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1982 300D
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8 Posts
Discussion Starter #1
I've searched this issue and can't seem to find the info I want. Our 82 300D with 270k on it won't consistantly lock the doors and shut off when it gets hot outside. I've concluded that the master vacuum/element switch on the driver door may be causing some of the problem. In further testing the main green line to the climate system shows a slow leak in the system. I pulled 15" with my Mityvac. After about half hour it went down a few inches. As I moved to the actuator pods I went up to 20". After half hour or so the first few pods I have tested so far went down a couple of inches. When running the car all the pods seem to function the vents properly. I isolated or blocked off the door locking system by putting a guage in that vac port so I could watch the vac while engine was running. After start up it takes a minute or so for the vac to get up to about 22". When I push a button on the climate control panel The HG drops to about 4" and then takes about a minute or so to build back up to about 22". When I go to shut off the car it takes at least 4-5 seconds for the car to shut down. I have pulled vac on all the other vac components including the shut off valve and all seem to hold vac good. I pulled hose to shut off valve. It holds vac and no oil in hose. With engine running and Mityvac hooked to shut off valve it only takes about two pumps and engine cuts right off. My question is how much vacuum do you pull on the various components and how long should the hold? Is there an acceptable amount of leakage espically the actuator pods or switchover valves. Is there an accepted DIY troubleshooting procedure to go thru the CC vac system. I don't want to go thru the trouble of fixing the pods if its not necessary. Thanks
 

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Registered
1982 300D
Joined
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8 Posts
Discussion Starter #2
Following up on my post. I spent some of the weekend dignosing this issue. Number three switchover valve and pod in the climate control system had slow leaks in them. Considering what they did or maybe better put what they didn't do, I blocked them off from the system. Wife said she would like to have heat come from the center vents anyway. We can close them off when needed by shutting vents. I pulled a vacuum on the pod to open it then installed a screw into the ductwork to hold the flap open. I put the screw along the edge of the flat section of the white plastic piviot point for the flap. This acts as a pin to stop the flap from pivoting. Much easier and better to me than the zip tie method. I am left with a couple of questions now. There are two master vacuum switches/elements for the driver door available. Our driver car had a black one in it. Our parts car had a white one in it. The black one has a short body with a long linkage and the white one has a long body with a short linkage. Besides the lengths of the body to linkage combinations is there any differance between them because the black one is about three times the price as the white one. I suspect both the ones I have are bad so I want to buy a new one so if there is no other difference I'll get the cheaper white one. I checked the CVC valve on the IP. With engine off it stops pulling vac at about 13hg and then leaks slowly down to about 9HG in about 5 min. Is this slow leak acceptable for the CVC? I've read many sources about how to adjust them and how to check for leaks, but not what constitutes a leak. One article only said that the CVC should hold a vacuum for 5 min. Thanks
 
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