Same alternator belt for 8 years

[NPMR]

I was looking through the list of repairs and additions I've made to the boat and it's bits (I write stuff in a big book - a bit sad, but useful!) and it turns out I still have the same alternator belt that was fitted in March 2003!

Still looks OK. Just how long can it last? We use the engine for harbour manouvering and when we have to but otherwise try not use it. But occasionally, it gets a good work-out - including a 30 hour run back from France this summer and several other motoring journeys across the Channel over the years (we rarely seem to get the wind we want!)

Obviously I carry a couple of spares but if it works, I tend to leave it alone. Bur I'd rather change it in the yard than at sea. As they're cheap - just do it?

 

[pvb]

How often would you expect to replace the alternator belt on a car, which gets far more use than your boat?

 

[greenalien]

Leave it alone - you might even get more of a problem with a new belt than the old one, as you will have to tension it, let it bed in and then tension it again - it's getting this tension absolutely spot-on that's essential with alternator belts - too tight and they'll overheat and snap, too loose and they'll slip.
If it's working OK, inspect it annually for cracking, and keep an eye out for black dust being generated when it's running - a little from a new belt as it beds in isn't unusual, but if it's previously been clean and then starts making dust, it's probably on its way out. Do always carry a spare belt or two, of course, and if you've never changed the belt, be sure your replacement is the correct size - if the engine was fitted with a replacement alternator at some point, the belt may be a different size to the original fitment.

 

[SHUG]

If you remove it and bend it back you will see if it is cracking up on the inside surface. You will not see this problem on the outside as there is usually a tough layer of canvas ther.
If there are no problems....good luck to you!!

 

[Ricd]

My belt was last changed in 2007 by previous owner. It looks perfect and there is no sign of any fine wear dust anywhere around alternator area or engine compartment so its obviously not loosing significant material. I look at it and like you wonder how long can it last...

 

[Stu Jackson]

Good for you. If your alternator or tach starts acting erratically, change the belt. I had a lot of squealing and couldn't maintain belt tension. New belt fixed that.

 

[DerrickHigton]

Mine is still going strong after 32 years at about 40 hours running per year.

 

[Scotty_Tradewind]

the local engine mechanic in the yard advises slackening off the tension when you winterise.

 

[Jim@sea]

I would go through the excercise of fitting a new one. If yours does go it will fail in the middle of a rough weather trip. I would also consider fitting a new cambelt if yours has one.

 

[fisherman]

I change them every year, just because they are awkward to do and bring me to a dead stop if they fail. Had one failure at just over a year, but after a winter lay up. I sold a boat which had been unused for 5 months. I did several hours delivering to Falmouth to try to show any problems, but the belts gave up mid channel in the dark after another ten hours. Due to rusty pulleys, probably.

 

[Stu Jackson]

First change for me 1998 when boat was purchased, last change in 2003 with new alternator, new belt installed early 2011. Slight slipping eliminated with new belt. Your boat, your choice - what works for anyone else may not work for you.

 

[davidej]

I
but if it works, I tend to leave it alone. Bur I'd rather change it in the yard than at sea. As they're cheap - just do it?

You can say that about hundreds of items onboard.

I sold my boat a couple of years ago and the belt had never been changed in 20+ years.

Unusual - I don't think so

 

[sailinglegend420]

Like most things it depends on how much use they get and how many amps the alternator is required to deliver, and for how long. I was surprised to discover that my new 100amp alternator takes 4 HP from the engine at full load - which required me to up the pulleys and belt from 1/2" to 5/8". I decided it was much cheaper to stay with a 1/2" belt and change it every year.

 

[VicMallows]

I was surprised to discover that my new 100amp alternator takes 4 HP from the engine at full load -

I assume that was at 24v? .... in which case surely about what you would expect?

Vic

 

[LadyInBed]

I was going through about two a year till I found the 'correct' ones.
I put the current set on about four years ago and are lasting well.
My setup is slightly unusual as I have a 12v and a 24v alternator, the 12v is quite long and drives the 24v belt. Not an ideal setup.

In my quest to find belts that would not break and buying some that I thought were the same length as previous ones then finding that they would not fit! I discovered that belts can have the same length code but with different suffix letters. The significant difference was that one indicated inside diameter and the other outside diameter

 

[VicMallows]

The significant difference was that one indicated inside diameter and the other outside diameter

...or even the 'pitch length' which will lie somewhere in between.

I've given up trying and resort to trial-and-error. You end up with quite a few belts in stock for the next application.

Vic

 

[PeterGibbs]

Still looks OK. Just how long can it last? We use the engine for harbour manouvering and when we have to but otherwise try not use it. But occasionally, it gets a good work-out - including a 30 hour run back from France this summer and several other motoring journeys across the Channel over the years (we rarely seem to get the wind we want!)

QUOTE]

When the belt is approaching its end, it is unlikely just to shred without warning. Assuming you check that end of the engine regularly you will see the first signs of degradation when rubber dust begins to accumulate beneath it - that's the moment to whip out the replacement.

My belt is still doing well after 12 seasons so there's no x year rule in this matter.

When replacing, remember to apply a lever to the alternator adjustment so the belt is pretty tight - it should deflect a cm or so with two finger pressure. Slippage from undertightening is the death of belts.

PWG

 

[KenMcCulloch]

My previous boat came with a spare alternator belt which the seller assured me she had had since the engine was installed in 1998. The fitted belt seemed fine and was still in excellent condition when I passed the boat on earlier this year.