*** Air Pump Query ***
 

I've never understood the purpose of the air pump ...

What exactly is its purpose?
How important is it?
If it fails...how drastically is performance affected?

As it stands at this time, the air pump is making a "growling" sound as you start the car up and it quiets down about 10-15 seconds after the car starts to idle. I'm sure I'm seeing/hearing the beginning of a problem. I want to take care of this before it gets too cold and I end up getting a call from the wife - stranded someplace unpleasant.

And last, but not least, how many $$$s for either a new, or re-manufactured (if possible) unit.

Thanks in advance for any information.

BTW, this AP is in a '77 280E unit, the engine is the 110.984 series.

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The air pump adds air to the exhaust ports to promote complete combustion. If it makes a noise, the bearings are bad. Look at the 'Buy Parts' link at the top of the page for a replacement, or get another used one from the junk yard. (Look for your car and the part is in the Air Intake section)

http://mb.braingears.com/123_DISK1/program/Engine/110/1977/14-050.pdf

It appears to be a Saginaw (GM) air pump, so availability is good.

http://mb.braingears.com/123_DISK1/program/matrix6.htm

Click on your car.

Yes, it adds air (oxygen) to the exhaust to boost catalytic converter operation until oxygen sensor heats up and controls the fuel mixture for correct oxygen balance.

This only happens initially after starting the engine, and it does have some noise during that time.

Of course, I can't hear wether your noise is usual or not.

<<Of course, I can't hear wether your noise is usual or not.
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What ???

I think he means: Louder than is normally acceptable.