Volvo KAD 32 Screaming Turbo's

[Ian Brown]

Recenlty purchased two new complete Volvo KAD 32 Compressor Turbo's as my old one's made such a high screaming noise when they kick in at 2000rpm. Having replaced them with new ones at £488 for the pair.

I have exactly the same problem with them screaming a high pitched noise like metal on metal. Can anyone help with some advise?

Regards

Ian

[doggypaddle]

have you checked for air leaks in the manifolds and pipework? turbo air leaks can reall scream.
a tip to find air leaks in turbo pipework is to spray an aerosol around the joins when the engine is idling, the engine note will change when the aerosol gets sucked in. you can use easystart, but be careful to keep the area well ventilated, and keep it away from the air intake as it will give a false indication!
check all the high pressure pipework from the turbo to the manifold and dont forget the compensator pipes and head to manifold gaskets.
it can help to restrict the air intake a bit with your hand too so there is more suck!

failing that get some to drive the boat with the engine hatch open and use a pipe as a stethescope to source the noise best done on a calm day!. when doing this its best not to get the pipe tangled in the alternator belt!
its unlikely to be the turbos if you have replaced them.

of course it could be something completley different

[ian parkes]

Where's Bob
I can't remember what its for but --
There is a small centrifugal governer on the top left of the engine that kicks in and makes a noise something like you describe . If you watch the engine as it revs up you can't miss it .

Maybe you have seen this but your description sounds just like it . Bob and I wondered what the noise was on his boat

[Searider]

Have you replaced the compressors (belt driven) or the turbos (bolted onto the exhausts)?

The compressors are normally pretty noisy, and it's not a pleasant noise either, almost like a gear whine.
The electric clutch on the compressor will screach a bit when it engages and there might also be a bit of belt slip. Does the noise go away once you go above 2800/3000 rpm?

Turbos should only give a bit of a whistle, although could be a bit of a screech if you have your ear close to the intake.

[ian parkes]

Originally Posted by Searider

Have you replaced the compressors (belt driven) or the turbos (bolted onto the exhausts)?

The compressors are normally pretty noisy, and it's not a pleasant noise either, almost like a gear whine.
The electric clutch on the compressor will screach a bit when it engages and there might also be a bit of belt slip. Does the noise go away once you go above 2800/3000 rpm?

Turbos should only give a bit of a whistle, although could be a bit of a screech if you have your ear close to the intake.

That guvernor I am on about is on the compressor pulley , its the top belt

[jwalker]

Originally Posted by doggypaddle

...a tip to find air leaks in turbo pipework is to spray an aerosol around the joins when the engine is idling, the engine note will change when the aerosol gets sucked in.... it can help to restrict the air intake a bit with your hand too so there is more suck!...

Except that manifold pipework after the turbo charger is pressurised by the turbo compressor so any leaks are outward.

[jwalker]

Originally Posted by ian parkes

That guvernor I am on about is on the compressor pulley , its the top belt

That's not a governor, it's a clutch and it shouldn't make any noise other than a firm click as it snaps on. However, they and their bearings do fail and can make metallic sounds.

[Nos4r2]

Originally Posted by jwalker

Except that manifold pipework after the turbo charger is pressurised by the turbo compressor so any leaks are outward.

Not when it's on intake stroke while idling.

[jwalker]

Originally Posted by Ian Brown

..my old one's made such a high screaming noise when they kick in at 2000rpm.

[doggypaddle]

Originally Posted by Nos4r2

Not when it's on intake stroke while idling.

JW may have a point though, the KAD 32 has a belt driven supercharger too in which case the pipework may be under pressure at tickover but only after the rootes blower.
i hadnt realised Volvo used compound charging until i looked at the KAD32 engine data.
Various different terminology used by different manufacturers dont help.
i generally call an exhaust gas driven centrifugal supercharger a turbo-charger, anything else mechanically driven i call a super-charger, whether its gee rotor, rootes blower, or a centrifugal blower, although a lot of manufactures call mechanically driven centrifugal compressors turbos too. confusing!

Well spotted JW.