good evening, i have a 98 quattro A4 2.8 with 105k..

lately there has been annoying hissing sound upon startup and sometimes frequent with the engine running for awhile.. just checking if this is a simple serpentine belt replacement needed or anything further(pump or compressor).
any help is greatly appreciated!!!!!!! thks -md

 

does it do it when you drive to, or has it at all?

if it is:



its the connection right above the red hose.

 

does it sound like air escaping or a super loud frog?

 

hi thanks for the response guys.

ok it is more like a loud hissing/whining noise but only lasts a minute or two.. im thinking its related to the a/c or thermostat ??

 

ok, so when you push the gas it has never hissed?

if not, then what i said is not the issue

 

also he has a 2.8, that pic is of a 1.8t motor

 

It only lasts a minute or two? Sounds like the Secondary Air Pump. Do the rpms drop by a few hundred when the noise stops (easier to notice while in park)? If that sounds right, scan for codes, you might find P0411. Hell, scan for codes anyway. Autozone and Advanced will do it for free.

 

yeah my car makes that noise aswell onlky when it first starts its really annoying lol i checked sounds like it might be comming from the belts not sure thow prob taking it to machanics soon

 

Air pump is more than likely your problem check the connections from the pump. You may get lucky but the pump does like to crack and break rivets

 

great thanks!! im gonna look it up in the repairmanual.. i just got a new serpentine belt todayand replacing it on friday.. i willpost a reply after installing and let you know if it has soved the noise...