I use to be able to lock and unlock all the doors, trunk lid and fuel door, on average about 5 to 8 times after the engine has been turned off. I am now down to about 2 times due premature loss of vacuum.

I will be replacing soon the leaking Shutoff valve at IP (evidence of oil in the vacuum line, luckily captured by the pre-filter I installed like Thomaspin) and I’m wondering if the two are related or coincidental? Should I look anywhere else? I have a MityVac and will be troubleshooting for vacuum leak.

Your $0.02 is appreciated.

There should be a check valve that isolates the lock system from all other vacuum consumers. It has three ports - 1 on one side and 2 on the other. The single port goes to the vacuum supply, while the two ports go to the vacuum reservoir and the lock circuit. If this is connected properly and the check valve is working, then the door locks would not be affected.

Now that I've just typed all that, if the shutoff is leaking so bad that you're not achieving maximum vacuum in the reservoir, say only 10" instead of 20+, then yes everything would be affected.

__________________
Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

Additionally, the shut-off valve should be isolated when the car is in the run possition by the valve in the key switch. If your system was suckign oil through the shut-off valve, perhaps flushing the lines and replacing the connection at the key switch would be good, too.

I recently bought a shut-off valve from Performanec products, and it had "Ronak" on it, and it was DOA. It didn't hold any vacuum and trying to pump it wouldn't even budge the arm. The reason I didn't order it from here is that the website said that they weren't available. Of course I determined this after I installed it. From this I learned to check every part I get before I put it in.
Have fun,
Adam

Rick: Is the check valve the "yellow" thing with the yellow vacuum line?

Adamb: the "ronak" shutoff valve I received seem to hold vacuum. See thread: Shut-Off Valve @ IP aka Vacuum Control Unit or MB FSM-EPC = shutoff box

Yes, the 3 way check valve is yellow. Im also working on a vacuum shutoff problem, which i believe is almost solved. BTW, Phil does have them, its a PartsShop item,
# 000 070 20 53 ...its 43.00

How's your brakes? I searched for a vacuum leak which kept getting worse. In addition to the shut-off valve my brake booster was leaking. Gradually got worse and worse. Vac bled off slowly til I hit the pedal and then it would just plummet. Because it happened slowly I did not realize how firm my pedal had gotten until I got another 123 (which donated the booster in addition to the engine).

__________________
andy t
'78 300d
'95 volvo 850, wagon
'86 300sdl - engine out, maybe I'll have it rolling by June

whole bunch o' bicycles

Guru, I think my brake booster is the culprit as well! when I take the main vac line out of the booster and plug it with my thumb, the car will shut off! I also have to replace the IP shutoff valve again because the one i got from Phil was unfourtunatly defective. It took several pumps to pull the arm closed, while a good one will pull it closed almost immediately.

ALL functions appear to be normal other than the premature loss of vacuum noticeable by the door lock issue I have currently.

I have so far replaced the loose 4-way rubber connector to the check valve and have ordered a check valve from the dealer.

FWIW, all these symptoms and malfunctioning started when I noticed oil in the pre-filter I installed in the shutoff valve vacuum line. I will be having the leaky shutoff valve replaced by a garage (concern about the runaway engine) soon. See what happens and hopefully should fix the problem.

Installed a filter on the line, recommended.

Attached Thumbnails

 

I just purchased a "ronak" shutoff valve, using the MityVac, it takes two full pumps to fully-retrack the lever and holds vacuum. See photo: Shut-Off Valve @ IP aka Vacuum Control Unit or MB FSM-EPC = shutoff box

Exactly! We also went to a local dealership and tested one there, it also fully closed with 2 good pumps. WM20650 is my brother and were working together on this car, see my sig.

Rick:

Your troubleshoot of my problem is correct. I just had the Shutoff Valve at IP replaced today and my door locking/unlocking functions are back to normal (about 8 times before I exhaust the residual vacuum after the engine has been stopped).

BTW, I tested the old leaking Shutoff Valve and the lever fully-retracted after two full pump strokes on the MityVac (still able to shutdown the engine) but does not hold vacuum.

Thanks for the help.

I seem to loose vacuum (for the door locks) more rapidly when the car is outside on a cold day as oppose to when the car is in the garage. There's only enough vacuum to last the locking and unlocking of the doors for about 3 times post-engine shutoff.

I have just replaced the check valve (yellow) for the door locks and shutoff valve. I don't believe that there is any further vacuum leak in the system as it locks and unlocks all the doors about 8 times post-engine shutoff when it is inside the garage.

Awesome! I'm glad that you fixed the leak finally!
Pease do keep an eye on the Ronak shut-off valve as I had three that went bad within a week even though they tested OK when new. There was nothing I did wrong and when I called to get an RMA, the rep said they have experienced numerous problems with them.
Good luck,
Adam

Well, the system depends on rubber connectors to join the hard plastic vacuum lines, and those connectors must remain pliable to form a seal. I could see them becoming stiff and leaking a bit in really cold temperatures. Of course, being in Vancouver, your definition of cold is much different than mine!

__________________
Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

1984 300DT

So far I have replaced all the visible rubber (3) 3-way, (1) 4-way and (1) yellow check valve vacuum fittings in the engine compartment in hope to cure the premature loss of vacuum for the door locks, but to no avail.

Referencing the vacuum diagram in the CD manual indicates that there are some more 3-way and 4-way rubber fittings (distributors) inside the car but where? I am trying to find the location of these distributors so I can hook-up a MityVac. Where should I be looking? Is it necessary to remove the door panels? I see vacuum lines under the front floor mat but no distributor.

Your help is appreciated. Thank you.