Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 03-23-2012, 10:05 PM
Registered User
 
Join Date: Sep 2006
Location: Midwest
Posts: 66
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 The second one I use a 3 way connector and keep the hose connected, 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/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.

__________________
1977 240d 4-speed ~200k
Reply With Quote
  #2  
Old 03-23-2012, 10:20 PM
Biodiesel300TD's Avatar
|3iodiesel300T|)
 
Join Date: Dec 2004
Location: Albany, OR
Posts: 4,845
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.
__________________
Andrew
'04 Jetta TDI Wagon
'82 300TD ~ Winnie ~ Sold
'77 300D ~ Sold
Reply With Quote
  #3  
Old 03-23-2012, 10:30 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,355
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.
__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13
Reply With Quote
  #4  
Old 03-24-2012, 10:17 PM
Registered User
 
Join Date: Sep 2006
Location: Midwest
Posts: 66
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.
__________________
1977 240d 4-speed ~200k
Reply With Quote
  #5  
Old 03-24-2012, 10:26 PM
Registered User
 
Join Date: May 2007
Location: Out in the Boonies of Hot, Dry, Dusty, Windy Nevada
Posts: 9,585
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
__________________
there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works
Reply With Quote
  #6  
Old 03-25-2012, 12:21 AM
Registered User
 
Join Date: Sep 2006
Location: Midwest
Posts: 66
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!
__________________
1977 240d 4-speed ~200k
Reply With Quote
  #7  
Old 03-25-2012, 03:25 PM
junqueyardjim's Avatar
Registered User
 
Join Date: Apr 2005
Location: Cicero, Hamilton County, Indiana about 30 miles north of downtown Indianapolis
Posts: 2,621
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.
__________________
Junqueyardjim
Christianity, if false, is of no importance, and if true, of infinite importance. The only thing it cannot be is moderately important. C.S. Lewis



1983 Mercedes W123 240D 4 Speed 285,000 on the road with a 617 turbo, beautiful butter yellow, license plate # 83 240D INDIANA

2003 Jaguar Type X, AWD. beautiful, good mileage,
Mom's car, but I won't let her drive it!
Reply With Quote
  #8  
Old 03-25-2012, 04:20 PM
Registered User
 
Join Date: Sep 2006
Location: Midwest
Posts: 66
I found the thread where I got that impression, Brake problems, and question

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.
__________________
1977 240d 4-speed ~200k
Reply With Quote
  #9  
Old 03-25-2012, 05:19 PM
TnBob's Avatar
Registered User
 
Join Date: Dec 2009
Location: Shelbyville, Tn
Posts: 1,907
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.
__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."
Reply With Quote
  #10  
Old 03-25-2012, 09:08 PM
Biodiesel300TD's Avatar
|3iodiesel300T|)
 
Join Date: Dec 2004
Location: Albany, OR
Posts: 4,845
Quote:
Originally Posted by Nordon View Post
I found the thread where I got that impression, Brake problems, and question

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.
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.
__________________
Andrew
'04 Jetta TDI Wagon
'82 300TD ~ Winnie ~ Sold
'77 300D ~ Sold
Reply With Quote
  #11  
Old 03-26-2012, 11:57 AM
Registered User
 
Join Date: Sep 2006
Location: Midwest
Posts: 66
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.
__________________
1977 240d 4-speed ~200k
Reply With Quote
  #12  
Old 03-26-2012, 12:05 PM
Registered User
 
Join Date: Sep 2006
Location: Midwest
Posts: 66
Quote:
Originally Posted by TnBob View Post
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.
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.
__________________
1977 240d 4-speed ~200k
Reply With Quote
  #13  
Old 03-26-2012, 12:41 PM
TnBob's Avatar
Registered User
 
Join Date: Dec 2009
Location: Shelbyville, Tn
Posts: 1,907
My comments were not meant to be malicious only as hopefully a positive direction to take.
__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."
Reply With Quote
  #14  
Old 03-26-2012, 12:45 PM
Registered User
 
Join Date: Sep 2006
Location: Midwest
Posts: 66
Ok then I'm sorry that I interpreted them as such.
__________________
1977 240d 4-speed ~200k
Reply With Quote
  #15  
Old 03-26-2012, 10:59 PM
TnBob's Avatar
Registered User
 
Join Date: Dec 2009
Location: Shelbyville, Tn
Posts: 1,907
I reread my post and see how easily you could have.

On to fixing your Benz !

__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 12:17 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page