few used pump impellors and alternator belts in 'stock' as you might imagine!

Robin
 
Yes I understand how you feel, I do replace the boats belts every year at service time but I have to say its probably OTT!
Ask yourself how many times you replace the belt on your car? and I bet you use the car every day!

Just keep a good eye on them,

Barry
 
Your car probably has a proper polyvee belt, rather than the primitive rubbish boat engine manufacturers fob us off with. And the car belt will usually have less power to transmit since charging cycles are typically far less deep.
 
May I have your old belts please.

The worst case scenario is losing electrikery for a short while while you change a broken belt. Change a water pump belt when it shows wear, but annual changing of alternator belts seems a definite over kill, IMHO.
 
What may be an answer to your concern is to put a replacement in place but tied back against the engine block such that it can be pulled onto the pulleys in place of the original if it fails. (breaks).
I don't know why you find it difficult to replace a belt but this idea may help. It is standard practice on light aircaft where the belt goes around a pulley on the prop shaft. so you have remove the prop to put on a new belt. So they fit an extra tied back behind the drive pulley. Just a thought olewill
 
thanks all

The engine is a Perkins (much older than yours Robin I guess -.;), there is one alternator belt driving the water pump together with the original alternator for engine battery; plus another pulley bolted on the crankshaft driving a more powerful alternator with a shorter belt, for the service battery bank.
The two belts are above one another in a position such that if I need to replace the first belt (the most important, as it drives the engine water pump) I have to dismantle the shorter one first... I ll try to see if I can put a spare one like William said

anyway, now I know mine are old enough to be thanked and replaced

cheers r
 
Tied back spare belts is also common practise on coaches and buses where lots of parts need dismantling to fit new belts.
If you have ever laid under a vehicle at the side of the road in snow on a cold dark winter night, you will know what I mean!
 
The cogged belts belts last much much longer than the plain V belts.

I have an old Volvo car in which I replaced the plain belts shortly after I had it with cogged ones. That was in the mid 1980s and they are still on there 20 years later!

The cogged ones tend to squeal or shriek under load if they get a little slack.

Next time you decide to change them fit cogged ones and forget.
 
When I acquired my boat, the belts were the thickness of string and lasted about 3 months /forums/images/graemlins/mad.gif
By trial and error with the help of my local Automotive shop I got thicker belts of the correct diameter. These now last about 3 years /forums/images/graemlins/smile.gif
Even then, they don't ware out as such, they suffer from stretch and I run out of adjustment.
The longest belt that suffers most is behind two other belts (I have a 12v & a 24v alternator), so as others have done I keep a spare belt in situ and tied back.
So in answer to the original post - I think it is a pointless exercise to replace every year.
Check twice a year - yes
Carry spares and the tools to do the job - yes
Only when they have been on a few years will you get some idea of the 'Mean Time Between Failure' /forums/images/graemlins/grin.gif
 
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