PeachParts Mercedes-Benz Forum - How fast should vacuum build?

Your test of both nipples should have behaved the same, i.e. vacuum should build in about the same time. The fact that the second nipple test took longer to build vacuum is a red flag and I would investigate further. Something was leaking during the second nipple test.

Did you plug the main vacuum line where you disconnected the yellow and HVAC lines?

Quote:

Originally Posted by tankowner (Post 2766204)

Okay, some new details have emerged. I believe part of the problem is that the lines have been hooked up wrong since I bought this car (yes, I have slowly been working on it . . . a long time, but I am nearly ready to put it on the road, so I need to get this shut off deal resolved).

Okay, so there are two nipples off the main vac line that runs to the brake booster. The one nearest the pump is labeled 0.6 and the one nearest the booster is labeled 0.5. Looking at a diagram for the '83 manual 240D, I see that 0.5 line (nearest the booster) should run to the green dashpot. Assuming that is correct, then the lines coming off the main line were switched. (Apologies to winmutt, if this is what you meant - I was thinking the lines at the key switch.)

So, I also did a little more testing. Turns out that the vac coming out of the pump is good - it pulls 22" immediately. If I block all the lines off except the brake booster itself and then put the gauge on the first nipple (nearest the pump - or 0.6), I get 22" real fast. However, when I block off the first nipple and test only the second (nearest the booster) it takes a long time to build up. (This is what led to my original question - how fast does vac build? - and also what created the several minute lag before the engine died after turning off the key).

SO . . . now I have the brown vac line hooked to the first nipple (nearest the pump). I have the yellow lines disconnected (too many lock leaks) and also the HVAC line disconnected (seems to add a couple seconds to shut off). The big news is that I can actually shut the car down with the key now. Of course, that still leaves me with some problems/questions.

Shouldn't I still be pulling decent vac out of the second nipple (nearest the booster)? I stuck a wire in there to see if it was clogged, but it didn't improve. Also, looks like I have some oil in some of the vac lines. The shut-off actuator will hold vac, but from other searches, it looks like it can still work while leaking oil. Any other potential sources for oil in these lines?

Thanks.