KAD43 Strange noise...new turbo required?

[A_8]

So i'm afraid I may have wasted everyone's time. Here is a video I just took of the engine running at 1600rpm. Does it sound normal to you? -

The problem I have had is the boat is out of the water now at my yard. So i can't take it out to test. The last trip there was a horrible noise when the supercharger engaged like air leaking and the boat failed to maintain revs on the strbd engine. As I explained before the revs would drop during cruise until it would only maintain 2600rpm and I had to limp home with the other engine pulling us along.
Since then I have done a lot of work to the engine, I started on the strbd because I thought it required the most work. I flushed coolant, changed oil, all filters, all belts, cleaned the cac and replaced every seal I could think off between supercharger, and turbo and turbo to CAC etc and the hose on top of the engine from the supercharger to turbo. SO when I started the engine yesterday I was sure it sounded the same as before....confirmation bias? Stupidly I do not have a video of what it did sound like before I carried out the work.

However I went out and fired up the port engine and it sounded similar, and then fired up the starboard and this is how it sounded. I haven't changed anything on the port except for supercharger oil which I did while I was changing the starboard. So if this sounds normal to you please let me know. I can rest easy until she goes into water in April.

oh and sorry for wasting everyone's time if that is the case, i'm very greatful for all the help I have received on here.

This sounds normal to me and I agree with BruceK it's not uncommon one had do re tighten the belts.

 

[PowerYachtBlog]

Sounds pretty normal to me, unless it is doing the Supercharger automatic.

Supercharger kicks in at 15/600 and cuts out at 24/500. Turbo is always running in reality in these engines, but it does not start to boost before 2600.

 

[TK Blue MAX]

Hasn't someone else had this problem with mismatched revs ,one engine losing revs and the other increasing, turned out to be slipping props, diagnosed by jimmy the builder if i recall. Video of engines rarely gives a true impression of what the person recording hears in my experience.

 

[Momac]

I had a mismatched revs issue due ti my own fault........ fitted the wrong props one leg !
As a result one engine was working harder than the other.

I also recall a fault reported with failed bushes causing prop slip. I guess damaged props could have a similar effect.

 

[JumboTed]

Yes, i saw the thread on the slipping prop. When I increase revs on it and leave the other engine I do get a speed increase. Would this happen if the prop was slipping?

 

[BruceK]

Possible yes but it will get worse.

In my experience mismatched revs most commonly comes down to an alternator change and not keeping or replacing the original alternator pulley. They may look the same size but a small diameter difference could add up to 200 rpm at 3k leaving one engine leading rather hard. I noticed this with a disparity in fuel consumption between the two engines it was quite marked. Also on these analogue engines the tacho is always a suspect area too. I routinely check the tacho against a handheld unit.

 

[DavidJ]

Yes, i saw the thread on the slipping prop. When I increase revs on it and leave the other engine I do get a speed increase. Would this happen if the prop was slipping?

I had the rubber go on a prop of and earlier single prop boat and it was more like a clutch going on a car. Very obvious, lots of revs and getting nowhere. You don’t have that problem
Interesting point from BruceK. I changed an alternator last year with new pulley. I will check against a handheld unit.

 

[A_8]

So this the noise I have. I have checked for air leaks and tightened anything suspicious but all seems good. here is a link to the noise from in the bilge-

Definitely a different sound to the other good engine and the KAD32 I had previous. Any ideas what it could be, my next step is to swap the supercharger from the good engine and see if it still happens.

Thanks again for all help so far!

I can't help recognise this sound but don't remember the details but it might very well be an air leak and what you hear is the "non contained sound" from the SC. I am back to one my my earlier questions, have you checked there is actual air pressure from the SC? I have a very faint recollection that at some point I had something between the SC and engine air inlet come loose after some work being done.

 

[A_8]

Another thing, even if the SC is not working an otherwise healthy engine would very likely still reach full revs even though it would take some time. For reference and on my old Prestige 34 with 2 KAD43 and both SC disconnected the boat would eventually reach full rpm and speed.

 

[jon and michie]

Is there any updates ??

 

[JumboTed]

Hi, Sorry for the delay/

No updates yet. I will have to wait to see how she runs when I get the boat back in the water in April. Will keep you posted.

Thanks

 

[robertnicholas]

Hello all, new to the group. I have twin KAD43P after a full serive to both engines which are new to me. I had the same or similar sound in my port engine, the engine would then set off the relay, the engine still runs but I have no dash working at the helm and could not turn the engine off without resetting the relay in the little black box, I have noticed the alternator belt was lose and the voltage was at 12.5 volts to 13 volts bit the starboard engine was running at 14 volts, , any feedback would be very grateful

 

[DavidJ]

I’ve got KAD43’s and just picking one of your points, the ‘relay‘ you call it. I had a short in the supercharger wiring which caused the ‘relay’ to trip and I couldn’t switch the engine off. I couldn’t reset the ‘relay’ because of the permanent short.

 

[robertnicholas]

I’ve got KAD43’s and just picking one of your points, the ‘relay‘ you call it. I had a short in the supercharger wiring which caused the ‘relay’ to trip and I couldn’t switch the engine off. I couldn’t reset the ‘relay’ because of the permanent short.

Thank you, as soon as it trips the engine changes tone, I did have a hunch it could be there, is it an easy fix?

 

[DavidJ]

Thank you, as soon as it trips the engine changes tone, I did have a hunch it could be there, is it an easy fix?

For me I had to buy one of these but of course may not be the problem you’ve got therefore not the solution
See if you can find the specified coil resistance and check before you fork out cash.
23285069 CLUTCH - En-Gen Diesel Products Online Shop
Easy to fit if you have a decent set of circlip pliers. The set comes with shims to get the correct gap.
I edit
second thoughts
No need to check the resistance just check for short circuit. If it’s short circuited then that’s what it is and unless an obvious fix then get a new one.

 

[robertnicholas]

For me I had to buy one of these but of course may not be the problem you’ve got therefore not the solution
See if you can find the specified coil resistance and check before you fork out cash.
23285069 CLUTCH - En-Gen Diesel Products Online Shop

Will do thank you

 

[DavidJ]

Will do thank you

I’m hoping you get some more contributions on this one. I’m no expert just recounting my bit of experience.

 

[A_8]

Can't say I remember any relays tripping, there was a fuse iirc and -yes the clutch can go bad and short to ground but as DavidJ says it's easy to check.

 

[DavidJ]

Can't say I remember any relays tripping, there was a fuse iirc and -yes the clutch can go bad and short to ground but as DavidJ says it's easy to check.

Actually “short to ground” is more likely than the “short circuit” I mentioned.
Good point
and yes there is a resettable fuse not a resettable relay