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 ShopForum > Technical Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 01-21-2016, 09:19 PM
Registered User
 
Join Date: Oct 2014
Posts: 11
What is this leaking coolant? Monovalve?

Short version, friend of mine has a 85 300TD that is her only car (original owner). She has no heat, car doesn't warm up. I said thermostat. She takes it too her mechanic of 30 years and he replaces something and the car overheats 20 minutes into her way home. She claims the temp gauge pegged . Excellent. Mechanic won't answer his phone.

I show up and pick her up, but first I am going figure out what went wrong. My competency with car repair is very high so don't be afraid to use some detail. For whatever reason I haven't found any good info about what this is and what it does.



Last edited by ghetto jet; 01-22-2016 at 12:47 AM.
Reply With Quote
  #2  
Old 01-21-2016, 10:36 PM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 25,791
yes, that is the monovalve, and it's the heater coolant flow valve.
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #3  
Old 01-22-2016, 12:49 AM
Registered User
 
Join Date: Oct 2014
Posts: 11
So it's two different parts or it is one part that has two names? Where would you suggest buying one?
Reply With Quote
  #4  
Old 01-22-2016, 09:21 AM
toomany MBZ's Avatar
Registered User
 
Join Date: Nov 2006
Location: central Va
Posts: 7,820
Yes, mono valve, the red arrows point to it, the blue arrows point to the housing.

Seems there is an issue regarding part #293 or #125. Or perhaps the housing itself has developed a crack.

If that doesn't open, you won't get heat.

Engine overheating is probably a different issue, until the mechanic talks, you don't know what he replaced, receipt?

Good luck.
Attached Thumbnails
What is this leaking coolant?  Monovalve?-screen-shot-2016-01-22-8.20.56-am.jpg  
__________________
83 SD

84 CD
Reply With Quote
  #5  
Old 01-22-2016, 09:31 AM
Registered User
 
Join Date: Jan 2006
Location: Tucson, AZ
Posts: 3,809
And he probably didn't "burp" the system after draining the coolant.
__________________
“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now
Reply With Quote
  #6  
Old 01-22-2016, 09:38 AM
Posting since Jan 2000
 
Join Date: Sep 2011
Posts: 4,846
Yes, and if the vent line from the top radiator tank to the reservoir is blocked off it will be near impossible to burp it.

To the OP, notice what Mike caught. Make sure the hose I described is in place and that the air is bled after your repair.
Reply With Quote
  #7  
Old 01-22-2016, 11:37 AM
vstech's Avatar
DD MOD, HVAC,MCP,Mac,GMAC
 
Join Date: Mar 2006
Location: Mount Holly, NC
Posts: 25,791
Quote:
Originally Posted by ghetto jet View Post
So it's two different parts or it is one part that has two names? Where would you suggest buying one?
you were confused as to what it does, and I was explaining to you it's function.

finding it is another problem...

here on this parts sales site... the solenoid is listed as NLA...
Pelican Parts - European Automotive Parts and Accessories - Porsche • BMW • Mercedes • Volkswagen • Audi • Saab • Volvo • MINI

here's a link for the entire part... $$$

until you find out what is leaking, and why the car is overheating, I'd install a Pex ball valve, and operate it manually...
__________________
John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!
Reply With Quote
  #8  
Old 01-22-2016, 12:09 PM
Registered User
 
Join Date: Dec 2007
Posts: 3,494
Yes, the system needs to be burped. Take the top hose off the radiator and fill with 50/50 coolant/distilled water mix. I start the engine with the heater set to "high". Of course this is after a very thorough flush of the coolant. I've used both the prestone back flush kit (only install using a spare heater hose when you are backflushing, then reinstall the original heater hose because Prestone backflush kits are known to leak during everyday driving) and the famous Mercedes Citric flush (some people have had problems with the citric flush but it seems to go fine for me).

After all that, the car may need a new heater control valve (monovalve) repair kit which is a lot less money than an entire new heater control valve. It is my recommendation to stay away from the MTC brand and go with genuine Mercedes though a bit more $$$$$$, your stress level will remain lower.

http://www.pelicanparts.com/cgi-bin/ksearch/PEL_search_2014.cgi?command=show_part_page&please_wait=N&SUPERCAT_FLAG=Y&make=MBZ&model=3306§ion=ventht&page=1&bookmark=2&part_number=000-835-06-44-MBZ
__________________
1991 560SEL, 1984 300DT
Reply With Quote
  #9  
Old 01-22-2016, 03:48 PM
Registered User
 
Join Date: Aug 2010
Location: Sacramento, CA
Posts: 2,084
W123 ones are quite expensive, though I find these cars in the junkyard often enough now. If my housing failed (OP's appears cracked), I would just run 5/8" heater hose (I use silicone, lasts forever & more flexible) where the monovalve sat, then install a later one from a W124 (cheaper, I have one from ebay) where the aux water pump (electric) sits (front passenger side). The aux pump isn't needed (perhaps in Germany or Alaska) and can even cause a dash fire. One guy here did that. You would need to extend the monovalve wires. For now, do step1 to get thru the winter. That might even keep the babe on your leash. If the relationship progresses, work on a used monovalve. One guy even replaced it w/ a manual on/off valve for winter vs summer mode.
__________________
1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans
Reply With Quote
  #10  
Old 03-02-2016, 06:58 AM
Registered User
 
Join Date: Oct 2014
Posts: 11
Just to update, the mechanic is a retired MB dealer tech with 40 years of experience. He works on a short list of cars for people that he knows. I'm fairly certain he put a used monovalve on the first time, one he had laying around. It was leaking and caused the overheat. He apologized for not test driving the car, fixed it, and dropped it off working fine.

The heat worked properly for about 2 weeks, the coolant temp would get to 80. Then the engine stopped warming up properly and was not producing heat. I drove the car myself, even with the block heater running prior to start up, after 30 minutes of driving the temperature needle was barely above 40. I made a grille block and the needle would get up to 60 and hold while driving, but there was still just cold air coming out of the vents.

The car has been back to the mechanic friend twice with no resolution, it's well over an hour drive each way, quite a trip to make with no heat for a 71 year old woman. Now he is sick and can't look at it again until further notice. My friend is concerned the mechanic might be suffering from the early stages of dementia, though I wonder that about her when she tries to relay what he told about the car and seems to have no idea. The mechanic did not return any of my calls so I'm in the dark.

I was going to try and not get in the middle of this debacle but it is getting a bit ridiculous.

I'm thinking the recent overheating took a toll on the thermostat and it is stuck open. So this is not a monovalve issue now, but the mechanic is still chasing that prior problem. Could be both though.
Reply With Quote
  #11  
Old 03-02-2016, 06:58 AM
Registered User
 
Join Date: Oct 2014
Posts: 11
double post
Reply With Quote
  #12  
Old 03-02-2016, 03:41 PM
Registered User
 
Join Date: Feb 2004
Location: Austin, TX
Posts: 166
Quote:
Originally Posted by ghetto jet View Post
. . . after 30 minutes of driving the temperature needle was barely above 40. I made a grille block and the needle would get up to 60 and hold while driving, but there was still just cold air coming out of the vents. . . .
For whatever it's worth, I experienced the above symptoms when my thermostat failed in the open position.

Were you ever able to ascertain if the mechanic actually replaced the thermostat? Or were his repairs limited to the monovalve?

A thermostat is not very expensive; I'd probably replace that and put new coolant in. Lots of info on this forum on both the proper coolant to use and how to properly "burp" the system after replacing the thermostat and refilling the coolant if you use the "search" feature.
__________________
Christopher
'06 Mercedes E350 station wagon
'85 Mercedes 300D (#2)
'79 Cadillac Sedan deVille

'85 Mercedes 300D (#1) sold back to orig. owner after 5 years on 8-1-06.
'84 Volvo 264GL Diesel, owned 2000-2013

Last edited by Volvo Diesel; 03-02-2016 at 11:12 PM.
Reply With Quote
  #13  
Old 03-07-2016, 02:39 AM
Registered User
 
Join Date: Oct 2014
Posts: 11
Quote:
Originally Posted by Volvo Diesel View Post
For whatever it's worth, I experienced the above symptoms when my thermostat failed in the open position.

Were you ever able to ascertain if the mechanic actually replaced the thermostat? Or were his repairs limited to the monovalve?

A thermostat is not very expensive; I'd probably replace that and put new coolant in. Lots of info on this forum on both the proper coolant to use and how to properly "burp" the system after replacing the thermostat and refilling the coolant if you use the "search" feature.

I do not know, unfortunately. Seems like there is an appointment this week.
Reply With Quote
  #14  
Old 03-19-2016, 12:14 AM
Registered User
 
Join Date: Oct 2014
Posts: 11
Well, I saw the car yesterday after a short trip and noticed antifreeze dripping on the ground. Popped the hood and the monovalve was gone, the two hoses were joined by and clamped to short piece of metal tube. It was leaking at the connection, which seemed to be on tight enough but to an improper intermediate pipe. I don't know what exactly was done but she was charged $375 for this work. Perhaps it was to cover ordering another part. The saga continues. It puts out heat regardless of the dial setting.
Reply With Quote
  #15  
Old 03-19-2016, 11:55 AM
Registered User
 
Join Date: Sep 2006
Location: Middle TN
Posts: 3,236
The car needs a working thermostat and cooling system. The thermostat can be tested prior to replacing. Quality parts will work. Knockoff imports perhaps or not.

The heat system needs a working mono valve to control heat. There are also other components such as the push button unit and vacuum pods.

Deal with the mono valve and cooling system first. Send me a PM if you want a FSM to the 126 cars with similar systems.
__________________
85SD 240K & stopped counting. 84SD 180,000. Thinking of painting both.
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 08:04 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, 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