Parts Catalog Accessories Catalog Tech Info Tech Forums
 
  Search our site:    
 Cart  | Project List | Order Status | Help    


  Join us November 1st for Casino Night at the Pelican Parts Open House!
Benefiting LuMind - Research and Treatment for individuals with Down Syndrome
Go Back   PeachParts Mercedes ShopForum > Technical Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 05-23-2011, 10:17 AM
Registered User
 
Join Date: Nov 2004
Location: Dallas, TX
Posts: 4,750
W126 1991 560SEL A/C leak

On my 1991 560SEL, I have a very frustrating leak in the a/c system. The car would hold pressure to 75psi on the high side. The rest gets leaked out. I replaced the condenser, low side hose and compressor.

I pulled a vac and it held, then I charged the system and used my sniffer to check for leaks. Nothing showed up at the condenser, lines or compressor, so I stuck it through the vents and up by the gas pedal where the expansion valve is supposed to be. Still no leak detected.

I've recently replaced the compressor and the condenser on this car in an effort to cure this problem.

Any thoughts as to where this leak could be would be gratefully appreciated. It's going to get hot in Texas over the next couple of months.
__________________
With best regards

Al

Check out the W114, W115 enthusiast website.
http://www.stroke8.org

http://www.w108.org

Join the Mercedes W108 group
http://autos.groups.yahoo.com/group/mercedesw108/

My 280SL restoration

Reply With Quote
  #2  
Old 05-23-2011, 05:23 PM
Registered User
 
Join Date: Feb 2007
Location: los angeles
Posts: 291
Check the evaporator behind dash, put dye in it then check ac drains under car to see if dye traces are present , its very common for evaporator to leak.
Reply With Quote
  #3  
Old 05-24-2011, 11:44 PM
Registered User
 
Join Date: Oct 2004
Posts: 1,507
What are your pressures when the system is full? With this scenario I'd be suspicious that the fans aren't up to snuff causing high side pressure spikes. In which case it would only leak during pressure spikes and be very hard to detect. Flourescent dye is essential for finding difficult leaks.
__________________
90 300TE 4-Matic 280k mi

Turbo Prepped OM103 4-Matic Longblock, 3 dregree cam advance
.42/.48 T3 Turbo 11-18 PSI, Air to Water Intercooler, 40 LB/HR Injectors
Megasquirt MS II Extra, 60-2 Direct Coil Control with Kompressor Flywheel
Full 3" Exhaust, 1 Catalyst, 2X Magnaflow, AEM Wideband O2
Underdrive Alt. and P/S Pulleys, with Auto Tensioner
Lightweight CLK wheels, Vented Rear Brake Discs, .034 Brake Booster.
3.07 Front and Rear Diff, 1st Gear Start
Reply With Quote
  #4  
Old 05-24-2011, 11:50 PM
Registered User
 
Join Date: Nov 2004
Location: Dallas, TX
Posts: 4,750
Thanks for responding, I only measure the pressure when I charge the system and at that point I charge to no more then 225psi on the high side. I will check the fans.
__________________
With best regards

Al

Check out the W114, W115 enthusiast website.
http://www.stroke8.org

http://www.w108.org

Join the Mercedes W108 group
http://autos.groups.yahoo.com/group/mercedesw108/

My 280SL restoration

Reply With Quote
  #5  
Old 05-25-2011, 02:28 AM
Hit Man X's Avatar
I LOVE BRUNETTES
 
Join Date: Sep 2004
Location: FUNKYTOWN
Posts: 8,418
Thumbs up

Did you reseal the expansion valve? It is a BIG PITA so most cars never have it done. My SDL slowly leaks from there and my 300SEL used to also.
__________________
I'm not a doctor, but I'll have a look.

'85 300SD
'87 300SDL
'90 300SEL
'91 560SEL

Eight others from IH, BMW, GM, Ford, and Volvo.

Liberty will not descend to a people; a people must raise themselves to liberty.
[/IMG]
Reply With Quote
  #6  
Old 05-25-2011, 11:14 AM
Registered User
 
Join Date: Nov 2004
Location: Dallas, TX
Posts: 4,750
Eric,

I haven't touched the expansion valve, my buddy David Poole seems to think it would be there and the sniffer may not pick it up because it's covered with some sort of insulation.

It looks like a job for trained limbo dancers.
__________________
With best regards

Al

Check out the W114, W115 enthusiast website.
http://www.stroke8.org

http://www.w108.org

Join the Mercedes W108 group
http://autos.groups.yahoo.com/group/mercedesw108/

My 280SL restoration

Reply With Quote
  #7  
Old 05-25-2011, 11:59 AM
Home appliance genius
 
Join Date: Jul 2009
Location: cleveland
Posts: 943
Quote:
Originally Posted by alabbasi View Post
Eric,

I haven't touched the expansion valve, my buddy David Poole seems to think it would be there and the sniffer may not pick it up because it's covered with some sort of insulation.

It looks like a job for trained limbo dancers.
You can peel away the rubber stuff and put your sniffer to it.

It was the biggest pita job I ever did.
__________________
Eugene

12 Ford fiesta 28k
89 Ford country squire woody wagon 65k
93 300te 4matic 125k
07 BMW X3. 87k
08 mitsubishi fuso 16' box truck 78k
Reply With Quote
  #8  
Old 05-25-2011, 04:49 PM
Registered User
 
Join Date: May 2006
Location: Birmingham, Michigan
Posts: 58
I recently discovered one of the nuts on the line from the receiver to the condensor was bad. It literally broke in half when I touched it so it was obviously the source of my leak. This is the line that's right next to the air intake to the right of the radiator.

I didn't notice this until I was swapping out my US headlights for Euros. It's in a hard to see spot otherwise.

Worth a look. I too was stumped about my AC until I saw this.
Reply With Quote
  #9  
Old 05-25-2011, 10:21 PM
Hit Man X's Avatar
I LOVE BRUNETTES
 
Join Date: Sep 2004
Location: FUNKYTOWN
Posts: 8,418
Thumbs up

The late 126s are a REAL bear due to that extra crash bar/dash support RIGHT in the way. I mean, RIGHT in the way. I just do not trust 20 year old o-rings.

The dealer even diagnosed my 300SEL as 'bad evap core' to the PO before I purchased it... all that was the matter were bad o-rings.

I would agree with David. I have a slow leak on my low side schrader valve so I am going to visit him pretty soon. I do not have time to hunt down a recovery machine plus it is summer so everyone is going to want $$$$$$$ for them. Not to mention it is silly wasting R12.
__________________
I'm not a doctor, but I'll have a look.

'85 300SD
'87 300SDL
'90 300SEL
'91 560SEL

Eight others from IH, BMW, GM, Ford, and Volvo.

Liberty will not descend to a people; a people must raise themselves to liberty.
[/IMG]
Reply With Quote
  #10  
Old 05-28-2011, 11:36 AM
Registered User
 
Join Date: May 2002
Location: Washington, D.C.
Posts: 386
On my 560 it was the expansion valve...

I did a writeup on replacing the valve. You can find it at this link:

http://www.funnyyouasked.com/Mercedes/W126/ExpValve/removal_and_replacement_of_expan.htm

The part is not very expensive. It is imporant that you know how to empty and refill the system, which (by your post) I suspect you know. Figure about an afternoon.

Good luck!
__________________
Henry Bofinger
1989 560 SEL (black/black)
2001 Audi TT Roadster (silver/grey)
Reply With Quote
Old 05-28-2011, 11:36 AM
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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 10:10 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page