Problem with KAD32 (no power)

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banflu1

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Hi all,

I’ve been searching on this forum for quite a while trying to find a solution to my problem.
But I had to post my own thread as the ones I read either had different symptoms or had the same symptoms but the OP never posted a final solution.

I have a 2003 Cranchi Turchese 24 with the 170hp KAD32 with duoprop.
My problem is this.. the supercharger is cutting in correctly at 1700 rpm and at this point the power from its boost can be felt clearly. The boat is powerful and responsive up until 2500, at which point the supercharger (correctly) turns off. At this point, the boat loses power and the revs drop again to around 2000 rpm.
If you give it enough throttle, the engine starts this cycle automatically:

1700 rpm supercharger comes on
Revs climb up to 2500 rpm.
Supercharger turns off
Revs drop to 2000 rpm
Supercharger turns on again
Revs climb to 2500
And this keeps repeating indefinitely

We installed a boost gauge now and tested it again. The needle climbs up to about 23 psi with the supercharger on at 2500 rpm but it drops immediately to about 10 psi when the supercharger turns off.

If you give it full throttle, the supercharger turns on and remains on. Revs will climb up to 2800 rpm max. The boat is planed at this point. But if you let go of the throttle just a little bit, the supercharger turns off again and revs drop and the cycle restarts.

As a brief history (maybe insignificant, maybe not).. I’ve had the boat since last year. Last year I serviced it before launching and I had zero problems with it. It was powerful and responsive throughout the rev range and I was very happy with it.
During the winter time I replaced the engine soundproofing as it was all disintegrating into the engine room. I bought high quality Vetus sheets with a layer of lead in between the foam, and later I calculated that I added about 180 kgs with this.
I also serviced it again (oil, filters, etc)
The mechanic found traces of diesel bug in the fuel filters. We treated it with special treatment and recirculated the fuel through a filter for a few hours after a few days (before launching). The mechanic told me that this time he only found minor traces.

After launching I immediately felt the boat slightly less responsive than last year. I attributed this to the additional weight. I started to think that maybe I made a mistake with the heavy soundproofing.

Throughout the summer, eventually I felt the boat become more and more sluggish, until it came to this.

Both my mechanic and I suspected the turbo is bad. The previous owner had replaced it just a year or two before, with a brand new original
BorgWarner turbo. He had given me the old one. I had the old one reconditioned locally (new kit and new sleeve in the exhaust housing). The guy who did it assured me it is as good as new (I had used this guy before).
We installed the new turbo and the same symptoms persist. Both my mechanic and the turbo repairer told me that the turbo we removed from the boat appears to be in ok condition. However, my mechanic insists that I need to buy a new turbo and this should solve the problem.

To be completely honest, today it wouldn’t even manage to climb to 1700 rpm for the supercharger to engage. To do this I need to apply full throttle so that the supercharger contact switch becomes activated.
I’m assuming that this is because the hull is now a bit fouled since the boat has been in the water since May. I’m looking for a diver to clean the hull for me then I will retest and post updates.

I’m suspecting a problem in the fuel system as even with 90 or 95% throttle (just enough for the switch not to be activated) I barely see any smoke at all, with the revs at just 1600 rpm.

What do you guys think?
Buy a new turbo? Or inspect the fuel System?

Thanks a lot for any help!
 
Some more info:

Injectors have never been removed or serviced in the last 4 years for sure

In August I had checked the water separator for the first time since launching in May. It was FULL of water (about half a liter). at this point I had asked my mechanic to service the engine again. New oil and filters. He said he did not find water in the engine fuel filter.
After some time I had checked the separator again and only found a small amount.

Today I checked it again before going out and found about 150ml. It seems like I have some water in my tank; or is this normal? I have to make it a point to check this at least once a month.

Sorry for all the text but I’m trying to post everything just in case something is relevant.
 
Someone with better knowledge than I will likely be along soon...but I’m half sure the kad32 might have an actuator on the turbo. Is that perhaps at fault ? Meaning the exhaust is being bypassed away from the turbo ? Defo sounds turbo related. Was originally thinking you have an exhaust leak perhaps, but black soot in the engine bay would be very obvious. A blockage in the exhaust would be unlikely too, given the VP doesn’t have flapper shutters in the exhaust
 
There is no actuator or wastegate or any type of control on the turbo to my knowledge.
My mechanic is eliminating any chances of intake leaks or exhaust blockages since the engine is working perfectly during supercharger operation (1700-2500 rpm)
 
There isn't a turbo actuator on a KAD32.

Start with the cheap fixes first: checking the fuel filters will tell you all you need to know about any possible diesel bug problem. They will either be clogged with black stuff and goo, or they won't.

Adding 180kg and hull/drive fouling is one issue. 180kg ... is that a typo? That's a huge amount of weight to have added.

But 10psi boost and revs cycling is a turbo issue.

If you remove the exhaust elbow and inspect the turbo, what do you see?
Is it free to turn with no play?
Is the housing corroded or water damaged - it's possible that the additional 180kg at the stern has raised the water level in the exhaust pipe.

Replacing the turbo more than once suggests that something is killing your turbo, and that needs to be fixed first before you just keep changing turbos.

I had about 1000hrs on a pair of KAD32's, all on the original turbos.
 
Last edited:
Water in the fuel is possibly entering the tank from the fuel filler cap not making a seal. Is an O ring seal on the filler cap missing?
Keep changing the primary and secondary fuel filters until the problem is resolved.
 
FlowerPower said:
Adding 180kg and hull/drive fouling is one issue. 180kg ... is that a typo? That's a huge amount of weight to have added.
Click to expand...

Sorry I checked again, I added 16 sheets of 4.9kgs each, so no more than 80 kgs.


Montemar said:
Silicone exhaust pipe has an internal collapse?
Click to expand...

I had this too after I started having problems. Lost all boost. I replaced all three with high quality multilayer silicone ones.
 
Hvae you checked the fuel pick up pipe in the tank as they some times have filter on the bottom of the pipe that goes in to the tank. I have had it were diesel bug had clogged this filter and i could not get correct amout of fuel delivery . I would check this first as thats the first point of the fuel line and you said you have changed the other filters.
 
fuel side would be my first check. As you say....no black smoke indicating air restriction. Could be as simple as the engine fuel filter sucking air
 
FARSCO said:
fuel side would be my first check. As you say....no black smoke indicating air restriction. Could be as simple as the engine fuel filter sucking air
Click to expand...

So how would fuel filter sucking air explain the boost dropping to 10 psi when the supercharger cuts out?
 
Given it is in a never ending cycle it is not fuel in my view. I can see it happening once and then repeating once stopped and the crud falls out but not over and over.

In my view is is turbo. Turbos are simple things. Exhaust in. It goes round.
If something is wrong it is either no exhaust, seized or the waste gate ( or whatever the current name is ) is open or the induction side has a massive leak but in that case it would not run normally on supercharger.
 
I'm suspecting a water damaged turbo.
But the root cause needs to be fixed as well, rather than swapping turbos once a season.
 
FlowerPower said:
So how would fuel filter sucking air explain the boost dropping to 10 psi when the supercharger cuts out?
Click to expand...

my instant thought was stuck turbo but it’s been checked. If it was fueling ok you’d get black smoke? Down on fuel down on exhaust hence the turbo isn’t spinning up enough to take over when the sc cuts out.

the fuel system has also been messed with but all was fine before.

more than ready to have the wrong end of the stick. Wouldn’t be the first time
 
waiting for someone more knowledgeable, my thoughts:

if exactly the same thing happens with the old (well 1yo) turbo as well as the recon one you fitted, I v.much doubt it can be the turbo itself, paraphernalia (which I've no idea what they are in this engine) could be.
Seems that you methodically have eliminated bit by bit.
My suggestion would be to try adding a vacuum gauge on the prefilter/waterseparators and see what they do when the revs climb there.

one engine or two, slipping bushes on duo props would they have similar symptoms on the wrong engine?

V.
 
Ohh loads IOM explanations here .

Without looking at the exhaust side of the turbo it’s hard to put a definite answer to the fault.
The fact there is 10 psi from the turbo after the Sc has cut out shows the turbo is giving something , however the fuel pump relies on positive manifold pressure to make it go into full fuel governor position , the lack of manifold pressure backs off the fuel as it’s not pressing the diaphragm in the top of the pump.
The linkage inside the pump can seize up if the boats been stood a while .
The turbo needs to be checked .
The air inlet pipe needs the o rings checking from the turbo to intercooler .
Lastly the Y connector inlet pipe has a flap valve , this can stick causing a blockage of air into the turbo .
 
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