Central Locking Vacuum Pump Specs

[randy48]

For an '82 300 sd turbo, I purchased an identical used replacement pump and it sounds like it works as intended. My question is how much vacuum should it pull to do the job on the doors, fuel flap and trunk? It will operate the trunk and fuel flap fine. In tracing and testing the lines, actuators, and connections, with a minivac, it appears that it does not have enough power to move the door locks. After isolating then I can operate them with the hand pump individually, but the pump will not close them, even after lubrication.

Hooked Directly to the handvac (from HarborFreight), it pulled 15 inHg but dropped to zero immediately.

Thanks in advance for help or guidance to info/sites.

[toomany MBZ]

it should pull around 20 inHg at sea level, less at higher altitudes. Make sure you test each orifice independently and plug the other one off. One will have less vacuum.
The SD chassis has a separate door, trunk, fuel door lock system. A pump in the trunk.

[randy48]

Turns out the R/R actuator had a leak. I missed the leak when I used the handvac because it closed the lock. Found it when connected directly from the pump to the actuator and heard the hiss. Will try to re-seal the diaphram. It appears to have come loose -no hole. We shall see.

Thanks for your response.

[toomany MBZ]

Glad you found the problem, that at least half the battle, good luck, let us know how it turns out.