I recently bought an '83 Turbo-Diesel. It is my first car and I love it. It has a problem with it's power locks; they don't work. Any known explanations? I've heard that this is a vacuum problem. I'm pretty new to things like this so any help would be appreciated!!!

Klaus -

Did you say your first CAR, or your first MB diesel? Either way you're welcome on this board, but if this is your first CAR we know your parents raised you well.

As a registered member you can use the search function. Use it and you'll find most of the answers you're looking for. You can also use the advanced search function on Google, limiting the domain to be searched to peachparts.com.

One of the things you'll learn is that vacuum controls many things on these cars, including the door locks. Diagnosing a vacuum leak can be time consuming, but it's a wonderful opportunity to bond with your new car.

The basics:

- On the front of your engine is a vacuum pump. Identify it by the large black plastic tube running to the brake booster. With the engine running, this device provides vacuum to operate and control your power brakes, transmission, door locks, and other subsystems. Inside the pump is a rubberized diaphragm that can rupture. The pump can be rebuilt, but if you're a novice you might not want to try this by yourself.

- In addition to the main vacuum line going to the brake booster, you'll find a maze of small, hard plastic vacuum lines, typically white with colored stripes to identify their function. These can become brittle with age and crack. They're cheap to replace.

- The small vacuum lines are connected with various rubber T's, Y's, and X's. These definitely become hard and crack with age. Also cheap to replace.

- Inside each door (as well as the trunk and fuel filler door) is a vacuum-controlled actuator. Inside the actuator is a rubber diaphragm. (You know where this is going.) These are less cheap to replace, but you can find used ones.

- Somewhere on the car (probably in the trunk, under the rear deck lid or "hat rack" as MB calls it) is a plastic vacuum reservoir. This stores vacuum when the engine is off so there's vacuum available to open your door locks later. It can crack. On the W126 chassis, beginning in 1982, Mercedes replaced this with an electric vacuum pump that operates just the central locking system. I'm not sure when (if ever) Mercedes added an electric pump to the W123.

If you plan to keep this car, buy yourself a MityVac, a handy little tool to test vacuum lines. Some troubleshooting can be done without one, but it will make your job a lot easier.

Good luck.

pjc