I have a problem .... with a KAD 300 ---where are you Spannerman ?

RIMCOas01

RIMCOas01

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Did not post earlier as boat taken out/- tested for several hours by 2 (yes 2) VP service engineers on sep. days. They are stumped ... so now the post.

Toward the end of the season the boat started to have problems "getting it up" ... the revs I mean. Regularly serviced by the "pro's" ... now run 473 hrs, last full service with valves, etc at 428hrs.

Regardless of conditions, or hours of running .... when the revs drop below 800 I have to coax them up again to the normal 3400/- 38knot limit.
IE. Advancing the throttle increases the revs to ca. 1400 and then they just drop off. Slowly throttling up, backing off, up again, backing off again , etc, etc ... and then eventually at some point it seems the engine says " Oh, okay then ... here we go" ... and I am off.

And everything is perfect .... until I have reason to drop the revs below 1400 or so and the problem (and solution) is repeated.

2 VP engineers have had the boat out and cannot figure out the problem ... starts first time, filters and belts replaced earlier in the season and still okay, no water in either primary or secondary filters, no electronic faults diagnosed, no "blowing", no water ingress/- oil is clean, compression A1, injectors fine, hydraulics & cables fine, temperature readings fine, oil pressure fine, voltage fine, kompressor fine, ...

So ... what is the cause ... it's cost me already for their time ... without a solution being found.

PS . She is now high and dry having her bottom scrubbed ... neglible growth and outdrive mechanically A1

M

Apologies if post a bit long ...
 
I don't know anything specific to the KAD300 (or marine engines in general) but it sounds to me like one part of the electronic system for the engine isn't functioning correctly. just because it doesn't show a fault doesn't mean it isn't faulty, it just means it doesn't know it is faulty - if that makes sense.
 
Are the engines fully EDC or does it have an actuator that works a standard throttle linkage? If a standard linkage then a bit of string around it with engine hatch up pull string and see if boat performes correctly?
 
THANKS FOR VIEWS/- RESPONSES :

Fully EDC ... same problem with engine "hatch" up or down. Electronics have been checked with "meters" ... supposidely all the readings are within range.

I also feel it is an electronic problem ... but what electronic fault is it ... and how to find it ?

M

I, and the 2 engineers embarrasingly so are bl..dy stumped !
 
We had similar exceriences with our KAMD300's although with a clear reason. Round the same rpm engine cut off ~500 rpm for a second or so, then increased the revs again, cut off again and so on.

The reason was that engine was runnig too hot due to blocked raw water cooling, so the engine was trying to 'protect itself'.

I've also had bmw giving error messages on the display but showing nothing on the tester, so these fault-diagnostic -things work unless they are faulty /forums/images/graemlins/mad.gif

So unless any reason can be found for the ECU (engine control unit) to get input that something is physically wrong, it might be the ecu itself that is the problem. I don't know if it can be 'booted' or have the software updated but you might be looking at replacing it /forums/images/graemlins/frown.gif

I actually have no experience on ECU's so this is just guessing.
 
Hei ... 1 engine

Engine temperature checked .. okay ... problems persists throughout the temperature range, ie. starting from cold and even when run for several hours. ...

I feel it is "electrical" as the fault cannot be seen (if mechanical would expect something flapping, steaming, leaking, whatever). The fuel pump is okay as well (also replaced last season and checked)

I am no engineer but suggested to them that are it must be something do do with the widget not getting a signal/- electrical pulse from the whatsit.

They said I was of no help !

M
 
This is pure speculation on my part but my guess would be its something to do with the electronics/protection monitoring the mechanical compressor, supercharger. At low revs the supercharger clutches in and clutches out as rpm rise and boost is provided by the turbocharger. The supercharger is belt driven from the crankshaft and there is probably overspeed protection to stop engine rpm increasing if it is still clutched in. 1400rpm sounds strange though. I would have guessed it clutches in around 1000rpm and clutches out around 2000rpm. Anyhow my best guess is that the electronics that monitor engine speed and control the supercharger clutch are on the blink. Most likely the speed probe. Did I read somewhere it takes a reference from the alternator??? Is the alternator drive belt tensioned correctly???
 
Might be worth having a look HERE as it seems a similar problem. Might be worth the $25 to sign up so you can see what suggestions are given. May well be worth asking your won question.
 
I looked at the posting on boat diesel and he says,
"Directly switch the electro clutch for comprssor drive with external 14 VDC suply and yes is engages and stays that way"
Well it should not stay that way!!
At a given rpm it should declutch because the turbocharger provides the boost at higher rpm and the compressor (supercharger) should not be driven at higher rpm. Its there to provide boost pressure and so improve torque at lower power settings where the turbocharger is not operating at optimum speed. I still wonder if there is an overspeed protection to limmit engine rpm if the clutch does not disengage on rising rpm??
 
Thanks. I have never paid much attention to mine but at a guess I would have said it engages around 1200 rpm and out at 2200/2300rpm. It occurred to me that the newer higher output KAD300 engine might need the supercharger coming in a bit earlier. It has to declutch though or it would go bang at constant high revs so there is sure to be some sort of overspeed protection on the supercharger.
 
David,

I've never really consciously noted the supercharger rpm on my KAD300's, but in at 1200 and out at 2200 is about right. I reckon this could be a supercharger problem - without it, the revs would have to come up quite a bit before the turbo spools up.
 
Could it be supercharger problem?? On mine there is quite a bit of supercharger whine when it cuts in (approx 1200/1300rpm). Is it audible on yours? Without it, the power would fall off very quickly as the turbo spools down. Can't help but thing the VP guys would have found something as straightforward as that however.
 
Hi, Have you tried disconnecting the small black plastic pipe that goes into a T fitting on the underside if the ECU on the fuel filter, check that its not full of condensation and blow through it to make sure its clear, I have had a lot of these fill with water and they can give the symtons you have as the ECU doesn't feel the boost coming on from the compressor and doesn't increase the fuel delivery. If there is water present you may ultimately need a new ECU if the pressure sensor is damaged by water contamination, but try drying it out and check the blanking plug on the other side is tight and not leaking.
You say the compressor is fine, is it cutting in at around 1700rpm and out at around 2500rpm.
Does it couple in automatically when you first start from cold and let it idle, it should and then drop out when the engine reaches 60C.
Does it smoke when the revs fall off at 1400rpm, I am trying to work out if its not getting enough boost, or if its lack of fuel in which case it won't smoke.
 
Yes, could be, but the compressor is fairly basic. Rootes type blower I think. Mechanically driven so If its turning there cant be much not to work. Is there a waste gate type arrangement (bypass or pressure relief valve) after the compressor that could be opening I wonder??
 
Not seen this problem on this series of engine but have replaced many switches on the ecu of tamd74/75 series engines, dont suppose its an overheat problem from the edc temp switch, have the engines been read with the diagnostic key?
 
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