HELP KAD 43 revs to 2600 then drops

DavidJ

DavidJ

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Hi
First time out this season. Clean bottom and props.
Open up both engines (KAD43’s) and all ok to 2600 rpm on the starboard side then sudden drop down to 2200. I shut it right down then. Repeated same problem 4 times before turning back.
Back in marina and the motor spins up to 3000 plus with no problems
Brand new turbos 2 years ago.
HELP please!
 
DavidJ said:
Hi
First time out this season. Clean bottom and props.
Open up both engines (KAD43’s) and all ok to 2600 rpm on the starboard side then sudden drop down to 2200. I shut it right down then. Repeated same problem 4 times before turning back.
Back in marina and the motor spins up to 3000 plus with no problems
Brand new turbos 2 years ago.
HELP please!
Click to expand...

Could be restriced fuel flow? Check filters and fuel lines.
 
Are you sure the revs are actually dropping?
Could just be the rev counter or alternator giving incorrect readings, seems strange that the revs would actually suddenly drop rather than just stop increasing.
 
I'd agree, fuel restriction or air in the fuel system. Is it a hard start? If so check for air leaks specifically round the filters. Check for blockages in the lines (does the fuel flow freely and copiously when you release the filters.)
 
DavidJ said:
Hi
First time out this season. Clean bottom and props.
Open up both engines (KAD43’s) and all ok to 2600 rpm on the starboard side then sudden drop down to 2200. I shut it right down then. Repeated same problem 4 times before turning back.
Back in marina and the motor spins up to 3000 plus with no problems
Brand new turbos 2 years ago.
HELP please!
Click to expand...

Revving in neutral tells you nothing .

Sounds like the turbo is seized up as it’s running on boost from the SC then SC cuts out when turbo should cut in with adequate boost . Check the turbo spins .
 
volvopaul said:
Revving in neutral tells you nothing .

Sounds like the turbo is seized up as it’s running on boost from the SC then SC cuts out when turbo should cut in with adequate boost . Check the turbo spins .
Click to expand...

Thanks to all
Just checked the turbo and it spins freely. I like the logic and wonder if I unfroze it when free reving in nuetral. Filter shops closed til 4pm (Spain)
 
Hi FARSCO
A couple of months ago I bought your m/c tyre pressure monitor and have just fitted it (after the problem I’ll hasten to add)
Unfortunately at the moment just in the marina I’m getting. 00 reading. I’ll test it on my car valve maybe the sender battery has gone.
Incidently I removed the inner valve from the adapter. I don’t think it makes any difference.
Cheers
David
 
If it’s reading 00 then the sender is talking to the display...defo is if the sender temp is displayed.

There is a slight delay and I havent seen any meaningful readings until under load.

A good trick volvopaul told me is to put a screwdriver on the kick down microswitch located on the injection pump whilst at tickover. This will bring in the supercharger so you can check all the pipwork/cac for air leaks. That’s for a Kad42 though...I’m guessing it’s the same for a 43
 
Thanks FARSCO
Yes I’m getting a temp reading so must be working
The 43 is different that it has a little bit of electronics which senses speed and switches the SC in and out.
Just got windy again here so can’t test out. Still no solid cause of problem yet
 
Ah all is well
Took the boat out this evening and everything worked ok.
My guess is that the turbo had stuck and unstuck itself after a bit of a warm up. It’s the only explanation I can think of.
Anyway I’ll change the fuel filters tomorrow.
Thank you all so much for suggestions and support.
Good end to a really depressing day.
 
Good news :encouragement:

Think I said this before on the thread that mentioned winter storage in a hanger .
I think PeteM raised the question .

It may be relevant here ?
I returned to the boat in Jan after approx a 6 week gap .
Before firing up the engines I needed to sus out a possible future valve adjustment job .In curiosity I removed one of the 12 rocker box covers for a look.
Everything was basically bone dry in there as if it had never seen any oil !
When we did the job in May we removed the rocker box covers after only 3 days from a previous engine start , everything was dripping in oil so much so we had to place rags to contain the drips seepage .Feeler gauge needed wiping after every insertion.
Where as in Jan it was bone dry between the rocker tip and the top of the valve stem .

So imagine In frequent use over a long winter lay up exactly how dry can they get ? ——- turbo bearings and such like with lack of use ?

We now have an answer .

I know with some generators the engines stop with open exhaust valves inches away from the salt water wet elbows and develop a surface rust that ends up with pitting leading to a rebuild.

Starting to feel with boat mechanicals in salty environments it’s a case of
“ use it or risk loosing it earlier than expected “

There are manufacturers text book winter lay up procedures in every manual.
With this they would say remove the air filter spray fogging agent and tape up from outside air .Possibly drain the seasons used oil and refill with another agent and hand turn the engine to spread it about ( get to the bearings etc ) + much more ++++ .Theres a reverse recommissioning procedure next spring .

Buy how many actually do that ?

Do most just switch off say in Oct never run them and return in April / May ?

As you know I run my systems up regularly over the winter .

I know from cars particularly twin overhead cam engines the cam oil seals dry up irreversibly shrink and start leaking next time you start , if the thing is turned into a garage queen and not run over the winter .

I,am trying unsuccessfully to justify not regularly running them .
 
I think we all know the best thing to do would be to use the boat regularly and all year .
However that is often not what we do in practice.
I leave the engine alone rather than run it under no load.
 
MartynG said:
I leave the engine alone rather than run it under no load.
Click to expand...

+1 for me.

Question for Porto and others, when you rebuild a car engine you turn it over on the starter motor without letting it fire up until you have good oil pressure. I could easily do that on my boat by disconnecting the Seafire cable.

Would this be a good practice?
 
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