1979 450SL - Air Slide Valve Operation/Check - Mercedes-Benz Forum

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post #1 of 1 (permalink) Old 05-05-2011, 07:12 AM Thread Starter
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Date registered: May 2011
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1979 450SL - Air Slide Valve Operation/Check


I have removed the air slide valve from my car (Bosch 0280140), and tested it (I think) by immersing it in hot water. I noticed only one air port did indeed attain an almost fully closed position (open maybe 1/16 inch) when heated, and opened when cooled. The other port, regardless of temperature, remained fixed at a half-open/closed position. Is this normal operation?

Should both sides of the ports have opened and closed equally?

Also, on the "stuck" port, the upper portion of the sleeve where the pistion slides appears damaged/rough edged.

SYMPTOMS of car: Good cold start; as engine warms, idle decreases continuously until engine surges, almost stalls. In fact, engine has stalled, but not always, after driving and coming to a stop, especially with AC on, and engine temps. near 212 (I live in Arizona, where almost everything is always 212). Engine sometimes diesels a little upon shut down, especially when hotter.

Could faulty air slide valve (too much air) also be a reason for the car to be running warmer than normal?

If it is a faulty air slide valve, can anyone recommend where to get one? I've seen them listed on e-bay for about $150.00 (refurbished?), and brand new for $370.00. Either way, yikes.

Thank you for your help,


Last edited by Berdo; 05-05-2011 at 07:16 AM.
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