Car sounds like vacuum cleaner on start

[philthy]

Hi folks.

My car has taken to sounding like a vacuum cleaner for about a minute when I start it from cold. Any idea what this might be? I popped the bonnet this morning to try and listen to where it was from but couldn't really pinpoint it. It sounds like a motor/ fan spinning at high RPM which winds down after about a minute. Also, the idle appeared to drop (to normal speed from slightly high) when it stopped.

Cheers,

-Phil,

[noone]

Its not just the choke? My car sounds rough, idles around 1000 rpm for 30 sec - 1min before settling down.

The combustion is much richer, which helps protect the engine from damage when cold.

[philthy]

hmm, not sure. It's a distinct fan/ motor kind of sound, and fairly loud. High pitched though, not like the cooling fan.

[mattyf]

hmm, not sure. It's a distinct fan/ motor kind of sound, and fairly loud. High pitched though, not like the cooling fan.

sounds like an auxiliary air pump problem.

[philthy]

sounds like an auxiliary air pump problem.

Hmmm. What does that do?

Maybe I have a split pipe or something.

[mattyf]

Hmmm. What does that do?

Maybe I have a split pipe or something.

something to do with making cleaner exhaust emissions on startup.
the bearings in the electric motor could be u/s.
you could check for leaks by feeling the small hose that runs from the airbox to the auxiliary air pump when its running

[philthy]

something to do with making cleaner exhaust emissions on startup.
the bearings in the electric motor could be u/s.
you could check for leaks by feeling the small hose that runs from the airbox to the auxiliary air pump when its running

Will have a look at the hose. I googled auxilliary air pump and what came up did look familiar. I think it hangs off a bracket on the front of the motor and that was where the noise was coming from.


Thanks mate.

[Joe Chu]

Will have a look at the hose. I googled auxilliary air pump and what came up did look familiar. I think it hangs off a bracket on the front of the motor and that was where the noise was coming from.


Thanks mate.

Air pump pumps air into exhaust on cold start up to heat the catylyst up for cleaner emissions and get the cat up to temp quicker. The pump filter might be dislodge causing the noise?

[philthy]

Air pump pumps air into exhaust on cold start up to heat the catylyst up for cleaner emissions and get the cat up to temp quicker. The pump filter might be dislodge causing the noise?

Hi Joe. Where is the pump filter located? I felt the pipes coming from the pump yesterday and had another listen. Couldn't feel any leaks and the noise definately seems to be coming from the pump.

Will take it to the mechanic when I get a chance.

[Petrina Polo]

Does the noice stop after 30 seconds or so... if so its normal. forget about it..

Pull the hose off the airbox, start the car cold and you will feel the vaccumm, after 30 seconds stops.

Maybe you hose has come lose somewhere for the additional noise..

I thought the same thing, went to VW about it and they said forget about it, normal

[philthy]

Does the noice stop after 30 seconds or so... if so its normal. forget about it..

Pull the hose off the airbox, start the car cold and you will feel the vaccumm, after 30 seconds stops.

Maybe you hose has come lose somewhere for the additional noise..

I thought the same thing, went to VW about it and they said forget about it, normal

Yep it does stop. It's just a whole lot louder than it's ever been (never noticed it in the 3 yrs I've had the car).

[marco polo]

My car had a very loud noise only on cold start it was the Aux air pump take it back to VW mine has been changed twice now under warranty.

[philthy]

My car had a very loud noise only on cold start it was the Aux air pump take it back to VW mine has been changed twice now under warranty.

Yep, I'm pretty sure thats what it is. Car is out of warranty now though. Did they give you any indication of what they were worth? My googling would seem to indicate that they are expensive little f***ers... for something that really doesn't do much (helps the cat heat up on cold start).

The fact that yours was changed twice doesn't say much for their reliability. Did they change the valve on the line as well? Apparently if you don't do that condensation will keep getting into the pump and causing it to shag itself.

[RhysQ]

sounds like an auxiliary air pump problem.

this is what I was told it was.... probably just the hose has come away.

[ml16]

Yep, I'm pretty sure thats what it is. Car is out of warranty now though. Did they give you any indication of what they were worth? My googling would seem to indicate that they are expensive little f***ers... for something that really doesn't do much (helps the cat heat up on cold start).

The fact that yours was changed twice doesn't say much for their reliability. Did they change the valve on the line as well? Apparently if you don't do that condensation will keep getting into the pump and causing it to shag itself.

Sorry for the grave-dig, but which valve do you refer to and on which line? I've got a new air pump but there is still water/condensation getting in. I had an engine light come on and it was diagnosed as either the silver valve near the air-box, or the solenoid on the LH side of the engine. Any ideas which is more likely and what is the common fault here? I thought a 6 year old car would be a bit more reliable, maybe not?