Sooty kad32

[Wobbo]

I'm leaving a layer of soot on the water. After doing 5kt up the river for 5mins or so just before increasing revs there's a layer of black soot on the water. On start up there's a cloud of grey smoke and after that it's ok. Running at speed it's good. Guessing it's unburnt fuel but how is it fixed!? All filters are new all oils are new all belts are new.

 

[Momac]

Has this started since the oil and filters were changed ?
Could a little too much oil in the engine cause this issue?

 

[Beamishken]

Is the kad the one with the solenoid operated flap in the exhaust to help with cold running smoke? Could be a fault with the flap or actuator (if its fitted to that model)

 

[Wobbo]

Oil levels good, it's always been a bit sooty. I think it's unburnt fuel so I guess I'm getting to much fuel or not enough air!? Or something else altogether!

 

[scottie]

Oil levels good, it's always been a bit sooty. I think it's unburnt fuel so I guess I'm getting to much fuel or not enough air!? Or something else altogether!

Where is the throttle at startup?

 

[Wobbo]

Is the kad the one with the solenoid operated flap in the exhaust to help with cold running smoke? Could be a fault with the flap or actuator (if its fitted to that model)

Hmmm..not sure. I'd say not but I shall have a look into it ta

 

[scottie]

Is the kad the one with the solenoid operated flap in the exhaust to help with cold running smoke? Could be a fault with the flap or actuator (if its fitted to that model)

Is that not the 30&40s

 

[Momac]

it's always been a bit sooty. I think it's unburnt fuel so I guess I'm getting to much fuel or not enough air!?

When you say 'always' ... what period of time and hours run is that?
I have heard of smoke issues being caused by dirty fuel and cured by adding fresh fuel.

 

[QBhoy]

These are normally very clean efficient burning things. The low rpm supercharger seems to that. Making sure that there is enough air to burn the fuel given at low rpm. Then the turbo takes over further up the rpm.
I’d suspect either your supercharged isn’t doing it’s job, or you have a leaking injector or two.
Only other slight cause might be if you aren’t getting up to efficient running temps by means of perhaps a stuck open thermostat stat ?

 

[Momac]

I do a lot of river hours without the supercharger cutting in at all and the engines don't smoke excessively. The engine will get up to 80 degrees which is the thermostat temperature - but no higher. A few whisps of smoke are noticeable when idling in a lock but not an issue. certainly not leaving a trail of soot on the water. So I don't think the supercharger comes into it.

Could be a stuck open thermostat (there are two on the kad32) if the temperature remains low at 1400rpm (below supercharger cut in) on the river . If not , as said , perhaps injectors need attention.

If no temperature issues I would suggest trying a fuel additive and give the boat plenty of use. If that does nothing perhaps then look at injectors.

 

[QBhoy]

So I don't think the supercharger comes into it.

Suppose it would come into it...if it wasn’t working. That’s what I meant really.

Good luck.

 

[Momac]

So I don't think the supercharger comes into it.

Suppose it would come into it...if it wasn’t working. That’s what I meant really.
.

On the kad32 at under 1500rpm the supercharger should not be operating .

 

[Wobbo]

Where is the throttle at startup?

Only just open on cold, nice warm day it doesn't need any

 

[Wobbo]

My old laptop finally gave up and was having ballache logging in on the phone but im back in again so i will give an update on this sooty problem i had.
After much head scratching i by chance bumped into a Volvo Penta engineer in the pub!!! Long story short, if your props are not in tip top condition or you are running the wrong props youll have problems. We had dinged our A5 props and taken knicks out here and there over time but had to change when a blade broke off. The sooting issue had started probably when the first dings had started to appear and got progressivley worse. We had a spare set of A6s, not that great but good enough we thought but it really made the problem worse. Much worse.
A5s are what the boat is set up to run with so after buying new ones i would describe the differance as running your car with half inflated bald tyres for weeks and then jumping in with nice new ones.
It is literally like a new boat.

 

[stelican]

I had a similar problem (black carbon trail in water) on a AQ31non supercharged it was caused by a sticky turbo not spinning up.
Usually happen when boat layed idle for a long period.

 

[Greg2]

My old laptop finally gave up and was having ballache logging in on the phone but im back in again so i will give an update on this sooty problem i had.
After much head scratching i by chance bumped into a Volvo Penta engineer in the pub!!! Long story short, if your props are not in tip top condition or you are running the wrong props youll have problems. We had dinged our A5 props and taken knicks out here and there over time but had to change when a blade broke off. The sooting issue had started probably when the first dings had started to appear and got progressivley worse. We had a spare set of A6s, not that great but good enough we thought but it really made the problem worse. Much worse.
A5s are what the boat is set up to run with so after buying new ones i would describe the differance as running your car with half inflated bald tyres for weeks and then jumping in with nice new ones.
It is literally like a new boat.

Well that is helpful to know - never heard of it before and wouldnt have thought about it as a possible cause. Thanks for updating