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 01-20-2010, 01:28 AM
Registered User
 
Join Date: Sep 2007
Location: Bakersfield
Posts: 216
85 300SD Vacuum Lines Broken

Was finishing up a valve adjustment and happened to notice that the plastic line that supplies vaccum from the intake manifold was broken right at the connector that goes into the manifold. OK, better fix this...

The line is a hard, clear plastic line. It is very hard and the portion that is broken still over the nipple will probably need to be cut off to get it off.

Questions:

-Do I need to replace it with this hard line or can I just use the black, flexible vaccum hose? Maybe this stuff used to be flexible, and it hardened over time, but not sure. Since it is transparent-yellowish, I suspect it is different and maybe withstand high temp better or something.

-With this line broken, doesn't this mean that I virtually had no vacuum? Wouldn't this have caused very noticeable issues? Car seemed to be running fine before, so maybe the line got cracked from the work I was doing. What symtoms would a person see with little to no vacuum? Loss of power brakes, tranny problems, etc.

Thanks guys!

Reply With Quote
  #2  
Old 01-20-2010, 07:52 AM
Registered User
 
Join Date: Aug 2005
Location: Cordova,TN
Posts: 140
yes

If its the line from the back of the manifold, YES. It is the line that controls the boost. Banjo fitting should come on line-NO do not use flex line. Part should be available from this source. PM me if you need help, as I too have an 85 300sd.

M
Reply With Quote
  #3  
Old 01-20-2010, 10:18 AM
Registered User
 
Join Date: Jun 2008
Posts: 343
The normal vacuum line is just fine. The only issue is that it is usually only good for 10 years or so. The hard plastic line will last twice as long. But it costs much more and you can't just go to an auto parts store and purchase it.

FWIW you aren't dealing with vacuum here . Your engine is turbocharged.
Reply With Quote
  #4  
Old 01-20-2010, 11:04 AM
Registered User
 
Join Date: Sep 2004
Posts: 8,971
Quote:
Originally Posted by treiberg View Post
With this line broken, doesn't this mean that I virtually had no vacuum?
That line has nothing to do with the vacuum system. It routes manifold pressure to the ALDA for the purpose of fuel management.
Reply With Quote
  #5  
Old 01-20-2010, 12:16 PM
Banned
 
Join Date: May 2002
Location: Blue Point, NY
Posts: 25,396
I would not attempt to replace that line with any hose. It's a pressurized line and it routes to a very unpleasant location.

The proper solution is to obtain the line and banjo fitting as an assembly from Phil on this site. Then, you've got the proper solution that will be durable.
Reply With Quote
  #6  
Old 01-20-2010, 12:26 PM
Registered User
 
Join Date: Jan 2002
Posts: 18,350
When the plastic line broke on my TD I replaced most of it with flexible copper tubing I bought at the hardware store. It's the tubing typically used to hook up icemakers on refrigerators. I thought it would last longer than plastic or rubber. I did this after I discovered that the plastic line kept getting blown off the banjo fitting when climbing long steep grades in the Rocky Mountains in very hot weather. I used a piece of rubber hose to connect the copper to the banjo fitting and put small clamps around it.

Just for the record, even non-turbocharged diesels don't produce vacuum in their intake manifolds since there is no throttle.
__________________
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
  #7  
Old 01-20-2010, 01:42 PM
Registered User
 
Join Date: Sep 2007
Location: Bakersfield
Posts: 216
Thanks guys for the correction regarding vacuum. I realize now that this is not the source for vacuum, that must come from a vacuum pump. I just used some vacuum tubing to connect this last night and it seemed to fit nice and snug, but it sounds like I probably need to get some harder tubing for the best solution.

Just curious, what effect was this broken line having? It seems like it would be a bleed point for the turbo pressure and take away from the performance, possibly substantially. It does seem that the acceleration was pretty poor on this car. Maybe that was it. Any input?
Reply With Quote
  #8  
Old 01-20-2010, 01:43 PM
Banned
 
Join Date: May 2002
Location: Blue Point, NY
Posts: 25,396
Quote:
Originally Posted by treiberg View Post
Just curious, what effect was this broken line having? It seems like it would be a bleed point for the turbo pressure and take away from the performance, possibly substantially. It does seem that the acceleration was pretty poor on this car. Maybe that was it. Any input?
Without that line, the ALDA doesn't get the pressure signal from the manifold to provide more fuel. Without the fuel, you don't get the horsepower.
Reply With Quote
  #9  
Old 01-20-2010, 01:49 PM
Registered User
 
Join Date: Sep 2004
Posts: 8,971
Quote:
Originally Posted by treiberg View Post
It does seem that the acceleration was pretty poor on this car. Maybe that was it. Any input?
There should be a "night and day" improvement in performance when the line is repaired. If there is not, further investigation is in order. Verifying proper operation of the switchover valve would be a good place to start. Along with ensuring the banjo bolt at the manifold is clean.
Reply With Quote
  #10  
Old 01-20-2010, 01:52 PM
Registered User
 
Join Date: Sep 2007
Location: Bakersfield
Posts: 216
Thanks Brian. But the car would still run, right, it would just have pathetic acceleration? (Because it was running before.) If that's true, I will be pretty excited to get the car put back together to check out the improved performance.

By the way, that line was rock hard, and completely inflexible. I thought I could maybe reconnect it - there was no way that old tubing was going to slide over that banjo joint nipple.

I would also think this would be a common repair in these older cars, but my search didn't yield much. Maybe there is some other term that this line goes by that I am missing in my searching. What is it called? Maybe alda line?
Reply With Quote
  #11  
Old 01-20-2010, 01:54 PM
Banned
 
Join Date: May 2002
Location: Blue Point, NY
Posts: 25,396
Quote:
Originally Posted by treiberg View Post
Thanks Brian. But the car would still run, right, it would just have pathetic acceleration? (Because it was running before.) If that's true, I will be pretty excited to get the car put back together to check out the improved performance.

By the way, that line was rock hard, and completely inflexible. I thought I could maybe reconnect it - there was no way that old tubing was going to slide over that banjo joint nipple.
Correct. However, that line goes through an "overboost protection solenoid" that is also prone to clogging. You need to be able to blow through that solenoid to confirm that it's not full of soot.

No, you cannot reconnect the line. Just purchase a new line which comes with the banjo attached. Anything else won't last.

Call Phil and ask him for the pressure line from the manifold to the overboost solenoid. I'm sure he'll get you the correct part.
Reply With Quote
  #12  
Old 01-20-2010, 02:18 PM
tbomachines's Avatar
ಠ_ಠ
 
Join Date: Mar 2009
Location: Philadelphia
Posts: 7,362
Flexible vacuum hose will do for a temporary fix. I had rubber line on mine for a couple months with no problems...just make sure that it isn't touching anything hot. I imagine there is a certain amount of flex with the rubber line as well, so perhaps the overboost solenoid might produce too little fuel compared to a hard line, but better than nothing.

I should have replaced it with the hard plastic line immediately but kind of forgot about it
__________________
TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth
Reply With Quote
  #13  
Old 01-20-2010, 02:20 PM
tbomachines's Avatar
ಠ_ಠ
 
Join Date: Mar 2009
Location: Philadelphia
Posts: 7,362
Quote:
Originally Posted by kerry View Post
When the plastic line broke on my TD I replaced most of it with flexible copper tubing I bought at the hardware store. It's the tubing typically used to hook up icemakers on refrigerators. I thought it would last longer than plastic or rubber. I did this after I discovered that the plastic line kept getting blown off the banjo fitting when climbing long steep grades in the Rocky Mountains in very hot weather. I used a piece of rubber hose to connect the copper to the banjo fitting and put small clamps around it.

Just for the record, even non-turbocharged diesels don't produce vacuum in their intake manifolds since there is no throttle.
That's a good idea...I bet a brake line would work as well, and just as easy to find in the parts store...a flange fitting on the end would make it fit nice and snug with a small hose clamp.
__________________
TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth
Reply With Quote
  #14  
Old 01-20-2010, 04:30 PM
whunter's Avatar
Moderator
 
Join Date: Dec 2003
Location: Metro Detroit, Michigan
Posts: 17,390
Thumbs up Answer

Quote:
Originally Posted by treiberg View Post
Was finishing up a valve adjustment and happened to notice that the plastic line that supplies vaccum from the intake manifold was broken right at the connector that goes into the manifold. OK, better fix this...

The line is a hard, clear plastic line. It is very hard and the portion that is broken still over the nipple will probably need to be cut off to get it off.

Questions:

-Do I need to replace it with this hard line or can I just use the black, flexible vaccum hose? Maybe this stuff used to be flexible, and it hardened over time, but not sure. Since it is transparent-yellowish, I suspect it is different and maybe withstand high temp better or something.

-With this line broken, doesn't this mean that I virtually had no vacuum? Wouldn't this have caused very noticeable issues? Car seemed to be running fine before, so maybe the line got cracked from the work I was doing. What symtoms would a person see with little to no vacuum? Loss of power brakes, tranny problems, etc.

Thanks guys!
FYI: These are PRESSURE lines, NOT vacuum.


LINE...FROM CHANGE OVER VALVE TO INJECTION PUMP GOVERNOR ALDA)...OM617
MB# 6170700681
Fastlane:
http://catalog.peachparts.com/item.wws?sku=6170700681

MB# 6170700781
LINE...FROM INTAKE MAINFOLD (CHARGE AIR) TO CHANGE OVER VALVE...OM617
Fastlane:
http://catalog.peachparts.com/item.wws?sku=6170700781

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 11:56 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2024, 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