Hi! I hope someone can help me with this issue.
Yesterday, out of the sudden my 115HP S40 1.9D began to produce a very loud hissing noise when accelerating hard. If you accelerate gently, no noise. However, no smoke, no power loss, just this scaring sound (like a jet taking off...) when the turbo (Garrett) kicks in.
I went to my mecanic (no Volvo service in my district) who could not find the cause (he said he needed half a day at least to take the engine off, to look for the defection...)
Any ideas, please ?!
Thanx in advance!

hi.
if it sounds like compressed air escaping, try tracing the turbo pipe back from the turbo to the intercooler and to the fuel injection. this has happened on a few of my vans, (mercedes sprinter) the boost from the turbo was being lost from a split in the pipe leading to the intercooler, at first no effect to performance but slowly as the split got worse it started to effect the performance. inspect the intercooler if possible. i have the same car and havnt had time to get under the bonnet properly but i do know there isnt much space at the front of the engine.