W210 300TD - Strange hiss on turbo

[Mikeyboy]

Hello, I seem to have developed a strange hiss when the turbo is working and gets a bit more pronounced when the throttle is at 100%.

So far I have checked:
Air filter - OK and seated correctly.
General look around the turbo - Looks fine, no obvious holes.


There is no lack in performance and there is no hiss when stationary and you rev the engine.

Any ideas??

 

[camerafodder]

I've never driven a turbocharged diesel that didn't have an audible hiss from the turbo when under load. There is no load when the vehicle is stationary so you're unlikely to get the same sound when you rev the engine. Is the sound new?

 

[Mikeyboy]

Yep, it's new...I know what you mean about turbo whine but this is more of a sound like a compressed air gun.

Not sure if it is related but the fuel filters are more than due for replacement but I doubt it could be that and there's no drop in power...

 

[Olivier]

I have a cone filter and defenitly you hear a wooshhh...
You might have a hole in the hoses that expand when under load?

 

[babz]

turbo spool??

 

[camerafodder]

Yep, it's new...I know what you mean about turbo whine but this is more of a sound like a compressed air gun.

Not sure if it is related but the fuel filters are more than due for replacement but I doubt it could be that and there's no drop in power...

Hi Mikey, I don't mean a whine I mean a hiss, like the sound of a compressed air gun. If the sound is new then my guess would be a leak on the compression side of the turbo.

Also, I know this may sound daft, but have you changed your driving habits recently, ie driving with the window down?

 

[Mikeyboy]

It is a new sound in the last week. I hardly ever have the windows down but I know what you mean.

I will try to drop the hose from the intake part of the turbo and to look at the vane...is that what Babz means by spool?

The only thing I haven't checked yet is the I/C pipes...How does the process work? I mean, is it air in to filter then through turbo, through I/C then in to plenum chamber??

Thanks for the help so far, it is appreciated.

 

[Dieselman]

Check the gaiter at the base of the steering column for splits.

 

[Mikeyboy]

As in it is letting noise in through the bulkhead?

I just bought a camera and was thinking of fastening it at the back of the headlight housing on the off side with a lamping light then taking her out for a spin then watching the video to see if anything obvious is is escaping.

When I revved the engine using the throttle send near the duovalve I couldn't see owt untoward but then it doesn't make the noise when staionary.

 

[Dieselman]

I doubt it's a boost leak as these cars only have short rubber pipes and they never go.
Hold your hand near the rubber pipe from the turbo and rev the engine hard, if it's leaking you will probably feel a blast of air.

Do check the gaiter though as when they split you can hear the exhaust pass through the cat ad the turbo noticeably more.

 

[Olivier]

Hi DM, I know one car that had the pipe bursted, it happen sometimes I guess..

 

[Dieselman]

Hi DM, I know one car that had the pipe bursted, it happen sometimes I guess..

A 300TD or a Cdi?
It does happen to Cdi, but virtually never to 300TD due to the long pipes being made from aluminium tube.

 

[Olivier]

it was a E300TD. Dunno where it was tho. I could ask

 

[Mikeyboy]

I'll nip out at luch time and check that gaitor.

I did look at that orange stubby pipe from the turbo and it looked fine but will put my hand near it on high revs like you suggest to see if I can feel owt.

I was going up a fairly long steep hill on me way home last night and I woulnd the window down, put it in 3rd so it was on boost then gently fed the trottle in and out and there was a noticeable lag in whoosh/his build up and fall off...exactly like comp. air so I reckon it is a turbo issue and not diff/trans.

Cheers.

 

[Mikeyboy]

OK, just been out and checked...


The gaitor on the steering column has split all the way round!

AND...

I then started to check the pipes...short stubby orange pipe on turbo seemed fine.

I then moved elsewhere and found the main air intake behind the grille had torn rubber that could be pulled in to the 'hole'.

I then put my hand in there and tried to partially obscure it, revved the engine and sure enough when the turbo kicked in it made a whooshing noise.

I had trouble with the headlights a couple of weeks ago and am now thinking that this rubber piece got partially ripped when messing about with the O/S headlight unit.

When the bonnet is open then the air flows freely through the intake and does not pull the rubber flap in but when the bonnet is closed then there is plastic from the grille in the way so I am thinking that the flap is being pulled in.

Was thinking of ripping it off to see if it cured the noise then poxy resining it back in place afterwards.

As regards the steering gaitor; Is it a case of not moving the wheel when the UJ is disconnected??

A really big thanks for all your help so far.

 

[camerafodder]

Thanks for letting us know Mikey. Looks like Dieselman was right about the steering column gaiter. I'm sure he'll be along soon to advise you on replacement.

 

[Olivier]

OK, just been out and checked...


The gaitor on the steering column has split all the way round!

AND...

I then started to check the pipes...short stubby orange pipe on turbo seemed fine.

I then moved elsewhere and found the main air intake behind the grille had torn rubber that could be pulled in to the 'hole'.

I then put my hand in there and tried to partially obscure it, revved the engine and sure enough when the turbo kicked in it made a whooshing noise.

I had trouble with the headlights a couple of weeks ago and am now thinking that this rubber piece got partially ripped when messing about with the O/S headlight unit.

When the bonnet is open then the air flows freely through the intake and does not pull the rubber flap in but when the bonnet is closed then there is plastic from the grille in the way so I am thinking that the flap is being pulled in.

Was thinking of ripping it off to see if it cured the noise then poxy resining it back in place afterwards.

As regards the steering gaitor; Is it a case of not moving the wheel when the UJ is disconnected??

A really big thanks for all your help so far.

Yes, make sure you get the key out the ignition before you remove the UJ to lock the steering wheel...

 

[Dieselman]

The column can only go one of two ways, so it would be either right or upside down...which I would like to think you would notice...

It's really easy to do, just unbolt the column and push it into the car, then pull the gaiter out.
Fit new gaiter and push into the car, then pull the column down and clamp back together, then from inside the car press the gaiter bead into place.

 

[Mikeyboy]

I have just been out and took pics...will try to upload.

While there I bent the rubber flap under the trim and we'll see if it makes any diff.

I'll get on to my bud to see if he can get me one (gaitor) from his MB dealership, thanks Dieselman.

 

[Mikeyboy]

Some pics...hope they upload ok...