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 06-11-2005, 12:39 PM
Fuzzball's Avatar
Registered Agitator
 
Join Date: Jan 2004
Location: Central Texas
Posts: 716
'84 300D A/C and Coolant issue

ok...this is not my car, so I can't really give you a lot of information.

When using the AC, after a while there is a coolant leak from the Y pipe mounted on the firewall and feeding the inside of the car.

A/C is not blowing all that cold, but I can't tell if it's cooling at all as it was evening when I was testing.

Here is what I suspect: With a low charge, the AC is freezing up the evaporator core inside. With this freezing up, the coolant is restricted causing back pressure and thus the high pressure leak around the seal.

Anyone think I'm completely nuts, or is this possible.

The problem ONLY occurs when the A/C is used.

The leak is from the bottom side of the Y connector.

Thanks in advance!
__________________
1998 W202 C230 - The money pit of late.
1984 W126 300SD (356,800 miles) Gone to the wrenchapart
1984 W123 300D Gone to the wrenchapart
1972 W108 280SE 3.5 (sold but not forgotten)
1986 Buick Grand National 3.8l Turbo (86k miles)
1966 Glassic Model 'A' Replica http://www.glassicannex.org

http://banners.wunderground.com/weat...Round_Rock.gif
Reply With Quote
  #2  
Old 06-11-2005, 03:29 PM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,277
A 1984 300D.... ?
and there is another thread saying you are picking up a 1984 300D...
very suspicious....

Why do you think the AC is low on charge ?

With a low charge the AC should not even be coming on.
If it is coming on and then stops cooling then it can be the expansion valve failing to keep the evaporator above 32 degrees... if it gets below that then ice forms in the air flow path....making it feel like it is not cooling.

Have you checked that Flap which , if not closed, allows warm air to mix with the cold air, making it feel like the AC is not working ?

That ought to keep you busy a while....

Last edited by leathermang; 06-11-2005 at 03:47 PM.
Reply With Quote
  #3  
Old 06-11-2005, 06:14 PM
Fuzzball's Avatar
Registered Agitator
 
Join Date: Jan 2004
Location: Central Texas
Posts: 716
Ok, here are some pictures.

in the first picture, the Red arrow shows where the coolant is leaking from. It supposedly comes out in a hard stream.

In the second picture, I have circled the "Y" pipe in blue. This Y pipe is connected to the hose coming off the manifold.

In the final picture the Yellow line points to where the water streams out, and the red arrow shows where the hose enters the firewall.

I believe that this may be due to icing up of the underdash parts which is causing the coolant to build up pressure and squirt out passed the hose clamp. I say this because when I had a problem with low coolant level once, I had a freezing problem.

Remember, I claimed ignorance of the way it worked, and I am giving you theories from that viewpoint....

Hope this helps.
Attached Thumbnails
'84 300D A/C and Coolant issue-sharad_pipes_1.jpg   '84 300D A/C and Coolant issue-sharad_pipes_2.jpg   '84 300D A/C and Coolant issue-sharad_pipes_3.jpg  
__________________
1998 W202 C230 - The money pit of late.
1984 W126 300SD (356,800 miles) Gone to the wrenchapart
1984 W123 300D Gone to the wrenchapart
1972 W108 280SE 3.5 (sold but not forgotten)
1986 Buick Grand National 3.8l Turbo (86k miles)
1966 Glassic Model 'A' Replica http://www.glassicannex.org

http://banners.wunderground.com/weat...Round_Rock.gif
Reply With Quote
  #4  
Old 06-11-2005, 07:10 PM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,277
You seem to be connecting engine coolant and AC refrigerant with regards to this.. ????
At what point do you see these interacting ?
Reply With Quote
  #5  
Old 06-11-2005, 07:21 PM
Fuzzball's Avatar
Registered Agitator
 
Join Date: Jan 2004
Location: Central Texas
Posts: 716
I'm figuring they interact inside the car where the blower uses them to blow either hot or cold air....
__________________
1998 W202 C230 - The money pit of late.
1984 W126 300SD (356,800 miles) Gone to the wrenchapart
1984 W123 300D Gone to the wrenchapart
1972 W108 280SE 3.5 (sold but not forgotten)
1986 Buick Grand National 3.8l Turbo (86k miles)
1966 Glassic Model 'A' Replica http://www.glassicannex.org

http://banners.wunderground.com/weat...Round_Rock.gif
Reply With Quote
  #6  
Old 06-11-2005, 07:24 PM
jbaj007's Avatar
Registered User
 
Join Date: Jun 2001
Location: Santa Monica, CA
Posts: 2,053
The evaporator is not nearly close enough to the heater core and hoses to even come close to icing them. Also, when the monovalve is closed the pressure in those lines is as high as it ever gets anyway. The systems are essentially isolated from one another, at least from an energy point of view. (Air flow from flap positions doesn't count. )

When the A/C is on, the monovalve should be closed and that may be why the coolant leaks (pressure). Tighten the hose clamps or/and replace those heater hoses and I think that the leak part of the problem will be solved.

As for the A/C not cooling as well as you'd like; wouldn't hurt to check the monovalve diaphragm while you're there. If that's OK you can check the A/C, subsystem by subsystem; clutch, aux. fan, viscous fan, condensor clean, pressures, PBU, etc.
__________________
The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)
Reply With Quote
  #7  
Old 06-12-2005, 08:22 AM
TonyFromWestOz's Avatar
"The Wizard of Oz"
 
Join Date: Jan 2004
Location: Perth, Western Australia
Posts: 834
If you have coolant leaks, fix the leaks. They are not connected with the A/C.
If your A/C is not cooling, ensure that your heater is off. If you cannot turn the heater off (ACC issues?) check the temperature of the refrigerant from the compressor to the condensor, it should be hot. If so, check the refrigerant coming from the evaporator, it should get COLD.
If not, problems with A/C
__________________
Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.
Reply With Quote
  #8  
Old 06-12-2005, 11:37 AM
whunter's Avatar
Moderator
 
Join Date: Dec 2003
Location: Metro Detroit, Michigan
Posts: 17,350
Lightbulb Physics of climate control and engine cooling 101

Cooling system leaks become more notable during A/C operation because.
#1. Condenser heat transfer to radiator.
#2. Engine load.
#3. Reduced radiator heat rejection capacity = Lime buildup, corrosion or material breakdown from age.
#4. Bad thermostat.
#5. failing water pump.

Added heat = added pressure = weak points fail = a damp spot becomes a stream or spray.

Best advice:
#A. Replace the thermostat.
#B. Flush the cooling system.
#C. Disconnect, clean the leaking hose end and fitting, reconnect.
#D. Clean any trash from between radiator and condenser.
#F. Clean trash from under electric cooling fan, may need to remove fan for this.
__________________
ASE Master Mechanic
asemastermechanic@juno.com

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Prototype Vehicle build.
Prototype Fleet Durability
Prototype vehicle instrumentation.
Technical Quality Auditor.
Automotive Technical Writer

1973 300D
1973 309D - stolen
1978 280SE
1980 240D
1983 300D
1984 190D
Reply With Quote
  #9  
Old 06-12-2005, 11:59 AM
Registered User
 
Join Date: Sep 2001
Location: central Texas
Posts: 17,277
Might be good to look at it backwards.... a leak means that the pressure can cross the threshold from just hot water to steam at a much lower temperature.... due to the lack of pressurization ...
Also need to check the Radiator Cap pressure.
Reply With Quote
  #10  
Old 06-12-2005, 08:11 PM
Palangi's Avatar
L' Résistance
 
Join Date: Dec 2000
Location: Republique de Banana
Posts: 3,496
When I get a "new" old Mercedes one of the first things I do is inspect all the hoses and clamps. I have found bad upper hoses due to rubbing on 2 cars. I have never found a bad heater hose, but I have found numerous hose clamps to be loose and leaking. From the looks of it, those are the original factory hose clamps, which means they probably haven't been tightened in 21 years.
__________________
Palangi

2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg



TRUMP .......... WHITEHOUSE
HILLARY .........JAILHOUSE
BERNIE .......... NUTHOUSE
0BAMA .......... OUTHOUSE
Reply With Quote
  #11  
Old 06-12-2005, 11:30 PM
Fuzzball's Avatar
Registered Agitator
 
Join Date: Jan 2004
Location: Central Texas
Posts: 716
Thanks Everyone, I'll take this information to the owner and let him know.

Of course, now that I have all this input, he'll probably just take it to his indie and get it fixed by him...but I had to try, he asked.
__________________
1998 W202 C230 - The money pit of late.
1984 W126 300SD (356,800 miles) Gone to the wrenchapart
1984 W123 300D Gone to the wrenchapart
1972 W108 280SE 3.5 (sold but not forgotten)
1986 Buick Grand National 3.8l Turbo (86k miles)
1966 Glassic Model 'A' Replica http://www.glassicannex.org

http://banners.wunderground.com/weat...Round_Rock.gif
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


Similar Threads
Thread Thread Starter Forum Replies Last Post
87 300D Coolant issues dlssmith Diesel Discussion 26 02-16-2005 10:05 PM
Drain coolant while changing thermostat on 92 300D 2.5 ? kamil Diesel Discussion 2 12-21-2004 12:42 PM
Coolant leaks and general weirdness. rwthomas1 Diesel Discussion 10 05-30-2003 05:49 PM
W-140--Any way to test the coolant temp sensor for the a/c system oldsouth Tech Help 9 12-26-2002 12:09 PM
Coolant issue: perhaps undue paranoia. cincuenton Tech Help 2 10-14-2002 04:52 PM



All times are GMT -4. The time now is 12:58 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, 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