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-   -   air injection pump makes noise when first start car (https://mercedesforum.com/forum/general-tech-5/air-injection-pump-makes-noise-when-first-start-car-10584/)

varval 04-06-2006 12:49 PM

air injection pump makes noise when first start car
 
hey i have this 1993 400 sel. car runs great but last two months when it is cold and upon starting i usually hear this noise on the rite front of the motor . i checked it a week ago and i saw that it is the clutch on the air injection pump that engages. i need to know what is causing this. is there some type of servicing that i have to do on there.

varval 04-06-2006 12:54 PM

1993 400 sel radio
 
it is a 1993 400 sel also i need to change the sound system on this car. my original radio is beging to raise the volume and regulate the volume by itself. i need to know if there is any interface wires or jacks that i can use becasue i do not want to cut the wires. i like the sound in the car. but i am thinking of going with an alpine navigation and two head rest monitors. please anyone out theree with info. oh also i will change all the speakers in theree as well any tips.

Lugnut 04-06-2006 03:44 PM

RE: air injection pump makes noise when first start car
 
The AIR pump only runs during a cold start, before the O2 sensors and everything else smog-related warms up and passes self-testing. It runs for a minute or two, usually. It makes a slight supercharger-type of whining sound. Are you saying it's making an unusual sound?

The radio volume may be speed-sensitive. That is, the volume raises as the car goes faster. It compensates for road noise. If this is what you're talking about, check the owner's manual for the radio on how to adjust or disable it.


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