Vacuum diagnostic help - 77 240d 4 speed manual
 

My calipers are sticking, and someone here suggested it could be the vacuum pump as a culprit, so I am trying to check out my vacuum pump. This scenario makes sense for me, because as long as I've had the car, I've never had the car shut off with the key, I always have to kill it by letting out the clutch (sorry if reading that makes you cringe).
So, this may make me the newest recipient of a dunce cap, but can someone look at my photos here, and tell me if I'm testing the vacuum pump right, more specifically, is this ACTUALLY the vacuum pump? It doesn't look the same as any of the pumps I've seen pictures of.
This first picture shows me replacing the hose with the mityvac,Camera+ photo http://campl.us/f5huegKRkBM The second one I use a 3 way connector and keep the hose connected, http://campl.us/guuG8vtGcM0 Camera+ photo
And the third photo I just want to make sure - if you look closely you will see a connecting part with no hose attached (the hose is on the right, if you look towards the bottom of the presumed pump there is a connector begging for a line. http://campl.us/gvg9BPFBlV6http://campl.us/gvg9BPFBlV6

I'm getting a zero reading on my mityvac, which is why this isn't just self explanatory for me.
Please help!
And feel free to call me out if I am completely lost, I've never attempted anything with the vacuum system.

Sticking calipers are not caused by the vac pump. Stuck calipers are usually caused by seized pistons inside the caliper itself or degraded brake hoses. The brake hoses swell up when they are going bad which doesn't allow the pressure to bleed off after you release the brake.

You shutting off problem is vacuum related. It could be a leak somewhere in the system, a bad shut off valve, or a bad vac pump. To test your vac pump you need to unplug all the hoses coming off the main vac line from the pump to the brake booster. Then hook up your mity vac. If you have two ports on the main vac line plug the one you're mity vac isn't using. Then start the car. You should get a reading of above 20"Hg. If not than either your pump is in need of a rebuild or the booster is leaking. From here you can remove the line off the booster and plug it and take a reading again with the car running. If the vac jumps up then the booster is leaking, if nothing changes than the pump needs attention.

You can also test the shut-off valve itself using your mity vag. Plug your mity vac directly into the shut-off valve. Then start the car. Then pump the mity vac. It should only take 1-2 pumps to shut the car down. If you have to pump more than that the valve needs replacing.

You're hooked to the shut off valve in that picture. If the engine is running and you suck a vacuum on that with the Mity Vac the engine shut shut off if the shut off valve is functional.

I've seen the argument on here elsewhere as to whether or not the vacuum can cause the calipers to stick, people seem to be 100 percent sure it can cause it and others are 100 percent sure it can't cause it. I just want to rule out the vacuum pump as the cause, so I can move on to getting a little dirtier with the calipers.
So if I have it connected to the shut off valve, then where the devil is the vacuum pump located?
I can't seem to find it anywhere.

Follow the Big Black line from the Brake Booster towards the front of the engine. connects to a metal line, other end of that line connects to the Vacuum pump on the Left front of the engine.

Charlie

Thank you for clearing that up Charlie. I followed Andrew's advice and am happy to say my pump is working nicely, not so happy to say I have a leak. If anyone knows a common culprit for leaks I would be glad to hear it! I'm not thinking it the cause of my caliper malfunction anymore, but it would be pretty neat to have a car that shuts off how it should. Oh and thanks Kerry for the shut off valve info. If only all forums were as great as this one!

There is no way vacuum can cause a caliper to stick. I have read an awful lot of posts over the past six or seven years, and have never read that one. The only thing that can cause a caliper to hold is either your foot on the pedal, then assisted by vacuum, and a situation where the brake fluid can not get back to the master cylinder due to a blockage in the hose. There is no vacuum connection to the brake system except at the vacuum unit behind the master cylinder and then you get assistance as you press the brake pedal.

I found the thread where I got that impression, http://www.peachparts.com/shopforum/diesel-discussion/300280-brake-problems-question.html

If you scroll down to Andrew's post, this is where I got my info. But since he said earlier in my thread that the vacuum pump can't cause the calipers to stick, I'm pretty sure I misinterpreted it completely. And where I mentioned the debate about whether or not it can be the cause, I was actually thinking of the debate as to whether or not a failed hose could cause the stuck calipers.
I did my research months ago, so I apologize for being a little confused.

With only 130k on your 240D it does appear that simple routine maintenance is being overlooked. Your car is easier to work on that a 300D.

If you need help just ask here but please get it done.

The vac pump can and does affect braking. What I was describing in that post was a lack of vacuum which causes the loss of the power assist brakes, which makes the brake very hard to use. You have to apply the brakes extremely hard to stop.

The hoses probably don't directly cause a seized caliper, but what they will do it cause the calipers not to release completely which causes the brakes to drag. Which will cause the rotors, pads, and calipers to overheat, which can cause the calipers to seize up. The best way to check your calipers is to pull the wheels and try to get the brake pads out. If you can't squeeze the pads away from the rotor without a ton of force then the caliper is seized up. You should be able to push the piston of the caliper flush fairly easily, if it takes a lot of force than it's seized up.

Thanks Andrew, that makes sense. I don't think they are seized up; in the little driving I've done since this happened it seemed they would stop dragging after a bit and then start again after I applied the brakes. I am planning on ordering brake lines and replacing them and going from there.

Gee, thanks. After my father's passing I've really been looking for someone to fill the void. I will look you up whenever I need a reminder of my own inadequacy.
In all seriousness though, your comment was unnecessary and inappropriate. Let's try to keep things civil here, shall we? You know nothing about me and thus are ill placed to make assumptions of my character or my willingness to maintain my car.

My comments were not meant to be malicious only as hopefully a positive direction to take.

Ok then I'm sorry that I interpreted them as such.

I reread my post and see how easily you could have.

On to fixing your Benz !