Kad 32 Supercharger issue

[Overdraught]

Have a problem with KAD 32's. The superchargers are not operating at the correct RPM's and appear to be cutting in and out periodically. Applying WOT from start she gets to 15 knots and then stalls at this speed until the turbo's get going. Then no problem to 35 knots.

Coming back from Weymouth to Poole yesterday in rough conditions meant lots of throttle control, however the power wasn't there when I needed it i.e. when turbo had dropped off the supers weren't cutting in again. This wasn't huge fun!

This issue was supposed to have been fixed and the engineers are coming out this week. In the meantime I thought someone on here might have some ideas?

Thanks

 

[Nautorius]

Sounds like your belts are slipping. Two seperate belts drive Supercharger and Turbo but they are linked. If one starts slipping this will happen. Common issue with Kad 32's...and cheap to fix!

Chears

Paul /forums/images/graemlins/smile.gif

 

[Overdraught]

Let's hope so. The initial problem was diagnosed as a micro switch(?). The engines have just been serviced so maybe the belts do need some further adjustment.

Thanks a lot

 

[alt]

Check for slack on the belts. There should be about 5-10mm play when you push down in between 2 pulleys

 

[spannerman]

The cut in / cut out rpm for the supercharger is taken from a signal from the alternator, it goes without saying that if the main belt from the crank pulley up to the waterpump is slack it will throw everything out as all the other equipment is driven via this belt. pretty certain this is your problem.

 

[volvopaul]

I thought the charger cut the relay in from the speed sensor not the alternator, will look in my book.

Hope all well in Norway.

 

[[2068]]

It's my understanding that there's a seperate speed sensor. Also a "full throttle" microswitch. And a small adjustable "pot" on the relay box that adjusts the (upper?) cutout speed.

Having said all that, slipping belts can produce some very weird effects, so worth checking first.

 

[spannerman]

Maybe you are right, I just know that recently we have had several with tacho problems and erratic supercharger cut in/out speeds and all of them were due to the main belt slipping, which then lowers the alternator speed which gives the signal for the tacho.
Yes things are fine here, busy giviing all the boats their end of season service and preservation before putting them to bed.

 

[Peanuts]

There is an engine speed (RPM) sensor fitted and is used for controlling the supercharger engine speed relay. There is also a position sender (thats probably the microswitch you mention but it is not technically one) but that is only in operation at full throttle position.
However getting back to your original question, as everybody has stated and you could probably put money on it being the main belt from the crankshaft. I also noticed your statement the engines had just been serviced, sounds like the correct torque loading (35-40Nm) was not applied to the tensioners.

Steve