My recently acquired 1980 240d has been sitting for years and had a perfectly functioning vacuum system when parked,
Now...it has weak vacuum, brakes are harder than they should be and occasionally the vacuum light will flicker. The brakes work better as the revs are kept up.

Where do I start to looks for leaks? I will replace all the ''tees'' in the vacuum lines and will plug the door lock vacuum system to eliminate that whole area.

The previous owner said he would occasionally replace the "diaphragm" on the end of the vacuum pump...the device that has two vacuum fittings on it and screws onto the pump itself. The two fittings go to the brake booster and the air cleaner.

What is this device actually called? could it be bad?

 

Ok, thank-you. Upon further research, it is the brakes pad wear light that is flickering.

 

So I pulled the pads off to see how they were....they were toast. took the calipers off to and the front ones both have one stuck piston.

 

Ok I'll do that. Thay were sure a pain to get off....probable a good thing though. haha

 

Got 4 new Bendix calipers today. for just over $100 a piece.

When I put it all back together, can I get rid of the pad wear indicators? I would much rather have it out of the way for good.

And any tricks to bleeding such a large volume of air out of the system?

 

To bleed the brakes, if you don't have the stuff they have in most shops, have an assistant pump the brake pedal till you get a firm pedal, then hold pressure on it while you crack the bleeder screw, DON'T LET UP ON THE PEDAL TILL YOU TIGHTEN THE BLEEDER SCREW BACK. Repeat the process till you get clear fluid at all four wheels. Work starting at the right rear then left rear then right front then left front.this works the air out of the longest lines first. Remember to keep the master cylinder full while doing all of this.

 

Good info, thanks.
Now im thinking about doing the front ones firsrt, then driving it for a couple days and will do the rears on the weekend. If I only do two at a time, would I still have to bleed the two that I didn't touch?

Thanks again

 

Ok, the sensors ar coming out. I will cut and tape the wires.

 

New calipers on now.
I can't seem to get the front calipers bled, got the rear ones bled until there is a solid stream of fluid coming from the bleeder screw. However, the pistons are not contracting yet......

But I can't even get a trace of fluid to the front calipers. I did the rears first.

 

I am not building any pressure at the pedal. I can pump all day and it still goes to the floor with the engine running or not.

Is the master cylinder toast? could there be a stuck check ball or something in the master cylinder?



Any tips?