Whistle

[Christophski]

Hey guys

Having recently just cured my boost leak a few weeks ago my car has this evening developed a very random high pitched whistle. Not a squeal but whistle. It only happens when I'm over 1 bar boost and isn't causing me to lose any pressure. Still hits 1.4 bar and holds it. Due to me being able to hear it clearly in the car is this a boost leak coming from the gauge or plumbing for it?

Thanks for any suggestions or advice in advance.

Chris

[sfrs4]

is it quite high pitched almost like a dentists drill type noise or just a whistle?

[Christophski]

I am not sure which I could compare it to. Why? Please don't say turbo.... There is no smoke and it sounds like it's in the car. I would be tempted to say the drill almost

[sfrs4]

with the rs4's the first sign of the turbos going is supposed to be a dentist drill type of whistle noise, luckly (touches the wooden window sill) i've never heard it personaly. hopefully it won't be and it's just a very small boost leak, can these be preasure tested like the rs4? worth doing if you can

[GavS2]

Interesting one there Chris, can't think of anything off the top of my head. If it was leaking boost it would show on the gauge, hope its not the turbo, if it gets louder or changes to a different tone i would be careful and maybe check the turbo dude.

[Tonks4x4]

Just check the metal flexible pipe from the wastegate to exhaust. There is a little arrow stamped on one end to show direction of the flow.

A forum member had a very similar problem and found this was the cause

[Christophski]

I did have to change the wastegate and flex pipe over. It can only go one way though cant it? Can it ruin the wastegate if it's the wrong way? Sounds like I better do some investigating tomorrow after work. I'm fairly sure running another leak test will test the plumbing to the gauge and show it if it's there. I hope it's an easy fix as it seems to bs one thing after the next recently. Last week the brakes went and I managed to fix them quite quickly and easily. Tomis where is the flow mark on the pipe work?

[Rusty]

I have a similar issue after changing turbos. There are a lot of things I need to check but one thing that I do know is that the pipe Tonks describes above has been altered on my car I have a proper one to fit and am hoping that it solves the issue but it's a very odd set of symptoms... as most S2 related issues are Anyway, worth taking it off and comparing to a picture or two, just ot make sure. In my case, a slightly different spec turbo could mean that there is a need for more WG air and thus the increased airflow has made the difference. Of course, it could be a leak

[Christophski]

Well just checked the flex pipe and found the arrow. It's pointing down as in towards the back of the car so is on the correct way for flow. Will make sure the blots are all nipped up tomo and will try run a leak test over the weekend if I can. Any other suggestions welcome. I just don't want it to be the turbo

[newsh]

If its a turbo whine it will go up and down in pitch as you modulate the throttle.

It could easily be the gauge plumbing or a vac line rubbed through on something sharp. A pressure test will find it if its a leak. I had a leak at the ECU on my coupe, the clip was done up tight but the tubing had squashed down and was no longer being clamped hard enough, cutting an inch off the end fixed the problem.

[Christophski]

Ok well the pitch remains the same and doesn't modulate. So I am guessing it's less likely to be the turbo. Back to testing for boost leaks. Oh what joy these cars are sometimes!!!!

[Christophski]

Well oddly enough on the way in to work this morning it made no whistle noise at all which is strange as I was playing with it a bit. Lsat night when I got home I did pop the guage out and have a fiddle but I didnt cut anything or do anything up tighter.... Very strange. Will keep using it until it does it again and then do some leak tests and have a listen. Personally I dont think its the turbo as there is no smoke from the car at all and last night the pitch didnt change with the throttle it was either making the whistle or it wasnt. (depending on if I was coming onto over 1 bar or letting off) so I dont think I have anything to worry about. The wastegate flexi pipe is on the correct way and is an original item. I just am getting frustrated at boost leaks etc as at the moment it seems to be one thing after another with the car and as my daily its getting annoying, expensive and getting me down as I like it to be a good decent car instead of covered with issues.

Will keep you posted as to if it comes back, gets worse or if I find a leak and manage to fix it.

Just out of interest when running a boost leak test, once I have put air into the system I am assuming even if there is no leak the air will escape some how? Where, how fast etc so I know what not to worry about....

Thanks guys

[newsh]

Injector O-rings can make a whistling noise.

Check the connection at the ECU, it took me ages to find as it seemed to come and go.

Have you renewed all the small bore vac pipes yet? If not it well worth doing as they will be old and decaying. You fix one leak and then the boost pressure finds another way out

If you boost test from the Maf hose to the metal boost pipe with the PCV system disconnected from the Maf hose and blocked off then the only way out is through the turbo seals, sometimes you hear a gurgling as air gets past them into the oil. If you pressure test from Maf hose with PCV disconnected but include the IM then you're testing the throttle body, all the small vac pipes and the injector seals too but you will get some leakage past the rings/valves etc. Worth testing the DV by sucking on the small pipe that actuates it, it should be sealed, if not the diaphragm has a hole.

[Christophski]

Cheers Bud. Will take a look later. I hope its not the DV as this was only fitted the other week!!!! It shouldnt be to be fair to the seller as is in good nick and is still boosting and holding pressure well. I hope its just a small leak somewhere and the tester kit will find it but will pull down the lining under the glovebox over next few days to check the ecu connection when I do the test.

[K Simmonds]

Just a thought, but might this noise just come from tired heater fan? Would explain the constant pitch regardless of engine speed.