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-   -   Sounds like a jet plane (http://forum.e46fanatics.com/showthread.php?t=906858)

M4RKY N 03-02-2012 01:26 AM

Sounds like a jet plane
 
When I first start my car it sounds like a jet plane! Then after say 2 minutes the noise goes. I have been told its my vacuum or something like that. Is there a way of sorting this noise out? Or is it a normal noise for these cars? It's done it since day one of be buying it but I have noticed lately it's staying on doing that noise that bit longer

deadpass 03-02-2012 01:30 AM

That would be the secondary air pump, it's normal.

Solidjake 03-02-2012 03:37 AM

Yup, the sap. It heats up the o2 sensors

dmax 03-02-2012 04:09 AM

It might be normal, might be a sign that your hose is corroding internally and clogging the valve. Squeeze the hose and if it feels soft and squishy, replace hose...and check inlet to the valve (if you have one) and see if it's clogged. If so, remove gunk...with dental pick, vacuum, whatever.

Also, just read that someone here rebuilt his pump...I assume that means replacing bearings on it. Something I might need to do someday, but doubt you do.

M4RKY N 03-02-2012 05:25 AM

Quote:

Originally Posted by dmax (Post 14141003)
It might be normal, might be a sign that your hose is corroding internally and clogging the valve. Squeeze the hose and if it feels soft and squishy, replace hose...and check inlet to the valve (if you have one) and see if it's clogged. If so, remove gunk...with dental pick, vacuum, whatever.

Also, just read that someone here rebuilt his pump...I assume that means replacing bearings on it. Something I might need to do someday, but doubt you do.

Ok thanks mate, I'll check all the hoses going to it today after work and I'll order some new ones from BMW.
When you say inlet to the valve, where would I be looking or looking for?

dmax 03-02-2012 05:33 AM

Follow the hose from sap out...it goes to the valve...silver thing on exhaust side of engine, with vac hose leaving out the back...assuming, in the UK, you have this pump. The clue, so you know, is that you said the sound disappeared after two minutes...that's how long the SAP runs on cold start, plus or minus a bit.

Drewfus2101 03-02-2012 07:26 AM

Remove SAP.

/problem

Stickbuilder 03-02-2012 08:37 AM

It is right behind the windshield wash tank, which is right behind the clear corner that you probably learned about instead of the proper care and maintenance process that you should have learned about first.

jasonbimmer 03-02-2012 08:42 AM

sounds more like a vacuum cleaner. jets are much MUCH louder.

M4RKY N 03-02-2012 10:56 AM

Quote:

Originally Posted by Stickbuilder (Post 14141251)
It is right behind the windshield wash tank, which is right behind the clear corner that you probably learned about instead of the proper care and maintenance process that you should have learned about first.

So just hearing this sound now equals me not knowing about the car?! :-/
I take good care and maintain all my cars to a very good standard. I just wasn't too sure on which pipes to check, I know there is 2 of them coming out of the SAP but wasn't sure if I was to check the one coming out of the top of it towards the engine head, or the one closer to the front of the car at the bottom of the SAP.

M4RKY N 03-02-2012 10:58 AM

Quote:

Originally Posted by dmax (Post 14141049)
Follow the hose from sap out...it goes to the valve...silver thing on exhaust side of engine, with vac hose leaving out the back...assuming, in the UK, you have this pump. The clue, so you know, is that you said the sound disappeared after two minutes...that's how long the SAP runs on cold start, plus or minus a bit.

I have checked both pipes that are coming from the SAP and one seems a little more easier to squeeze than the other, but there really isn't much difference in the two. What do you suggest? I am able to push either side of the pipe in and they touch each other, but just barely.

M4RKY N 03-02-2012 11:02 AM

1 Attachment(s)
That's the inside of the valve, I have just put a cloth in and wiped around and it's come out with a little bit of dirt on, nothing major

M4RKY N 03-02-2012 11:08 AM

1 Attachment(s)
Also just opened up the SAP lid and it's clean too

jasonbimmer 03-02-2012 11:10 AM

I am not getting what you asking for.
you said it sounded like jet engine so we told you its the sap working.
its supposed to sound like a vacuum cleaner.
if anything, the motor could go bad and you end up with a very loud motor.

jdstrickland 03-02-2012 11:13 AM

Quote:

Originally Posted by Solidjake (Post 14140967)
Yup, the sap. It heats up the o2 sensors

+1, sorta.

The noise is the SAP, but it does not heat up the O2 Sensors.

The CAT uses air and heat to convert fuel into clean air. When the CATs are cold they do not work very well so air is introduced into the exhaust stream. The exhaust stream already has air in it, and there is fuel, but there is no heat to speak of. The absence of heat is countered with more air molecules so the fuel molecules have more to bond to. When the heat arrives, the fresh air can be shut off.

The O2 Sensors heat up because they have internal heaters in them that are turned on. After the exhaust system heats up, the heaters in the sensors are switched off. I'm not sure of the timing of the heaters, but logic says the timing should mirror (more or less) the same timing as the SAP.

M4RKY N 03-02-2012 11:14 AM

OHHH ok. So it's ment to sound as it does when the car starts up from cold.

Sorry my mistake on what I have read

jasonbimmer 03-02-2012 11:16 AM

Quote:

Originally Posted by M4RKY N (Post 14141711)
OHHH ok. So it's ment to sound as it does when the car starts up from cold.

Sorry my mistake on what I have read

yes, to heat up the cat.

jdstrickland 03-02-2012 11:16 AM

Quote:

Originally Posted by M4RKY N (Post 14141691)
Also just opened up the SAP lid and it's clean too

I'm confused. You have been told tht the noise is the SAP, and that it is normal. What are you looking for? Why are you trying so hard to fix something that is working right?

M4RKY N 03-02-2012 12:44 PM

No I was just wondering why it's making such a noise, and from comparing it my friends e46 and his doesn't make the sound at all... So I was just wondering. Also someone above in the thread has said to check certain things so I have done and was just writing back to say what I have found.

jdstrickland 03-02-2012 12:56 PM

Quote:

Originally Posted by M4RKY N (Post 14142087)
No I was just wondering why it's making such a noise, and from comparing it my friends e46 and his doesn't make the sound at all... So I was just wondering. Also someone above in the thread has said to check certain things so I have done and was just writing back to say what I have found.

You ONLY get the Secondary Air Pump on the initial start when the engine is stone cold. If you drive somewhwere and park, then start again before the engine turns to a frozen chunk of steel, the SAP will not come on. If you drive to work and park all day then come out at 4:30, the SAP will start for about 2 minutes.

Some of them make a whine that sounds like a vacuum cleaner, and some make far less noise. The noise is not indicitave of a problem.


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