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  #1  
Old 12-21-2002, 02:15 AM
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Location: Austin, Tx
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Airpump disconnect...

Hello everyone! I believe my air pump is going south as evidenced by a loud screeching sound that comes around for about 30-40 seconds after I start up the car. It sounds like a turbine spooling up actually, except really high pitched. I was wondering if anybody knows how the ECU tells the air pump to turn on and if it were possible to just cut this wire and not have the pump activate? I have a 1992 300E with old school Cis-E, so I don't have to worry about the car spitting out error codes or even a check engine light...Thanks!
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  #2  
Old 12-21-2002, 02:53 AM
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My air pump went to lunch on my 86 Euro 500 SE I removed with no ill results I belive it's only ingages for about 30 second on cold start up. check search on it as I post same question. I live in a part of OR. that has no emmission check so might be tecnicaly a no no in your state.......
William Rogers.........
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  #3  
Old 12-21-2002, 11:24 AM
DHA DHA is offline
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Join Date: Jul 2002
Location: Atlanta
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There are some recent threads on this topic. I had this problem of noise, etc. on that A.I.R. pump. From this site I gathered that the pump really is not needed and serves no purpose beyond the first minute after a cold start. Examining the pump in-place (560SEL) it could be seen that the pulley/clutch assembly was not functioning--pieces actually fell out. I cut the drive belt. Noise problem stopped. Car runs OK since. Recently I asked Donnie of MB Motor Werks (this sites sponsor) if there could be adverse consequences for disconnecting the pump. Reply was that unit only works for that few seconds following a cold start. No mechanical consequence.
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  #4  
Old 12-21-2002, 03:58 PM
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Simply disconnect it at the right fender area unless you're concerned about the pristine air in Austin. Like the above poster noted, it only spins for the first 30-45 seconds (when temp needle hits first peg above 40) so I don't think even the most environmentally sensitive would be offended.

Just make sure your car is fully warmed up next time you go in for an inspection -- that is if Austin has smog checks now, not sure if they do.... here in Houston it's required. I disconnected mine, and didn't get a CE light, but do have a stored fault code, but due to a vacuum line disconnected I think.

G'luck
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'01 E430, Sport 72,000 mi
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Last edited by pmizell; 12-24-2002 at 02:48 AM.
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  #5  
Old 12-21-2002, 06:29 PM
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Location: Joliet Illinois
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Air Pump

I removed an air pump that went out on my Volvo and put over 120,000 more miles on it without any ill consequences. If the pump goes out on my 300e I will do the same.

I believe the air pump on your M103 is driven by the serpentine belt. If you want to completely remove the pump you may have to put a smaller serpentine belt in. I have an '92 300e with an air pump and a '88 260e without one. A belt for a '88 260e from Fastlane it should fit your engine once the air pump is off. The only other thing you will need to do is plug the hoses real good.
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  #6  
Old 12-21-2002, 06:44 PM
M D Nugent
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How they work and why it doesn't matter

Not sure about MBenz in particular, but most such air pumps pump air (duh) into the exhaust right after the exhaust valve. The theory is that any unburnt hydrocarbons (especially if they were unburnt as a result of too rich a mixture) will burst into flame when exposed to an oxygen source since they are so hot (~1400F).

This is basically a burn-off of exhaust - outside the combustion chamber - so it adds no power when present and takes away none when it isn't operating.

The only downside I can think of is that if your mixture is too rich and the air pump doesn't burn off the unburnt hydrocarbons, they'll end up in your catalytic converter (if you have one/more) and that will shorten the life of the expen$ive cat(s).

Unless the belt that drives the air pump drives something else in addition, why not just remove the belt?
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  #7  
Old 12-21-2002, 09:14 PM
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Thanks a bunch guys. I was hoping I could just mess with the wires going to the pump, because something has to tell it to deactivate, and I was thinking I could just rig it up so it stays off. Does anyone have any knowledge of how the airpump is turned off and on? The only reason I don't want to remove/cut the belt that runs it is that I might be moving to either coast for college, and I would hate to fail my emissions test, and since the pump still works, albeit loudly, I might as well save it for the smog check...
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  #8  
Old 12-21-2002, 09:52 PM
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You don't need the AIR pump for a smog check, if you're engine is warmed up. The pump only activates for a minute at most during cold starts, to reduce emissions ... then shuts down.

After that, emissions aren't affected one way or the other with or without AIR pump. Follow the electrical line coming off pump and you'll find the two pin connection near the right fender/wiper resevoir area and disconnect it.

I would add a disclaimer here, but I don't envision the EPA knocking on your door to check your AIR pump connection anytime soon.
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'01 E430, Sport 72,000 mi
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Last edited by pmizell; 12-24-2002 at 02:47 AM.
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  #9  
Old 12-22-2002, 01:49 AM
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thanks!! Ill do it first thing in the morning! (Although I am having second thoughts, the thing sounds like I have a turbo the size of a watermelon churning under the hood hehehe)
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  #10  
Old 12-22-2002, 11:33 AM
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Some things to consider before you disable a smog pump. Most state emission inspections check that certain emissions components, including the smog pump, haven't been tampered with. If the inspector knows what he's doing, he will be looking for missing belts, plumbing or wiring related to the smog pump.
If you disable the smog pumps drive clutch or belt, and the pump is still connected to the emissions plumbing, trace amounts of fumes or moisture will get into the pump causing it to seize. Chances are, if the pump drive is disconnected, by the time you reconnect it for emissions testing, the pump will be locked up.
(Although, you could wait until the engine is warmed up before plugging in the wire connector, if at that time the pump isn't engaged anyway. The belt and pulley would still turn even if the pump was locked.)

Happy Motoring, Mark
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  #11  
Old 12-22-2002, 11:53 AM
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Hey thanks Mark, that is some good information to know. I think I will end up disconnecting it anyway because if I don't, ill end up buying a new one, so I guess ill just take my chances with the emissions tests (there are none in Austin) and if I don't pass, ill just shell out for a new one at that time.
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  #12  
Old 12-22-2002, 03:13 PM
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Location: Joliet Illinois
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Disconnecting Air Pump

I agree with Mark, if you just disconnect the air pump it will probably sieze up totally in a short time. That happened when I removed the belt from the air pump on my Volvo to test the source of the noise. I didn't hook the belt back up for about a week and when I did, the air pump would not turn at all. At that point I was faced with the decision of getting a new air pump or just going without. I chose the latter.
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  #13  
Old 12-22-2002, 05:08 PM
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hrrmm... so you think I should clamp off the hoses as well? Would that do the trick?
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  #14  
Old 12-22-2002, 08:21 PM
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The best thing would be to disconnect and plug the air hose at the back of the smog pump and also plug the air nipple on the pump, but now, you see, it's no longer as simple as just unplugging the pump wiring.

Happy Motoring, Mark
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  #15  
Old 12-23-2002, 04:25 PM
inspector1
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Thumbs down

I can not and never will understand why some of you guys will go to the trouble of driving the worlds finest automobiles, then "fix" a problem by tearing it out or disconnecting it.

As far as the emissions testing, if the vehicle fails, you will never get it registered without the air pump, legally.
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