Engine Hiss

[R34mac]

Hey guys,

I ran a few searches but couldn't find any topic that sounded like my problem. tonight I noticed a hissing noise coming from the rear of my engine (rb25det). haven't noticed it before so it must have started doing it in the last few days. can't really hear it when the bonnet is down but fairly loud when it's up.

it sounds like it's coming from the top of the engine right at the back. it doesn't seem to increase with revs and the car still runs fine at a solid 9psi of boost with no fluctuations. on shut down the sound continues for 2 seconds or so before you hear it reduce and then stop. i tried to pinpoint exactly where it's coming from and see if i could feel an air leakage but the engine fan pushes so much air past i couldn't really tell. can't see splits in any of the hoses..

any ideas chaps? thanks in advance..

Edited March 7, 2009 by R34mac

[and3_3]

Could be brake booster, could be aac valve

[R34mac]

thanks for the suggestions mate. in the light of day today i ended up finding out what it was - some kind of vacuum line which runs into the side of the plenum (right near the back) had a split along the bottom of it. no idea what it's for though, it didn't seem to really have much affect when it was leaking.

anyway i do like an easy fix so im happy

Edited March 8, 2009 by R34mac

[jeffworld2]

thats for the boost gauge on the dash. They crack a lot actually, just too thin

[and3_3]

Standard boost gauges are gheyyy