hi all had my volvo xc90 around 5 month noticed a slight drop in power and oil drip from the metal skid plate under radiator so after searching the net I went for changing the intercooler which as it turned out was the problem it was bowed and leaking. so got it all back together today and went for a drive .
vehicle much improved more responsive but on pulling away once it gets to about 3000 rpm there is a very noticeable whistling/hissing noise a bit like a dump valve noise [none fitted] coming from the air filter housing / pipe that fits to the mass airflow meter I can get it to do it when stationary and revving the engine to about 3-4000 rpm but it dies off and is not constant.
is this normal boost noise now that the intercooler is new I have checked all pipes for tightness / holes or do I have more problems ?