Secondary Air Pump

[NZ BMW 368]

Hi Team,

I think I've got a dying secondary air pump on my E39. I've got a famous jet engine noise on cold start which is very loud. It is not constant sort of goes wrrrrrrrrr then quiet then a couple of other big wrrrrrrr's and then is silent.

Has anyone got any photos or diagrams of exactly where it is so I can check the hoses? Whilst having a jet plane is all very exciting I would like to get rid of this noise, but I always struggle to find where stuff is in the engine bay based on the closeup pictures which are usually posted on the internet.

Thanks.

[*Glenn* 854]

Give me a call Nathan... I'd need more info from you. Phone is quicker (09) 2722546

[mossline 15]

Keep us posted on what this is. Sounds like it could be interesting! Best of luck and hope it isnt too expensive

[NZ BMW 368]

Sorry Glenn, I would have missed you being in at the office - I took a video this morning with the bonnet up. I'm starting to wonder if it's not the pump but a belt or pulley - the alternator belt was replaced by the dealer during the week, so hopefully it's not that.

Here's the video:

http://youtu.be/Jsr7YwduldU

[Greg111 13]

That's a terrible noise, trying to think where the air pumps are on those, E46 ones are on the left hand side when looking into the engine bay, big drum looking thing, have heard them let go and does sound similar to yours....although it does sound like a pully bearing letting go, how long does this noise last for, if only a few minutes my guess would be the pump.

My E36 has just started doing the same thing, it's the pump on mine, sounds like a huge air leak (which i'm guessing is exactly that), stops after a minute or so once the engine has some heat in it.

[NZ BMW 368]

Mine stops by the end of the video - the louder noise is the unusual one, the camera is just amplifying all the other noises which is what you always get with cameras. So it does not last very long at all. Which could suggest a pulley... Would the power steering pump or anything like that make a noise at start up? Is there any way this could be related to my recently changed belt? Perhaps the tensioner not being adjusted correctly or something?

[Greg111 13]

Mine stops by the end of the video - the louder noise is the unusual one, the camera is just amplifying all the other noises which is what you always get with cameras. So it does not last very long at all. Which could suggest a pulley... Would the power steering pump or anything like that make a noise at start up? Is there any way this could be related to my recently changed belt? Perhaps the tensioner not being adjusted correctly or something?

I would assume if it was one of the pullies the noise would be there the whole time not just on start up, if the car is hot and you start it does the noise come back?

[Docile 64]

the main belt pulley on my m50 screeched like that when it was buggered it would not spin at all. but it was continuous.

try and use a long ratchet extension and place it on the top main belt pulley and put your ear on the extension. you should be able to hear it from the extension if its vibrating abnormally or making a noise from the pulley. be careful not to hit any moving parts and not wear loose clothing.

Edited February 3, 2012 by Docile

[NZ BMW 368]

I would assume if it was one of the pullies the noise would be there the whole time not just on start up, if the car is hot and you start it does the noise come back?

I'm going out to the airport this afternoon so I'll let you know when I get back. It does not happen when I'm driving I've even tried manual shifting to keep the revs up and I don't hear any difference even with my windows down, AC on or off etc.

I'm kinda hoping it is a pulley as those pumps are kinda pricey and to be honest a bit pointless to the functioning of the car (with the exception of emissions controls).

Is there a rebuild kit for the pump bearings?

[NZ BMW 368]

I would assume if it was one of the pullies the noise would be there the whole time not just on start up, if the car is hot and you start it does the noise come back?

My tools are very limited to be honest - What I might try is just reaching in there with the engine off and giving each pulley a wiggle, my understanding is that there should be minimal play in them at all - if one is significantly more than the others, then that might be the defective one. The space with this engine is so tight I don't think I would even be able to get any tools in there safely whilst it was running anyway.

[Greg111 13]

I'd say it will be that pump, disconnect and remove it, soley for emissions. Not needed, plenty of cars come into work with the pump not there or just unplugged, have replaced a few and yes they are expensive.

[NZ BMW 368]

I'd say it will be that pump, disconnect and remove it, soley for emissions. Not needed, plenty of cars come into work with the pump not there or just unplugged, have replaced a few and yes they are expensive.

Just tried a hot start and there was no abnormal noise - guess it must be the pump.

I'm happy to pull the cord on the pump - but will this trigger a check engine light? I would imagine the the O2 sensors will not be getting the correct signals if the pump is disabled.

Does anyone have an exploded view of the pump on an e39? I'm keen to pull the plug and try a cold start to see if there is any noise.

Also look online at some of the US based forums there is also a concern that NOT having the pump can cause excessive carbon buildup. Any ideas on this?

Thanks for all the input so far guys!

Edited February 4, 2012 by NZ BMW

[*Glenn* 854]

Where are you situated Nathan ?? It's easy to check the pump, it can be activated with the right scanner and checked either hot or cold. The youtube clip sounded like an idler or tensioner bearing. We had a e46 in last week with a similar noise. The idler bearing was seized and would'nt spin properly cold. Is there any belt rubber transferr onto the idler or tensioner bearings ??

[NZ BMW 368]

Where are you situated Nathan ?? It's easy to check the pump, it can be activated with the right scanner and checked either hot or cold. The youtube clip sounded like an idler or tensioner bearing. We had a e46 in last week with a similar noise. The idler bearing was seized and would'nt spin properly cold. Is there any belt rubber transferr onto the idler or tensioner bearings ??

I'm located in Newmarket - that did come to mind as I had a previous car where the pulley was noisy when cold but was fine when hot. I didn't see any belt transfer, but like I said before I can't really see a lot of of the pulleys clearly in the engine bay.

Would you be willing to come and have a look at it? How much do you charge for a call-out? It would be nice to have an indication as to what is going on for when I get it fixed.

[*Glenn* 854]

Sorry.. I don't work on cars off the premises. I need to access tools and diagnostic equipment when diagnosing faults and it's a bit hard to put a hoist and the rest of the gear into the back of an Xtrail

[NZ BMW 368]

Sorry.. I don't work on cars off the premises. I need to access tools and diagnostic equipment when diagnosing faults and it's a bit hard to put a hoist and the rest of the gear into the back of an Xtrail

Haha, no worries - I will send it somewhere on Tues/Weds when everyone is back at work. It's always a bugger that these things happen on a long weekend!

[*Glenn* 854]

Haha, no worries - I will send it somewhere on Tues/Weds when everyone is back at work. It's always a bugger that these things happen on a long weekend!

You won't be able to buy new parts either over the WE. We can look at it for you next week... just give me a call (09) 2722546

[NZ BMW 368]

You won't be able to buy new parts either over the WE. We can look at it for you next week... just give me a call (09) 2722546

Thanks for the offer, but it's just not practical for me to try and get all the way out to Botany and then backto the office on a weekday during rush hour.

I'll have my local mechanic look at it.

[NZ BMW 368]

For what it's worth and for anyone who wants to know if appears that it may have been the alternator pulley. According to my mechanic it was fairly well buggered and since replacing it the sound has not come back. According to them the alternator runs a bit harder at the initial start-up and this is why the sound may have been so pronounced.

Kinda annoyed that this did not get picked up when it was in for work the other week given that the alternator belt was replaced. One would think that would be the opportune time to check the pulleys and possibly drum up some more business...

[RustyItalian 11]

Just caught this topic and the pump on my car screams exactly like a gas turbine (which are my expertise) on cold starts. However as the pump shuts off after about 30 secs and the noise does not concern me I happily ignore it. The wicked burble that the exhaust makes when the pump is running is also appreciated, pity is isn't permanent.