What is this noise - Turbo Issues ??

[minsky66]

Hi All,

Hoping someone on this site might be able to lend some advise.

I have a MK V Golf Comfortline TDi purchased last July as new, when I took it in for it's 30,000 km service the dealer gave me a call and advised they had noticed oil on the side of the engine, they were unsure what it was.

Investigations revealed a leak from the seals around the turbo where it mounts to the motor.

The turbo was replaced under warrenty. Since doing so the car now has a whine noise at low rev's and & low speed ( 1000 -1500 revs). It sounds a bit like a siren or radio interferance.

Anyway the car has been back a few times and adjustments have been made but the noise persists.

The dealer arranged for someone from VWA to take a look and have advised it is within Spec ?? VWA have offered to replace the turbo again, however have made a stipulation that if replaced and is no better that no further work will take place on this issue. The car has just had it's 45,000 kms service.

My concerns are :

1. What is causing the noise?

2. when I bought the car it did not make this noise, why is it doing so know ?

I have driven some of the other TDI's (loaner cars from the dealer) and none bar one make this sound, The one that did was a MK 6 2.0 Tdi.

Any advise you can lend would be greatly appreciated.

Thanks

Michael

[vmq6695]

0. Manual transmission or DSG?

1. Park the car (in neutral if a manual, in P if DSG) with a warm engine (ie around 10 minutes with the engine at driving speed to warm up both oil and coolant). Open the bonnet. With someone at the wheel and you listening to the engine, do you hear the whine at:

a. idle speed;
b. 1,000 rpm;
c. 1,500 rpm;
d. 2,500 rpm;
e. 3,000 rpm.

2. Drive the car with a warm engine (as above) to a location where you can accelerate hard (eg a hill slope, a highway on-ramp). Windows down. Accelerate aiming to bring the engine to not less than 2,500 rpm before changing up a gear (if DSG, manually shift; you can select gears to keep your roadspeed legal as appropriate and necessary). Do you hear the whine:

a. at all;
b. only at engine speeds below turbo boost;
c. at all engine speeds, regardless of turbo boost;
d. only at engine speeds above turbo boost.

Cheers

V

[minsky66]

Thanks for the info vmq6695. The car is a DSG (I knew i missed something )

The dealers are telling me that the noise is definatly coming form the turbo and that it is normal or at least withing spec???

So far as I can hear up until now. I get no noise at all other than between the 1000 -1500 rev mark and at low seed like when you are crawling in traffic between 1st and 2nd gear.

I will be trying out what you suggest once I get a chance.

[HiTorque]

Thanks for the info vmq6695. The car is a DSG (I knew i missed something )

The dealers are telling me that the noise is definatly coming form the turbo and that it is normal or at least withing spec???

So far as I can hear up until now. I get no noise at all other than between the 1000 -1500 rev mark and at low seed like when you are crawling in traffic between 1st and 2nd gear.

I will be trying out what you suggest once I get a chance.

Turbo kicks in at 1750rpm so it could be from it as it's new, and I have read somewhere about this noise, but could be from GTI owners...I have 4y.o. 75K km, no noise at all, touching wood...

[Transporter]

It could be gasket between flange and pipe that connects to the EGR valve. If they didn't replace it, there could be a small leak that could make the whistle sound.

[minsky66]

Turbo kicks in at 1750rpm so it could be from it as it's new,

I thought this at the start as well, but it has now been in the car for 15,000 km's and it is still whining..

What I don't get is why they have offered to replace it again if it is ok and within spec as they say , yet stipulate that if it is still noisy they won't touch it. I also don't know how they can put this condition on an issue if it did not do it when the car was purchased ???.

Thanks for the input.

[minsky66]

It could be gasket between flange and pipe that connects to the EGR valve. If they didn't replace it, there could be a small leak that could make the whistle sound.

I did think it was something like this and asked them to check for leaks on all the connections, which they stated they did and there were none

They seem to think that it could be the turbo itself, perhaps teh way it was caste or put together or whatever .. and hence saying they can replace it.. only problem is if it is worse than now I get stuck with it that way..

Just wanted to add that the dealer/service department have been very patient and helpful and am happy with thier service , I just want a car that doesn't whistle

[gldgti]

They seem to think that it could be the turbo itself, perhaps teh way it was caste or put together or whatever .. and hence saying they can replace it.. only problem is if it is worse than now I get stuck with it that way..

nope, it doesnt really work that way.

they are offering to replace it agian because they want to keep you happy - they dont want to do it again after that because there is no other problem apart from the noise, and they certainly can't go replacing good turbo's because its making a whining noise but not causing any specific mechanical issue.

its very difficult to diagnose noise sources via the internet ( ) however, i have heard turbo diesel cars make many different noises for all kinds of reasons. as transporter stated, it could be a small leak somewhere... or any number of other things.

small turbo's make plenty of noise at low gas pressure's since they are always doing high rpm, so its no surprise to hear turbo noise at idle with a setup of this kind, providing there is some kind of leak somewhere to let hte noise out.

some of you are noting that "the turbo comes on at 1750rpm" but this is merely when the engine management closes the vanes and get it really spooling - infact, even with vanes fully open, the turbo is spooling fast enough to make plenty of noise from idle up to that rpm. there is no reason to rule out the turbo as the sourse of the noise, but it is not necessarily the problem itself. a leaky gasket somewhere in the system may well be leaking and producing no visible signs - i've had this myself - you can hear a leak, but yet there is no real mechanical issue or problem, apart form a small gas leak somewhere. small exhaust leaks upstream of mufflers but behind the turbo will also be very noisy (turbo downpipe connection, flexible joints can develop cracks).

i hope this helps in some way. i would rule out replacing the turbo until (if ever) something serious happens. i dont see any reason to connect the oil deposit issue to the problem either, and i would further offer that there is no place for oil to leak out between the turbo and the engine - only exhaust. oil could possibly leak from the turbo oil return line, or the supply line, however this problem should have been picked up by the service mechanic, if it was the cause.

HTH

[minsky66]

thanks gldgti for the great info.

I seem to recall that they said something about a small leak from the oil return as well, however they stated another larger oil leak from somewhere else as well and then replaced the turbo. thats when the whine started.

I guess I will try hunt around to see if I can locate any leaks, cracks in hoses etc. The noise has diminished somewhat over time , however is still quite noticable.

Thank all for the info. This site is great

[gregozedobe]

I have read of small exhaust leaks making sounds that some diagnosed as a turbo on the way out, I have also read of turbos disintegrating soon after they started making a "siren" noise (believed to be the impeller lightly touching the housing), but I have also read of TDIs that make these sorts of noises and keep on going almost forever, functioning perfectly normally.

As GLDGTI syas, there are no hard and fast answers, particularly when diagnosing noises via text on an internet forum.