Volvo D4 Belt Slipping (Have Changed and Tensioned Belts)

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pistonbroker

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I did a search and could not find this query before, apologies if this has been covered and I missed it. I upgraded my boat this year to a Bavaria 37 Sport with Volvo D4-300s. I am just getting used to it and am so far very pleased. When I bought the boat I noticed a squeal from the starboard engine and at the time thought that it either need replacing or re-tensioned. Long story short, I have replaced both belts on both engines and have re-tensioned them warm as the Volvo manual advises. I do however still have slippage on the starboard engine which has the power steering pump and an alternator.


On engine tick over there is no slip and when I turn hard to port or starboard when stationary there is no slippage. If I get underway, again no slippage through the rev range or under change of direction. I think I have probably ruled out the steering pump now. However I have noticed that in slow speed manoeuvring when using the bow thruster the starboard engine belt starts slipping. Additionally when I use the windlass when anchoring up I get belt slip. This also seems to coincide with a drop in voltage seen on the helm voltmeter. I need to check but I think the starboard engine must charge the battery for these items.

So the question is has anybody experienced this before? Was it a battery issue, or alternator issue, or both? I am assuming at the moment that its a battery problem and that the alternator cannot keep up with the demand and therefore slips under load.

Any thoughts or assistance most appreciated.
 
Hello,

I don’t have direct experience with your problem, but I do have the same boat 37 Sport HT, but with the D6-330s.

If you suspect alternator load is creating the friction can you check the voltage drop when you use the bow thruster without the engine running? The other option might be to swap you batteries over and see if that clears the fault. All this could point to a dead battery.

I take it you know there are different belts for the engines? Obviously the engine with the power steering pump needs a longer belt.
 
Thought the alternators spin all the time .Does yours have a clutch ?
Mine gives out 26.4 V throughout the rev range .Some sort of controller determines what happens and where it goes .
Yours must have some sort of magnetic friction creating side effects when it’s called upon, which increases the resistance of the pulley momentarily = belt slippage ?
 
mcanderson said:
Hello,

I don’t have direct experience with your problem, but I do have the same boat 37 Sport HT, but with the D6-330s.

If you suspect alternator load is creating the friction can you check the voltage drop when you use the bow thruster without the engine running? The other option might be to swap you batteries over and see if that clears the fault. All this could point to a dead battery.

I take it you know there are different belts for the engines? Obviously the engine with the power steering pump needs a longer belt.
Click to expand...

Thanks for the quick reply. Mines an HT too so the arrangements are likely the same. I have 4 batteries which I assume are motor 1, motor 2, bow thruster/windlass and domestic? Good ideas thanks I'll give those ago. Yes got the longer belt for the power steering pump.
 
Portofino said:
Thought the alternators spin all the time .Does yours have a clutch ?
Mine gives out 26.4 V throughout the rev range .Some sort of controller determines what happens and where it goes .
Yours must have some sort of magnetic friction creating side effects when it’s called upon, which increases the resistance of the pulley momentarily = belt slippage ?
Click to expand...

Hi yes the alternators are always on rotation, and no clutch from what I could see. The voltage regulator takes up the role of the clutch to prevent overcharge. I get14.4v on charge but I think the current demand from the bow thruster and/or the windlass are too much for the battery and the alternator is trying to provide the demand instead leading to increased resistance. Appreciate the reply thanks.
 
jim.howes said:
Hi as its not an exact science on how to tension a belt I would try a little more tension on the belt.
Click to expand...

Hi, yes as a general rule but oddly enough Volvo specify a torque figure! You loosen the main tensioner and then apply a torque wrench to a 1/2" square aperture, apply the correct torque whilst re-tightening the tensioner bolts! Bit over the top but I guess specified for a reason. Thanks.
 
pistonbroker said:
I think the current demand from the bow thruster and/or the windlass are too much for the battery and the alternator is trying to provide the demand instead leading to increased resistance. Appreciate the reply thanks.
Click to expand...
Depening on the size of the bow thruster they generally demand around 300 amps so need good batteries,
 
pistonbroker said:
I did a search and could not find this query before, apologies if this has been covered and I missed it. I upgraded my boat this year to a Bavaria 37 Sport with Volvo D4-300s. I am just getting used to it and am so far very pleased. When I bought the boat I noticed a squeal from the starboard engine and at the time thought that it either need replacing or re-tensioned. Long story short, I have replaced both belts on both engines and have re-tensioned them warm as the Volvo manual advises. I do however still have slippage on the starboard engine which has the power steering pump and an alternator.


On engine tick over there is no slip and when I turn hard to port or starboard when stationary there is no slippage. If I get underway, again no slippage through the rev range or under change of direction. I think I have probably ruled out the steering pump now. However I have noticed that in slow speed manoeuvring when using the bow thruster the starboard engine belt starts slipping. Additionally when I use the windlass when anchoring up I get belt slip. This also seems to coincide with a drop in voltage seen on the helm voltmeter. I need to check but I think the starboard engine must charge the battery for these items.

So the question is has anybody experienced this before? Was it a battery issue, or alternator issue, or both? I am assuming at the moment that its a battery problem and that the alternator cannot keep up with the demand and therefore slips under load.

Any thoughts or assistance most appreciated.
Click to expand...

Can we assume the pulleys are all clean, dry and free from oil or grease?
 
how old are your D4’s as I beleive there was an update to replace the old tensioners (?) a quick check with Volvo may help to discount this
 
dulls said:
Just another issue maybe and away from a different angle could you have bearing issue?
Click to expand...

I checked all the pulleys and rollers to best I could, clearly you can't move them all such as the crankshaft pulley (but there would be other issues that would probably emerge from that in any case.
 
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