air/hissing noise under acceleration

Simonish

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Nov 5, 2005
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Leigh, Lancashire
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C Class Coupe
Hmm

Hope this doesn't sound too expensive - had diesel injector seals replaced in February and jsut a while back had some intermittent power issues which seemed to point to MAS sensor, car went to low revs only mode after about 20 mins, then problem went away, replaced MAS anyway (£45) but now the low rev mode is back together with a hissing noise when you try to accelerate, I removed the top cover and the injector nearest the screen/bulkhead is filthy whereas the others are clean, it also seems to be making a noise (the hissing sounds like the wastgate on a rally car but all the time).

Do I suspect a turbo leak or would an injector seal cause a) the car to run in low rev mode and b) cause the hissing noise

I may be back to the stealer who charged me an arm and leg in February but only replaced 3 seals

Car is a W203 Coupe C220 CDI Auto

Simon
:confused:
 

GazCaff

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Check the jubilee clips on your intake ducting. A leak from it would cause the mess and would cause your car to go into limp mode due to the boost discrepancy to the ECU.
 
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Simonish

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Will do though I tightened those up yesterday, I got a bad feeling it is coming from the rear most injector so today I will speak to MB Bolton to understand why when they replaced 3 seals they didn't do the 4th! - from a fellow Leyther thank you :)
 
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Simonish

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Problem is the rear catalytic converter is blocked £ouch, methinks tis time to look at alternative workarounds to the Cat which is apparently blocked - current thinking is drill/punch through (I know this is bad but gets the car working until I can afford a cat) or just replacing cat with a length of exhaust pipe bracketed in place

Any other suggestions which avoid around a £650 bill feel free
 

KLP 92

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Simonish said:
Problem is the rear catalytic converter is blocked £ouch, methinks tis time to look at alternative workarounds to the Cat which is apparently blocked - current thinking is drill/punch through (I know this is bad but gets the car working until I can afford a cat) or just replacing cat with a length of exhaust pipe bracketed in place

Any other suggestions which avoid around a £650 bill feel free

Remove the cat and replace with a through pipe. Should cost around £100 or less. Cats are not required for MOT on a diesel, so no disadvantage with removing it apart from the car may be slightly more throatier in the sound department, but you do get a bit more BHP.
 

GazCaff

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Simonish said:
Will do though I tightened those up yesterday, I got a bad feeling it is coming from the rear most injector so today I will speak to MB Bolton to understand why when they replaced 3 seals they didn't do the 4th! - from a fellow Leyther thank you :)

Hopefully I'll see you at the next GTG then! Although I now live in Leigh, I have to confess to being a Woolyback from Sint'elens originally.
 
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Simonish

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Leigh, Lancashire
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All sorted now, the car is kind of de-catted. Removed back box, insert steel tube into exhaust pipe, hit with hammer, wiggled about a bit and empted honeycomb material out, started car, blew rest of loose material out, put back box back on and the car runs sweet and with a few extra ponies :)

Thanks to all
 

Dav

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Have just been reading about the hissing noise - I have a 220CDI and am getting a whistling noise from about 45/50mph. I was wondering if it could be a vacuum leak, but maybe its the cat. I live in Bolton, but don't fancy paying big bucks to MB Bolton
 
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Simonish

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Nov 5, 2005
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Leigh, Lancashire
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C Class Coupe
Well if the car is running in limp mode, it could be a blocked cat or the beginnings of one, it would be worth getting the car on the diagnostic (STAR) and seeing what the result is, MB Bolton didnt charge me for that this time around but they normally would do, I would suggest trying the MB independant in Winwick - Mercedestech I think they are called (behind B&Q warehouse at Winwick) I will try and get the number tomorrow and post it here - they are cheaper for a diagnostic
 

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