Advice regarding noise, power loss, overheat. KAD engine

Would you consider her to be over propped if she can still reach max RPM relatively easily once the engines and boat are fully on the plane. The boat left the factory with B5's on and previous C4's being the stainless steel rough equivalent. I must confess with B5's first on before this issue the boat felt much better. Appreciate that old engines may be getting a bit tired and may benefit from a lighter prop, but she did respond really well with the new props on both getting on the plane and at cruise before this incident. At the time I was quite delighted. Everything felt nice and tight
 
BruceK said:
Would you consider her to be over propped if she can still reach max RPM relatively easily once the engines and boat are fully on the plane.
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Ordinarily No .

This is the bottom of the diagnostic tree after checking and eliminating all the above posts ^^^ - sensible suggestions btw .
It’s not the -go to -first one - agree

But with duo props and aged engines I wonder if the “gospel “ reach rated rpm and not overheat ( water remember ) is open to interpretation and refinement ?

Maybe it’s suffered actual getting out of the hole ?
The EGTs movement are almost instant up and down not quit as quick a tachometer guage but very similiar .
Where as water and oil temp just slowly rise and fall .
Eg when I drop off the plane say throttle back they drop from 550 to under 300 in as long as it takes to move a pair a Morse sticks slowly back - say 5 seconds .
Same rate of movement when accelerating up too .
Mean while water temp lags behind taking minutes for any movement .


Just one more thing are these engines the OEM ? Factory fitted ?
 
Portofino said:
Just one more thing are these engines the OEM ? Factory fitted ?
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Yes, I have the build original documentation, drawings and build photos courtesy TAG Formula.
Formula boats do Volvo and Mercruiser diesel and Merc petrol and have mine have been maintained by a Volvo dealer for major servicing for the last 10 years. (Prior to this she was a Med boat)


I will go back to C4 reluctantly if necessary. Anode wear and the constant feeling of cruising in 3rd gear is what put me off them.
 
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Just another thought - have you checked for air leaks after the turbo compressor? might explain the buzzing noise if a gasket/seal has failed.
 
kashurst said:
Just another thought - have you checked for air leaks after the turbo compressor? might explain the buzzing noise if a gasket/seal has failed.
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No I haven't. But based on early feedback I will be inspecting this weekend. As for your earlier question about smoke. I cant answer for certain. I have this vid from a mate from last weekend that shows a wake shot coming out the channel. At that point the engines would still be climbing in rev range to get to full speed and so still under full throttle. Seems clear to me? ...

https://gopro.com/v/mgLd9JBay7o8
 
I have a similar issue and think I may have found the cause - a clamp on a hose between supercharger and turbo was slightly loose with a very slight oily mark on the metal tube . I have yet to test whether this has solved the problem.
 
Well the exhaust elbow is not corroded closed by any means. In fact apart from rust at the flanges looks in perfect order.

Visually, trying to squeeze in the turbo looks reasonable albeit sooty because of all the displacement speeds I am doing. However photo seems to tell another story though the discrepancy is such I wonder if the photo has shadow.
https://imgur.com/DpWBTv0.jpg

All pipes are in good order and I cant see any leakage

So I still havent discovered the overheat problem nor it being gutless.

I will change impellor and thermostats next though they too test and look fine
 
Danfarry said:
Bruce, no expert but that turbo looks very very sooty. I have seen a completely seized/blocked turbo that looked like that. It was on a yanmar engine in a sailing boat.
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It turns very smoothly Dan. Bearings or bushes in v good condition. Because of the overheat issue I have been doing a lot of displacement speeds. Last trip back was displacement for 2 hours. I expect it to be a bit sooty

Its the blades I question.
 
BruceK said:
Well the exhaust elbow is not corroded closed by any means. In fact apart from rust at the flanges looks in perfect order.

Visually, trying to squeeze in the turbo looks reasonable albeit sooty because of all the displacement speeds I am doing. However photo seems to tell another story though the discrepancy is such I wonder if the photo has shadow.
https://imgur.com/DpWBTv0.jpg

All pipes are in good order and I cant see any leakage

So I still havent discovered the overheat problem nor it being gutless.

I will change impellor and thermostats next though they too test and look fine
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Bruce, have you seen this video?

https://www.youtube.com/watch?v=PVahlajXTdk

From my phone your turbo looks OK compared to the knackered on in the video.
 
95F3C633-3106-4B41-96ED-68F22A9C477A.jpeg

Just replaced with new on my just purchased boat.

FCB77907-8E4C-4B17-A656-18A44C270524.jpeg

Elbow wasn’t much better :)

KAD42a aswell. Still down on revs but I’ve yet to investigate.....or even have a run on her personally!
 
FARSCO said:
View attachment 72082

Just replaced with new on my just purchased boat.

View attachment 72083

Elbow wasn’t much better :)

KAD42a aswell. Still down on revs but I’ve yet to investigate.....or even have a run on her personally!
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Yes, mine were both in far better condition. I replaced the elbow anyway but my blade tips arent worn nearly as much.

DpWBTv0.jpg


I have removed the thermostats altogether for a test because the "kit" advertised was not a kit. It was a single thermostat and ring instead of two of each and a gasket. Mightily peeved over that. Replaced the impeller though I could see nothing wrong. If this doesn't work it's either barnacles in the legs causing restricted intake or excessive exhaust back pressure or I have something seriously wrong with the engine. :(

Tomorrow I test. We shall see.
 
kashurst said:
first thing is sort the over heating - change the impeller - the core may have spun out so will look OK but not be very good, blockages in pick up pipe, carp in the leg opening - what is the water flow like in the raw water filter?
I don't think your cooling system is completely clear - its pretty hot in the UK at the moment but what is the sea temp? I'm in the med with kamd 300s with seawater at 30 degrees and I'm seeing @ 84 degs at 3300rpm
get an infra red handheld thermometer and start measuring temps on both engines - thermostat housing, cylinder head, heat ex-changer inlet and outlet pipes, exhaust elbow near where the cooling water goes in, see what differences you get.
Take the exhaust elbow off and have a good look inside and check the stainless insert at the turbo end for pin holes.

second thing midrange grunt- don't think it's the turbo as you can get max revs under load. don't think its fuel blockage for the same reason. If turbo was knackered you wouldn't get max revs and you would get the hunting on and off the supercharger behaviour. The lack of mid-range grunt sounds like a supercharger issue. Is the clutch on its way out and slipping? Or is the clutch coil going with a bad contact developing internally? I'm thinking electrical problem with supercharger as its just started out of nowhere. Turbos fade away.
Get someone else to drive and watch the supercharger clutch as it engages and disengages - look for sparks. is it intermittently stopping and starting?
try disconnecting the electrical supply to the supercharger and see if it gets worse or stays the same. (don't think KAD 42 ECU will notice). If you have a multimeter measure the resistance of the clutch coil - I think it should be about 4 to 5 ohms
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Clever begga! You know I pulled the impeller and checked. Core looked absolutely fine. Blades perfect. Nothing wrong with it at all. Took the boat out and the overheating was even worse. In for a penny in for a pound. I had already spent over 300 quid changing parts whats another impeller? So anchored up out side the channel and changed it in an act of desperation. Youll remember I removed the thermostats because I didnt receive a whole kit. Now the engine runs too cold. So will be putting thevold back in.
Im looking at this old impeller. Absolutely nothing wrong with it that is visible. Tried turning the core. It aint budging. Go figure. Must be spun but you'd never guess if I gave it to you....???
 
I guess you can’t put the same forces on the impeller by hand that the engine does.

Great result!!

Have you found the missing revs?
 
Yes. I removed all intake rubber joints to inspect. Nothing amiss found but now I notice the rubber manifold just after the super charger blows up at least half its girth again when the super charger kicks in. Quite alarmingly so. It looks like it wants to pop from the pressure. Never seen that before so one of the rubber manifold joints must have been leaking. That whumpf of the back pressure slamming the bypass flap closed is also back when you come off the throttles. So all is good.
 
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