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Q: Power Locks on 1991 Mercedes-Benz 300SL

When I push the key fob to lock the car... I can hear the noise like it's trying to lock everything but it doesn't lock. Any thoughts?
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Well we have the same problem on ours. I'm pretty sure it's a vacumn problem. These door locks all work using vacuum systems. The car willnlick when manually locked but when you use the fob and you hear it trying to lock it is probably lost vacuum and cannot build enough pressure to re-lock. Only fix is to go thru all the vacuum systems until you find the leaky hose or gasket somewhere and replace it. These cars are old, and they constant jiggling of driving will cause the vacuum hoses to rub against metal edges causing it to leak. Take it to a Mercedes dealership and theylle do it. It may be expensive, but you want your doors to lock right?

Hope that helps brosef!
I had the same problem with mine,so I tore the pump out (its in the trunk ) and then opened it up and found two internal hoses off,so I reattaced and used small zip ties and alls well
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