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 > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 06-07-2008, 12:43 PM
Registered User
 
Join Date: Aug 2004
Posts: 20
Replacing Evaporator on a 420SEL

My '87 420SEL A/C (R12 system) stopped working due to a low charge and the trouble was traced to a leaking evaporator. The question I have is: How difficult is it to replace the evaporator and is this a DIY project? Are there any resources with pictures showing how it's done? Thank you. T.C.

Reply With Quote
  #2  
Old 06-07-2008, 01:43 PM
Banned
 
Join Date: Apr 2008
Location: Maryland
Posts: 62
very hard, dont bother, either drive it off a cliff or drive w/o A/C
Reply With Quote
  #3  
Old 06-07-2008, 01:52 PM
Registered User
 
Join Date: Dec 2007
Location: Iowa
Posts: 119
I put some Dura-Cool stop leak in my older 96 S600 and it was still holding fine 2 yrs later.. about 20.00 but well worth it..
Reply With Quote
  #4  
Old 06-07-2008, 03:46 PM
Banned
 
Join Date: Apr 2008
Location: Maryland
Posts: 62
Quote:
Originally Posted by platt-deutsch View Post
I put some Dura-Cool stop leak in my older 96 S600 and it was still holding fine 2 yrs later.. about 20.00 but well worth it..

oh now you telling us that? i sold mine '94 E420 cause of it, for $3k that was it
Reply With Quote
  #5  
Old 06-07-2008, 06:20 PM
E150GT's Avatar
I'm a chicken
 
Join Date: Sep 2006
Location: SAN ANTONIO, TEXAS
Posts: 1,148
wow. are you sure its a leaky evaporator? My mechanic told me it is very rare that
an evaporator leaks on a w126. I seriously thought it was my evaporator leaking inside my car, but it turned out to be my expansion valve.
__________________
1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual
Reply With Quote
  #6  
Old 06-07-2008, 08:01 PM
Hit Man X's Avatar
I LOVE BRUNETTES
 
Join Date: Sep 2004
Location: FUNKYTOWN
Posts: 9,087
Thumbs up

Quote:
Originally Posted by benzman666 View Post
very hard, dont bother, either drive it off a cliff or drive w/o A/C


Great advice



There's a write up in the Diesel section from R.Leo, he did the one in his old SDL. Not hard, just very time consuming.

Be 100% sure it's the evap core to be bad, as stated it's very rare for the 126s to have this issue. It's more of an early 140/late 124 deal.
__________________
I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.
[/IMG]
Reply With Quote
  #7  
Old 06-08-2008, 03:10 PM
Registered User
 
Join Date: Aug 2004
Posts: 20
Replacing Evaporator on a 420SEL

I used an electronic leak detector inside the car. About 5 inches from the front of center vent the indicator would go off consistently. You mentioned that it could be the expansion valve. On other cars I've worked on, the expansion valve is fitted to the evaporator unit. If this is the case, wouldn't it be just as hard to get to the expansion valve as the evaporator or are you saying that the expansion valve in a more accessible area? Also, I've heard that this is one of the weak points in these cars. IIRC, Mercedes changed from a copper evaporator design and went to an all aluminium unit in the mid 80's. Any acid that formed in the system would eat away at the aluminum and cause pinhole leaks in the evaporator.

Last edited by Inthemedia; 06-08-2008 at 03:19 PM.
Reply With Quote
  #8  
Old 06-08-2008, 03:17 PM
JimFreeh's Avatar
Benz addict
 
Join Date: Mar 2007
Location: Hampton Roads, Virginia
Posts: 3,366
I had to replace the evap on my 90 560SEL.

Get thee a sniffer and see where the freon is leaking from. For my car, it was alarming whenever I held it in front of the vents.

The expansion valve is under the dash on the left hand side outside of the HVAC plenum, so a leak at the EXP valve will not show up at the vents. You can exchange the exp valve without dissassembly of the HVAC unit.

It's a tedious job, but no harder than the W124 evap I had to exchange on my wife's 95 E320 wagon....

Jim
__________________
14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles
Reply With Quote
  #9  
Old 06-08-2008, 04:00 PM
Hit Man X's Avatar
I LOVE BRUNETTES
 
Join Date: Sep 2004
Location: FUNKYTOWN
Posts: 9,087
Thumbs up

Quote:
Originally Posted by Inthemedia View Post
I used an electronic leak detector inside the car. About 5 inches from the front of center vent the indicator would go off consistently. You mentioned that it could be the expansion valve. On other cars I've worked on, the expansion valve is fitted to the evaporator unit. If this is the case, wouldn't it be just as hard to get to the expansion valve as the evaporator or are you saying that the expansion valve in a more accessible area? Also, I've heard that this is one of the weak points in these cars. IIRC, Mercedes changed from a copper evaporator design and went to an all aluminium unit in the mid 80's. Any acid that formed in the system would eat away at the aluminum and cause pinhole leaks in the evaporator.


Exp valve is on driver side, above accelerator pedal. Not hard to swap out, just a PITA
__________________
I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.
[/IMG]
Reply With Quote
  #10  
Old 06-09-2008, 12:43 AM
E150GT's Avatar
I'm a chicken
 
Join Date: Sep 2006
Location: SAN ANTONIO, TEXAS
Posts: 1,148
Quote:
Originally Posted by Hit Man X View Post
Exp valve is on driver side, above accelerator pedal. Not hard to swap out, just a PITA
very much so. i had to get line wrench crows feet to do it after trying for three days. I had dye in my system so it was very easy just to look and see it was leaking at the expansion valve. perhaps its possible to sniff the condensation on the ground to see if it comes out positive for refrigerant. it would be worth while to remover the bolster under the steering wheel and check the expansion valve, as it got dye all over the carpet and surrounding area. it seems unlikely that the sniffer would detect refrigerant at the vents if it was only the expansion valve, but stranger things have happened, and as expensive and involved replacing a evaporator is i would check everything before i dove in to that.

__________________
1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual
Reply With Quote
Reply

Bookmarks


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 03:35 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2025, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2024 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page