KAD43 Strange noise...new turbo required?

[JumboTed]

Okay, I've just changed all the belts and to my knowledge they are all tensioned correctly but will check all of them and tensioners. Would this noise not be heard all the time. Would this explain a lack of performance. Last time the engine ran under load I could only achieve 2600rpm.

 

[JumboTed]

So I've just realised the noise in the video of the supercharger engaging and disengaging is actually my friend on the throttle. It's the actual supercharger noise I'm refering to. Does it sound normal when the supercharger is running?

 

[A_8]

If the SC cant charge the air it might explain the 2600 limit. Have you checked if the SC actually delivers air pressure?

 

[A_8]

It sounds a bit too whiny so to speak even though it would be similarish as far as I remember.

 

[Momac]

For comparison what does the other engine sound like?

 

[JumboTed]

Will get a video of it shortly

 

[alt]

Sounds fine to me. KAD43 doesn't have a silencer IIRC, therefore the supercharger is loud. The KAD300 is noticeably quieter.

Maybe you can hear an underlying noise in real life, but I can't hear anything odd in the video.

 

[DavidJ]

Would this explain a lack of performance. Last time the engine ran under load I could only achieve 2600rpm.

is this 2600 on both engines or 2600 on one and ????? On the other?

 

[JumboTed]

2600 with both engines going on the plane. The other engine will reach 3900.

 

[A_8]

2600 with both engines going on the plane. The other engine will reach 3900.

Hmm, that is odd. The other engine should not get to 3900 unless the other is there as well. Are you sure the 2600rpm is correct?

 

[JumboTed]

Well sorry the 3900 was achieved when the bad engine was pushing maybe 3300. Since then it's max has dropped to around 2600-2800. It may achieve 3000 for a really short time and then the revs come back.

 

[[2068]]

Definitely double-check the condition of that smaller belt that drives the water pump and pulley from the crankshaft damper.

 

[A_8]

Well sorry the 3900 was achieved when the bad engine was pushing maybe 3300. Since then it's max has dropped to around 2600-2800. It may achieve 3000 for a really short time and then the revs come back.

Has the top speed changed with the 3300 to 2600-2800?
Even if the "bad" engine only got to 3300 the good one should not reach 3900.

 

[[2068]]

Has the top speed changed with the 3300 to 2600-2800?
Even if the "bad" engine only got to 3300 the good one should not reach 3900.

It might do if the belt is slipping at higher revs and generating a false low rpm reading from the alternator.

This all feels a bit trial and error,

A good engineer would be able to home in on the actual problem faster.

 

[DavidJ]

Okay, I've just changed all the belts

Sorry to be pedantic but is the problem still there after the new belts?

 

[BruceK]

It's belt. There may be another noise that is not apparent on the video but on that last one, belt for sure if nothing else is adding to the problem. The OP said he did belts recently. It's almost a certainty. How often have you nipped a new belt up and you have to redo it within the first day out. For me it's one of the engines every other spring launch. The tensioner pulley rear star gear gets crud and belt dust in it. The belts need the tension generated by the SC for them to settle that lot in.

 

[A_8]

It might do if the belt is slipping at higher revs and generating a false low rpm reading from the alternator.

This all feels a bit trial and error,

A good engineer would be able to home in on the actual problem faster.

Agreed which was why I asked about speed.

 

[BruceK]

Is this the same engine you just did the water pump on?

 

[JumboTed]

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.

 

[BruceK]

To my ear

this is untensioned belt

This is normal