My locks aren't holding vac after shutoff. This problem started all of a sudden. After I shut off the car I can hear hissing under the dash which changes intensity with lock/unlock of the doors. It's very difficult to see under there let alone get my hands up to follow the lines. I've traced the lines as well as I could with my hands and there don't seem to be any loose connections. I couldn't find any old posts with the hissing under the dash symptom.

Oh, forgot- all vac is gone after sitting any longer than 5-10 minutes.

I can feel a check valve or something in-line but I can't get it moved over to see what color it is. Do these symptoms sound like that valve is bad?

Thanks,
-T-

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'83 240D

If you are out in the country check to see that the hissing is not a snake...LOL

As far as I know you ... or some little skinny person... is going to have to turn upside down with a flashlight and probably take some lower kick panels off to see and do any good up in there... I was going to recommend you get a simpler car...but I see you also have a 240d... so you are going to have to bite the bullet and search closer....

These cars are OLD... rubber and plastic just gives way at some point... might be just as easy to go for replacing the whole line than finding a specific crack... it may crack someplace else next month if you leave it in there...

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1980 240d ,

chain elongation, cam marks reference:
http://www.peachparts.com/shopforum/showthread.php?threadid=10414

http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html

evap fin cleaning:

http://www.peachparts.com/shopforum/showthread.php?t=156207&highlight=evaporator

A/C thread

http://www.peachparts.com/shopforum/diesel-discussion/297462-c-recommendations-mb-vehicles.html