KAD43 Strange noise...new turbo required?

[JumboTed]

Hi all,

I have a strange noise coming from one of my KAD43 engines. It started to occur not long after receiving the boat after maybe 2 hours we were at 3000rpm and I noticed the RPM drop maybe 200 and then recovered again.

I thought it was an air leak (as did local penta engineer) because it happens as soon as the supercharger kicks in. I found a small hole in the hose that connects the turbo pipe and supercharger ducting but replacing this has made no difference. I had a good feel around the engine and can not find any other air leaks but the strange noise sounds like it is coming from the turbo when I have my head next to it.

here is a link to the noise -

I have had the CAC and turbo off already and put in new seals/gaskets here is what the turbo looked like. -

Has anyone ever experienced a noise like this from a failing turbo? I know its hard to tell with the supercharger noise at the same time. Also what are recommendations regarding new turbo or getting this one refurbed? Any ideas what would have caused the turbo to fail? I would like to rectify and potential problems before i put a new unit on.

Many thanks for all help!

 

[simonfraser]

sounds like the supercharger running to me
the turbo and the supercharger should not be running at the same time as far as a know

 

[DavidJ]

Agree
I have KAD43’s and It’s the supercharger kicking in. From memory it comes in at 1800rpm and cuts out at 2100 ( again from memory). you may not hear the cut out so clearly because of engine noise.
The noise is not related to the problem. Maybe there is another noise that we are not picking up from your video. Your Volvo technician would know the supercharger sound.
Hope this helps

 

[[2068]]

If it sounds like an air leak, it probably is an air leak.

Check the air pipe connections again, and there's also a flap / non-return valve near the air filter that's worth a check.

Part 11 on the diagram
Volvo Penta Intake and Exhaust System | Turbocharger and Air Filter: A KAD43P-A, KAMD43P, KAMD43P-A, KAMD43P-B | Volvopentashop.com

 

[JumboTed]

Thanks will check all the ducting again, does the supercharger not supply the air for the turbo to run at low rpm, therefore when the supercharger engages the turbo will spin up as a result?

 

[DavidJ]

re What makes a turbo fail?
The housing and the blades corrode, not so much with use but just exposure to the salt water environment just a foot away.
I replaced both (with new ones) a couple of years back after having a similar RPM drop off and recovery as you are experiencing.
To be honest yours don’t look too bad....await more experienced replies than mine.

 

[DavidJ]

Thanks will check all the ducting again, does the supercharger not supply the air for the turbo to run at low rpm, therefore when the supercharger engages the turbo will spin up as a result?

The turbo is driven from exhaust gasses so is independent from the supercharger

 

[[2068]]

Thanks will check all the ducting again, does the supercharger not supply the air for the turbo to run at low rpm, therefore when the supercharger engages the turbo will spin up as a result?

The turbo will be spinning at low speed when the supercharger is running, it will be fully spooled up by the time it cuts out. Turbo is driven by the exhaust.

 

[DavidJ]

If it sounds like an air leak, it probably is an air leak.

Check the air pipe connections again, and there's also a flap / non-return valve near the air filter that's worth a check.

Part 11 on the diagram
Volvo Penta Intake and Exhaust System | Turbocharger and Air Filter: A KAD43P-A, KAMD43P, KAMD43P-A, KAMD43P-B | Volvopentashop.com

That’s interesting FlowerPower
Do the non- return valves leak through age/wear?

 

[[2068]]

That’s interesting FlowerPower
Do the non- return valves leak through age/wear?

Worth a check that it's not stuck or damaged.

 

[BruceK]

That’s interesting FlowerPower
Do the non- return valves leak through age/wear?

No but they can get stuck / sticky. Easiest way to find out if they are functioning is to hear that whumpff they make with the change in air intake as the SC engages/disengages at arount 2400 rpm


I dont hear anything unusual. The Supercharger at low revs always has that horrible growl that sounds like a card stuck in a bicycle's wheel spokes. You dont really hear that in normal operation as you power through that rev range quite quickly. I dont see or hear anything unusual from the video.

 

[JumboTed]

Yea wasn't sure how great it would come through on video, it does sound a lot different from the other engine which sounds like what my kad32 sounded like when the supercharger engaged. I'll check the non return valve. Thanks.

 

[volvopaul]

sounds like the supercharger running to me
the turbo and the supercharger should not be running at the same time as far as a know

The turbo spins all the time , s c. Cuts in and out when it’s told

 

[volvopaul]

Sounds ok to me , the turbo is in good condition looking at the video of the exhaust fan

 

[JumboTed]

Think I have a leak around the turbo gasket but it's a new gasket and seems right. Any ideas?

 

[JumboTed]

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!

 

[BruceK]

Why sir. I do believe that's belt slip. But not necessarily on the belt to the supercharger, the belt from the flywheel to the waterpump/SC drive pulley could also be the culprit. It will slip once the SC cuts in and the noise it makes will scare the bejeesus out of you.

Edit. Look for the telltale belt wobble. If they wobble there's a problem

 

[BruceK]

That whumph sound eg at 13 seconds and at end, is not the supercharger kicking in that's the non return flap. It's pronably vibrating itself with the SC not blowing consistently because of the belt slip. Not sure how your local Volvo dealer missed that. It's a common enough occurence when the boat has sat for a while especially if the pulleys have a crown of flash rust on them that's also now embedded itself into the belt.

 

[DavidJ]

Belts can sometimes appear tight but the “taper” can be worn and in consequence the “grip” is only taken by the bottom “flat” which is not enough to avoid slip.
3 words in inverted commas in the same sentence is record for me

 

[Momac]

Another suggestion . Could a belt tensioner be worn / faulty.