KAD 44 compressor cutting in/out above 2500rpm

[novanta]

KAD 44 compressor cutting in/out above 2500rpm, VIDEO'S!

Picture this:

Princess V42, KAD 44. Engine's are running fine, compressors engaging at 1700rpm, boost is OK, stb compressor cutting out at 2600rpm, and then in/out/in/out. Port compressor cutting out around 3000rpm, no problems there.
Belts are OK, turbo's spinning free (I removed the elbow to have a look). I suspected the turbo but it seems in good condition. The compressor/turbo valve close to the airfilter works fine, I changed the manifold air temp. sender from port to stb, but problem is still there.

Next time I will have a look at the drives (maybe the exhaust is blocked with marine growth but they seem to be clean) and will check the tube underneath the computer (charge air pressure) for leakage.

The owner bought the boat last year in England, and it was serviced there. They even checked the valve clearance. The computer on the stb engine is new. I don't know why they changed it. The boat performed well last year untill a few weeks ago.

Who can help me on this one???

 

[DavidJ]

Can you easily swap the computers over? (and see if the problem swaps)
Very interesting that the stb computer was replaced, maybe worth contacting the previous owner.

 

[novanta]

Yes, I can change the computers from port to starboard. Maybe I can borrow a Vodia tool to check the computer.

Anyone else a good idea?

 

[aquatom]

Almost certainly a worn turbo. You need to check the clearance between the exhaust turbine and the housing any more than about 2mm and that will cause it.

They tend to showup more towards the end of the season when there is a bit of growth on the props.

 

[novanta]

OK, I only had a look at the inlet-side of the turbo. Not to much play at the bearing and it spins free.

With the Vodia tool I can read out the inlet pressure at WOT so I can see what is the problem...

Thanks for your help, I will keep you informed!

 

[aquatom]

Yes. When running the engine under load monitor the charge air preshure with the vodia or EDC key then slowly bring up the revs until the supercharger cuts out. If at this moment the charge air preshure drops then the turbo boost is not high enough

 

[novanta]

Update:

I had a Vodia tool but I could not make contact with the computer, don't know what I did wrong... Did not work on both engine's...

So, next day, returned to the boat with a ordinairy turbo pressure meter (from my Lancia Thema turbo) and made a few test runs.

As soon as the compressor cuts out, the pressure dropped because the worn turbo.

We made two video's of it, I will put the link here so you can see the difference.

 

[novanta]

The port engine:

http://www.youtube.com/watch?v=LCZ6QglpFs0



The engine with the worn turbo (microphone didn't like the noise...):

http://www.youtube.com/watch?v=dcOwWu26Kkc

You can see that when the compressor stops, the pressure drops under the 1 bar.


We ordered a new turbo!

 

[MarieK]

How many hours are on these engines?

 

[novanta]

Less than 1000 hours... Ninehundred-something....

 

[novanta]

Problem solved!

http://www.youtube.com/watch?v=wSAvovsU-uQ

We fitted a new turbo and did a full engine service including valve clearance. Some of them were 0.8 instead of 0.4mm...
I could not find anything wrong with the old turbo when I removed it so I got a bit worried, but with the new turbo the engine runs fine. Still, I can't see/feel any difference with the port turbo so maybe that one is at the end of it's life also...

Thanks everyone for your input!