Kad 32 advice required re unusual compressor noise.

[enterprise]

Returned from a great weekend, didn't manage to go anywhere due to the wind however we started and ran our engines up to temp at our berth.

First time we have noticed this and perhaps it's something that owners can advise upon, we have twin Kad32's, port engine runs fine, increasing the rpm's gradually untill the compressor kicks in at 1700rpm, all ok, everything as should be.
Starboard engine runs fine but when increasing the rpm's again to 1700, compressor kicks in ok but there is a vast difference in sound to that of the port engine, sounds like the charge air is escaping is the only way of describing it, ie compressed air leaking sound, engine temp is a fraction higher than the port engine but all other gauges are the same and are normal.

Not taken her out for a while so wouldn't be able to confirm any performance issues, have called our mechanic today and highlighted the noise issue for him to take a look while doing the annual service, just wondered if anyone had seen (heard) this from a Kad 32 before?

 

[Peanuts]

Hi

Not the usual problem with drive belts then as you say the supercharger is cutting in at the correct RPM. You mention it sounds like a compressor air leak, could you not set the throttle with the supercharger working and then feel around the pipework from the supercharger around the engine. If you cannot do that then it is not a problem to check the pressure using a pressure gauge connected onto the intake manifold, throttle set at 2000rpm and it should be reading 10psi.

I hope that is of some help but whatever the outcome please post back to let every one know what the problem was.

 

[scottie]

The only work the engine is doing in neutral is battery charging and on twin screw one engine will be doing all the house charging which may give some difference in engine note.

 

[enterprise]

We are about to have the annual service done so have commented on the unusual noise to our mechanic, would ordinarily have investigated but ran out of time yesterday and because the engineer will be onboard before we are next onboard ourselves the question here was posted out of curiosity.

Engines run exactly the same until the compressor kicks in so not linked to charging etc, all was fine on last trip out (around three weeks ago)

I'm sure someone will have experienced the same symptoms, so wondered if it was common, as said we have 2 so noise comparison is quite easy.

Will report findings when we know more.

 

[Elza_Skip]

We had 2 different "odd" noises with our KAD32s.

Firstly if one of the 2 main belts is not adjusted just right or worn then you will get a squeal as it slips

The second problem was when the feed pipe from the compressor can off the y piece behind the air filter (I think I stepped on it). This created a low pitch sound of rushing air.

I hope this helps

 

[volvopaul]

The drain hole in the intercooler can become blocked so not allowing a passage of air through it, also the rubber hose on the turbo inlet can split allowing air to escape, these all add to the ambience of the engine.

 

[aquatom]

It's common for the outlet elbow on top of the supercharger to leak air from the back under where the pipe attached (it's a easy job to reseal this). Also check all hose connections between supercharger outlet, through 'y' valve, through turbo and into inlet manifold. The connections on the 'y' valve and the elbow entering the turbo often leak.