Primary Turbo siren/whistle from 1500RPM

[woody919]

Hi Everyone,

I have a 2011 L320 TDV6 3.0. I know this is the Disco forum but I thought it get more support here as there is likely more D4 owners out there.

I got the RRS in 2017 with 90k on the clock. When driving it back from Sydney to Brisbane I got a siren like whistle from the primary turbo. The turbo was subsequently replaced and the noise gone. I kept the old turbo and it looks fine, no damage so I thought it may have been an exhaust gasket leaking. The body came off for this job.

6 years later at 170k the car has a cam shaft oil leak from the left side, dripping onto the turbo crossover pipe. So, I just had the body off again, this time to fix that oil leak. As I was driving out from the Indy (now in melb) I have a siren like whistle from the primary turbo again. I took the car back and got them to have a look, they are sure they haven’t touched the turbo when the body was coming off and on the car. They are very reputable and are very knowledgeable. The noise is there from 1500rpm and no difference in neutral or under load, same noise hot and cold.

so my question is, does anyone know if the turbo could have been disturbed whilst the body was coming off and on? I have no fault codes and no loss of power. Could it be the exhaust or crossover pipe gasket or a hole in the turbo outlet to the intercooler? This turbo is a genuine Garrett replaced only 5 years ago with 80k on it. I look after my car, always let it idle for a few minutes before shutdown etc so I am very surprised and annoyed to have this issue again.

thanks

[Eric SDV6SE]

Check that all intercooler hoses are tight and no clamps have come loose or off. There should be no reason to touch the turbo if the body cones off, the whine is always there, just usually very well insulated. Have they re installed all the heat shields etc? On my D4 I only really heard the whistle when I turned the snorkel intake 180 deg to face backwards during a windy beach drive, sounded quite cool actually (for a while), then too much like a GU Pootrol ....

[Graeme]

Are there any conditions when the engine is in that rev range when there is no whistle? Looking to establish whether the whistle is caused by pressure, boost or exhaust or simply revs.

[Eric SDV6SE]

Given that the turbo is driven by the exhaust gas flow velocity, it's always spinning when the engine is running, but not necessarily generating boost. So at idle and up to where it starts generating boost pressure it would not whistle, but as the speed ramps up, it will increase in noise, usually a whine until the boost release valve opens when the transmission changes gear, that's when you get a "whoosh" noise of boost pressure releasing.

Sounds to me you may have a leak in the air ducting, intercooler or air release valve. As you said you are not getting any boost pressure related error codes, it may be a small leak. Worst case is a failing turbo bearing, but they're a plain bearing, relying on oil feed to stay lubricated, so check that the oil lines to and from the turbo are not blocked. Turbo won't last long without oil.

[DiscoJeffster]

I’d put money on crossover pipe gasket leak.

[woody919]

Are there any conditions when the engine is in that rev range when there is no whistle? Looking to establish whether the whistle is caused by pressure, boost or exhaust or simply revs.

Hi Graeme, it seems to be there all the way from 1500 rpm. It’s still there over 3000rpm just other noises take over from it. It’s most noticeable with the windows up and seems the loudest around 40-60kph when you come off the pedal slightly. I’ve had a look around the turbo with no visible oil leaks and iv been driving it so I’m quite certain it’s getting the required oil.

[woody919]

Check that all intercooler hoses are tight and no clamps have come loose or off. There should be no reason to touch the turbo if the body cones off, the whine is always there, just usually very well insulated. Have they re installed all the heat shields etc? On my D4 I only really heard the whistle when I turned the snorkel intake 180 deg to face backwards during a windy beach drive, sounded quite cool actually (for a while), then too much like a GU Pootrol ....

Hi Eric,

I’ve always noticed a slight whistle but it’s now much more noticeable around the 1500 rpm mark. Everything appears to have been installed correctly. It’s got the same noise it had when I first got the car, and I’ve still got my old turbo (that made the same noise) and it’s got no damage so I doubt it would be the turbo, more likely a gasket or pipe leak. I’ve seen others on this forum with a similar issue and it turned out to be the crossover pipe gasket, I might see if I can get that looked at. Does anyone know how much work it is to get to that? It looks to me like it’s quite difficult to get to.