VP KAD series turbo's, how do I know if they've failed?

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A_8

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I took the boat out for a run last weekend and opened the throttles fully. To my surprise the boat was underperforming and the port engine was running at 100-150 rpm's lower then the other engine.
I figured it could be a fuel flow issue or the Turbo. The engines are now at 800h+ and I seem to remember there is a sort of consensus that these turbos may start to fail at around 1000h.

I know you can check the center axle in the Turbo, which I've done before but will that be sufficient, can the problem with the Turbo be more subtle and need other methods of checking?

Anyone know?

Thanks/
Michael
 
100-150 rpm doesn't sound enough to make a significant difference to the boats performance. My rev counters (KAD32s) generally show that sort of difference at WOT and I've never worried too much about it.
 
I agree with medreamer, unlikely to be the turbo. Maybe just a dirty fuel filter or maybe nothing at all.

A sign of the turbo going is black smoke where the engine is being over fueled due to not enough air.
 
The turbine side of the tubocharger does wear away due to the corrosive effect of exhaust gasses. If you remove the exaust elbow and check the clearance between the turbine blades and the turbine housing it should only be about 1 to 2mm.
I've just had my turbos replaced on my KAD 42's with 850 hours. The gap was about 6mm and the exhaust gasses were just bypassing the turbine. £1000 each!!

Eddie
 
Turbo smoke

A sign of the turbo going is black smoke where the engine is being over fuelled due to not enough air.

Just curious would you notice black smoke if you are on stern drives as the exhaust gasses will be under the water rather than on the surface.

Are there any other symptoms ,would the boat be slower getting the boat on the plane,would top end speed be a lot less than normal.
 
At this time of year, 150rpm down and a slight of loss of top speed is far more likely to be hull fouling / manky props rather than turbo failure or any exotic causes.

dv.
 
"The engines are now at 800h+ and I seem to remember there is a sort of consensus that these turbos may start to fail at around 1000h."

I would be very interested to know where that comment came from, I am at 1200hrs on my 2002 S28 from new and to date the turbo's have been not problem, a bit like my outdrives that are supposed to fall off at 1000hrs according to some people.

As FlowerPower has said it is more than likely to be the slime/growth on the bottom of your boat, that on it's own can easily take 5 knots off your top speed thereby reducing your top RPM.
 
VP are being very paranoid when they advise you to "exchange" your outdrives at 1000hrs. If they have never had water inside and keep shifting smoothly: keep trundling along!

Even if it starts to go clunky or delayed-shifty, replacing the cone clutch will usually keep it going for the same time again for less than megabucks.

dv.
 
Thanks all,

No visible black smoke and I've had the boat for 5 years and it has always done 36 knots, 4000 rpm's on both engines at the beginning of the season. 34-35 knots and 3850-3900 on both engines at the end of the season.
Now it only does 30-31 knots and one engine is down on rpm's so something is wrong.
As to other symptoms I have a feeling its not quite as fast on the plane as usual and I remember struggling to get both engines to "joint the same beat" a month ago or so.
My suspect is the turbo unit, partly because its behaving as usual at lower revs but also because the common view that they fail around this age.

/Michael
 
Also worth checking injectors: a KAD43 running on 5 and a half cylinders is not a happy KAD43. Serious injector failure (hosing) can cause major engine damage if left un-fixed.

dv.
 
zingaro said:
Just curious would you notice black smoke if you are on stern drives as the exhaust gasses will be under the water rather than on the surface.
Click to expand...

yes you will notice because they are hot and they are also gases and are not dissolved in the water so they will naturally rise through water and also because they are hot.
 
I have a very similar problem on one of my AD31s, but in my case it isn't due to slime or other fouling. At idle the engine vibrates much more than the other and it didn't at the start of the season :eek: So far eliminated the turbo, injectors and all filters, and it doesn't smoke any more or less than normal, hasn't burnt any oil or lost coolant. Next in line is the fuel injector pump..... With the cone clutch in one of the outdrives well and truly fried, I can feel a credit card melting bill heading my way soon :(:(
 
When a turbo went on one of VPs KADs on a Princess V39 I used to own, there was no way she'd get on the plane. Lots of black smoke, etc, etc.

Given the symptoms, I'd find it strange if it was a blown turbo, and agree with another poster that it is far more likely to be fouling on the hull or blades.
 
A couple of years ago I had a problem where one of my engines over a few months lost revs. Ended up with max revs around 3200 instead of the usual 3800-3900. I changed every filter there was, checked fuel lines the lot. The 'fault' turned out to be that on the end of the fuel pickups in my tank there is a fine wire gauze which over the years had got partially blocked. A quick wash in petrol cleaned the gause and it's been fine ever since.
 
We had a similar problem more than once. Each time it was one or two injectors out of tolerance and reshimming them fixed the problem. We have just had to have two injectors fitted with replacement nozzles as they were beyond adjustment, and as a result, they stripped the pump as well to see why we were losing so many injectors (8 in 4 years on the same engine). I'm still waiting to hear the full story from Col, but there were a couple of pump problems as well, apparently.
 
Thanks again,

I'll start by checking the fuel again, then the turbo axis for excessive movement.

For the injectors, are there any other symptoms i should look for?

For example, would there be more vibration, smoke or general lack of power through the rev range?

/Michael
 
Dont ignore fouling comments. We experience heavy fouling here in Sant Carles, 3 boats this year were about to have their turbos stripped/inspected, only to find out it was due to fouled props. Medskipper, an experienced sailor who knows his boat very well was one of them! Check it out first!
 
You are right, I was down at the boat yesterday and did not fancy checking the stuff I planned to.
I decided to start looking for other causes if I still had a problem after its been cleaned.
 
Again, reporting back on the actual cause for this. I have now lifted the boat and cleaned the hull, legs and props. The boat now tops at 36 knots and 4000 rpm's on both engines so no Turbo problems yet:)
 
just a note for future queries.. how are you reading the speed? I found most of my problem was the paddle wheel reading into the speedo.. the GPS actually gave the correct (higher) speed, so just reset the ST60 !
 
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