307 2.0 HDi 2007 boost control hissing

Hugh Venables

Hugh Venables

Member
Fellow Frogger
Joined
Mar 7, 2012
Messages
125
Location
Ferntree Gully Vic
Our 2007 307 2.0HDi has started making a hissing sound when the boost is being controlled. The car's performance is not affected at all. When accelerating hard there is very little noise but as I ease off the hissing sound becomes louder. It is loudest on light to moderate engine load. If you use engine braking to slow down there is some hissing too. I assume there is a duct/pipe/hose from the boost control valve to the turbo inlet that is leaking. It is extremely difficult to see any of that behind the engine. Is anyone familiar with the back of the engine to make any suggestions? How difficult is this going to be to fix? I worked it pretty hard last weekend with the caravan and it doesn't seem to be getting any worse or causing any other problem.
Thanks,
Hugh.
 
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No expert here but....
Check the vac unit off the LHS of the head, (looking into the engine bay...) and then trace the hoses down to the two vac solenoids....they might need changing or there is a tear in a line????

Or the EGR...but a serious leak around there will limit the get up and go.....
 
Im presuming he saying its the vac that boost the brakes ,could be interesting towing a caravan, pugs
 
The brakes are not affected either. I don't think it is any sort of vacuum leak or a control problem. When the turbo boost is being controlled, the excessive air being dumped from between the turbo and the inlet manifold is leaking to atmosphere where it can be heard instead of being ducted back to the ducting on the inlet side of the turbo. There's a guy at Alpine Affair in Ringwood who seems to know these very well. It's booked in for him to have a look/listen on Tuesday.
Hugh.
 
WE HAVE TWO 307 HDIs IN THE FAMILY ATM AND A CITROEN PICCASO WITH THE SAME ENGINE, SO AM INTERESTED TO HEAR ABOUT ANY IDIOSYNCRASIES AND THINGS TO WATCH OUT FOR, KEEP US POSTED,, PUGS
 
pugwash said:
WE HAVE TWO 307 HDIs IN THE FAMILY ATM AND A CITROEN PICCASO WITH THE SAME ENGINE, SO AM INTERESTED TO HEAR ABOUT ANY IDIOSYNCRASIES AND THINGS TO WATCH OUT FOR, KEEP US POSTED,, PUGS
Click to expand...

No need to shout. FWIW uppercase is more difficult to read.
 
Di took the car to Alpine Affaire and they spent some time driving and put it on a hoist but were unable to diagnose without dismantling. They didn't think it was doing any harm or losing any power and didn't charge. If I could find an engine out of the car I might be able to see what it might be and where to start. The back of the engine is extremely inaccessible. Strangely the sound seems to come from the extreme left side of the engine bay when the turbo plumbing is mostly behind the engine. Maybe I might see something if I pull out the battery box.
Hugh.
 
It's still the same. I reckon it was quiet one day and noisy the next and the noise level has not changed since it started. The performance is still not affected at all. Had to replace the battery the other day and had a look down the back with a mirror and had a feel but no inspiration, it's too tightly packed in there. I suppose we either pull a lot of stuff out, maybe the engine or put up with a bit of noise. Actually, I think I might be getting used to it!
 
Does anyone out there know if the boost is controlled on the exhaust side or the fresh air side? Could I be wrong in deducing that it is boost control that is leaking?
Thanks,
Hugh.
 
Still no resolution to this. The turbo is controlled by varying the vane angles, not by any sort of waste gate or other gas pressure relief. It has been on a dyno with the windscreen wiper panel and engine cover removed. They could hear the hiss clearly but couldn't find it without further dismantling. I don't think it is much louder if at all than when it started. It doesn't seem to cause any other problem. A smoke test might be worthwhile but it is so tightly packaged that the smoke leak source would probably be difficult to find. Any suggestions welcome.
Hugh.
 
Hugh Venables said:
Still no resolution to this. The turbo is controlled by varying the vane angles, not by any sort of waste gate or other gas pressure relief. It has been on a dyno with the windscreen wiper panel and engine cover removed. They could hear the hiss clearly but couldn't find it without further dismantling. I don't think it is much louder if at all than when it started. It doesn't seem to cause any other problem. A smoke test might be worthwhile but it is so tightly packaged that the smoke leak source would probably be difficult to find. Any suggestions welcome.
Hugh.
Click to expand...
Well it is still the same. As well as the hissing there is, and I think it started at the same time, a mild soft clattering noise that varies with different throttle positions and engine load and speed. About 12 months ago there was a brief but very loud single cylinder knock for only a few seconds and hasn’t repeated. I can only imagine something got into a combustion chamber and shortly after went out the exhaust. Could there be something loose or unwanted in the intake tract? Could a small piece have broken off and got sucked in? It has now done 270,000 km doesn’t burn any oil and runs a well as ever with still good fuel consumption. Any ideas?
 
Sounds to me a slight boost leak. Turbo will spool harder to keep the pressure it’s meant toeven though has a SLIGHT leak. Common on hdi 407s the intercooler hoses perish from oil in the intake system and over time the turbo boost pressure make a hole.

Also there’s a few boost solenoids that can leak.

Can’t be too big as will throw a code or go into limp mode. Only way is to put the hoses off and look .

If your happy too keep driving until either happens but I’d get on top of it.

Hope this helps

Ben
 
BP505v6Turbo said:
Sounds to me a slight boost leak. Turbo will spool harder to keep the pressure it’s meant toeven though has a SLIGHT leak. Common on hdi 407s the intercooler hoses perish from oil in the intake system and over time the turbo boost pressure make a hole.

Also there’s a few boost solenoids that can leak.

Can’t be too big as will throw a code or go into limp mode. Only way is to put the hoses off and look .

If your happy too keep driving until either happens but I’d get on top of it.

Hope this helps

Ben
Click to expand...
Thanks Ben. This problem began very suddenly about 5 years and about 100,000 km ago. One minute it was normal, the next we had these noises and it has stayed the same since then, apart from the short lived but very savage engine knock. Could one of those solenoids leak and rattle and eventually shed something into the inlet tract? Where are they located? Thanks, Hugh
 
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