Tuesday 19 March 2013

Flipping Belts


For the majority of last year we had an issue with a screeching noise coming from the engine bay whenever the supercharger was engaged. This started at the same time as the water leak from the raw water pump. At the time we attributed it to a slipping belt due to it being wet so paid it little attention.

As the water pump was fixed we also tensioned the supercharger and alternator belts however this failed to remedy the problem. So we changed the alternator and supercharger belts for new ones. Still problem not sorted. By this time it was late in the season and we were quickly coming to the conclusion it was a supercharger bearing at fault. A job for the quieter winter months.

In one last bid attempt to not write off the supercharger, which happens to be quite expensive, we changed all four of the belts for new ones at the weekend. This time following the manual to the letter, tensioning the belts in the specified order to the specified torque settings. Guess what? It worked. No more squealing supercharger. Phew, wallet relieved.

It would seem that these engines are very fickle beasts and everything has to be done in the correct order for them to be happy. We must have just been lucky in the past when changing the belts and got the tensions near enough. So lesson learned, in future follow the manual and start with the easy and cheap options when diagnosing problems. In hindsight we would have done this much sooner but you know what they say about hindsight.

3 comments:

  1. Hi, your blog is always interesting and I have picked up a lot of useful information about the differnet places you have been.
    I was however curious how you engage your supercharger, or indeed what your supercharger actually is to be belt driven as I have not heard of this before?
    Regards

    Phil

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  2. The engine in NC (Volvo Penta KAD32) has both a supercharger and a turbo charger. At revs below 1500rpm, which equates to speeds below about 5 knots, so river speeds neither the supercharger nor the turbo charger, are working.

    From 1500rpm an electromagnetic clutch kicks in and means that the supercharger is working whilst the big turbo is spinning up. At 2700rpm the supercharger kicks out and the turbo charger takes over. This reduces the turbo lag and means that a bigger turbo can be added generating more boost and more power.

    It sounds complicated but in practice it is fairly simple to maintain and easy to operate.

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  3. Oh the supercharger is belt driven by the way

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