Hi all!
I have a 1999 Chrysler Voyager 2.5TDi, which i have owned for about 3 weeks (and loved every minute of it!)
Now it's got warmer here I've been driving around with the window down and noticed that when the turbo is boosting I can hear what appears to be pressurised air escaping. It's quite loud, but only happens when traveling along. I got my kid to rev the engine while i checked under the hood and all seemed ok - the inlet pipes all pressurised as they should and i couldn't hear the noise, yet when i drive it along the road the noise is quite loud.
Is this normal? I'm not sure how long it's been doing it or if the performance has been affected as I've not been driving it long.

In my past experience with petrol turbo engines i would have put it down to a fault on the wastegate, releasing pressure too early. Does this sound right to anyone? I've never had a TDi before so don't know if a leaky wastegate on one of these would make this noise (is the air released back into the system or atmosphere on this car?), plus it's really awkward to investigate as it only does it when the car's moving.

Has anyone else come across this, or is it normal?

 

Possibly sounds like a rubber turbo intercooler pipe split. I had the same on a Shogun TD. It was hard to find as the split could not be seen when the car was stood still. When the engine moved whilst driving it opened up the split allowing air/vacuum to escape.
A blocked air filter can give a similar symptom so check this first.

Cheers Mark

 

I changed the filter already but it made no difference, although the one that came out was almost solid with dust.
I'll check out the hoses in the morning, thanks for the suggestion matey [sm=smiley20.gif]
I'll let you know how i get on.............

 

I assume you know the difference between whistle (bad turbo) and escaping air (what's the mileage on that car?).
once you determin the sound, it will be a lot easier.
the way you described it, you have an air leak, just like bentleyblok said. leak can be anywhere from engine head and rear muffler.

also, I think you are mixing two things.
every turbo engine has wastegate valve, and that one bypasses turbo back to exhaust pipe.
only petrol turbo engines have Blow Off Valve (BOV) which releases pressure into the atmosfere or back to exhaust (depending of the type), and that's that psssshh sound you can here every time a turbo race car changes gear.

 

It's definately an air leak, the turbo sounds normal. I've more or less had the whole intake system off and inspected all the hoses & replaced the jubilee clips, and found nothing wrong there. I've also inspected the exhaust system and there's no sign of a leak there either. I've driven it with the sliding door open and a mate hanging his head out (on a quiet dirt road!), and the sound's coming from the engine bay. This is sooooo frustrating!
The only places I couldn't look at were the actual turbo, because it's so hard to get to without removing too much, and the area behind the front bumper where the large air hoses run to and from. Is this the intercooler? (looks like a radiator). I'm thinking this might be worth investigating when i get more time off work.
Thanks for your help so far, it's very much appreciated!

 

part looking like the radiator is intercooler, but you definetly don't lose intake air on that place.
maybe on the surrounding hoses and clamps, but not on the intercooler.

since you are unable to determine where is it coming from, make sure that sound changes according to engine revs. that would indicate problem with engine, or air (but you couldn't hear anything while your son was reving the engine!!!!!).
if the sound changes depending on car movement, it's something else.
exhaust can be checked: while engine running, put your foot on the exhaust pipe, blocking the exit of gases. if you have a leak in exhaust, the sound shoud increase.

I'm telling you this becouse air leaks are usually easy to find, becouse of that whistling sound they produce.

if nothing else works, try recording the sound together with picture of speedometer and engine revs.

 

I'll try the exhaust-plug method after work tonight. The noise comes when the turbo boosts, at around 1800 - 1900 RPM, and gets slightly more intense as it revs up to 2000 - 2100, and then stays the same as the revs get higher (but still only does it while traveling).

 

Did you check the turbo bolts were tight? You could have air leaking from the gasket... or the hot air might have burnt the gasket away. Also, the noise will only be heard when driving as the engine is under load then, this effects manifold pressure which is why you cant hear it when the car is stationary.
Cheers Mark

 

I've got a couple of days off coming up soon, so I'm going to try and get to the bottom of this.
The turbo is just about the only place left that i haven't looked, so it must be from there, plus, from inside the car the noise seems to be coming from just the other side of the bulkhead - where the turbo sits. I tried the suggested exhaust plugging method, but that didn't turn up anything (exhaust has no leaks).

I'm going off to get a set of ramps so i can get right under it and have a good look around. If it is the turbo gasket, do i need an OEM replacement, or can i buy a universal 'cut to size' kit?

Thanks everyone!
Austin

 

After several hours of head scratching and hose-clip tightening i've found the problem!
It started to make a noise like a trumpet when under boost, even when the car was ststionary, so i got her up on ramps and traced the sound to the only place i haven't looked.......... you guessed it...........the INTERCOOLER!
There was a lot of corrosion to the fins and the air was escaping through it.......
Just needs a new one now and i'm sorted!
Thanks to everyone that helped!