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 12-17-2006, 12:45 PM
Registered User
 
Join Date: Nov 2006
Location: Boston, MA
Posts: 106
tried to fix monovalve, broke car instead

okay, okay... thats an exaggeration. but i tried to inspect and r&r my monovalve - the part with the torn diaphragm and all. it turned into a minor disaster. first, all the coolant drained out onto the pavement when i opened it up. two, i couldnt get the valve out of the housing. it was completely stuck in. i tried to be gentle, but eventually the whole outer housing just sort of popped apart. and, more crucially, i broke one of the thin copper wires running to the electrical connector. i can still the the broken lead coming out of the coil, but its not connected to the switch.

it seemed like such a simple process. alas, i am a novice. i sort of pressed it all back together, put it back where it came from, topped off the coolant, and gave her a test drive. heat came on, no more coolant spilled out. but still, i have to go get the thing fixed now. yuck.

where did i go wrong? that thing was really wedged in there.

__________________
1982 300sd, 230,000 miles, svo/wvo conversion... yellow

http://www.jaymoschella.com

Last edited by its_snowing; 12-17-2006 at 12:57 PM.
Reply With Quote
  #2  
Old 12-17-2006, 01:12 PM
carnut's Avatar
Registered User
 
Join Date: Jul 2006
Location: Stockton California
Posts: 637
I just replaced my MONO valve insert yesterday and yes it seemed hard to pull up. I got the feeling it was magnetized? Someone more familiar with this valve could hopefully verify this. I know the coil produces a magnetized field to raise and lower the diaphram but I would think this would not be the case with the key off. I've seen alot of these units very rusty upon disassembly in wrecking yards. That would cause stubborn removal as well. Its best to remove this insert with a cold engine and the radiator cap off, no pressure. Less coolant loss.
__________________
81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.
Reply With Quote
  #3  
Old 12-17-2006, 01:20 PM
Registered User
 
Join Date: Nov 2006
Location: Boston, MA
Posts: 106
yeah. my engine was totally cold, and i took the cap off. but still, the cooland poured out in about two seconds. on the other hand, it drained out into an area that was showing a leak sometime ago, so this at least suggests where the leak was coming from.

i put it all back together, and will fix it up tomorrow. im just wondering if i can drive it as is for now.
__________________
1982 300sd, 230,000 miles, svo/wvo conversion... yellow

http://www.jaymoschella.com
Reply With Quote
  #4  
Old 12-17-2006, 01:30 PM
carnut's Avatar
Registered User
 
Join Date: Jul 2006
Location: Stockton California
Posts: 637
Assuming you are not loosing coolant , drive it!
__________________
81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.
Reply With Quote
  #5  
Old 12-17-2006, 01:34 PM
Registered User
 
Join Date: Nov 2006
Location: Boston, MA
Posts: 106
yeah. the valve is in the open position, so i should just have heat, no?
__________________
1982 300sd, 230,000 miles, svo/wvo conversion... yellow

http://www.jaymoschella.com
Reply With Quote
  #6  
Old 12-17-2006, 02:25 PM
toomany MBZ's Avatar
Registered User
 
Join Date: Nov 2006
Location: central Va
Posts: 7,820
I think so.
__________________
83 SD

84 CD
Reply With Quote
  #7  
Old 12-17-2006, 11:52 PM
olsaltybastard's Avatar
Registered User
 
Join Date: Apr 2006
Posts: 147
I recently changed my monovalve insert and am proud to announce that I no longer want to crash my car into a wall!! (long story). I removed the radiator overflow cap and reinstalled it prior to touching the monovalve. Try this next time as it may actually purge the remaining pressure from your cooling system and prevent anti-freeze from spilling on your driveway.
Reply With Quote
  #8  
Old 12-18-2006, 01:03 AM
Banned
 
Join Date: Dec 2005
Location: CA... No. of S.F.
Posts: 890
What's a "monovalve"...??

Quote:
Originally Posted by olsaltybastard View Post
I recently changed my monovalve insert and am proud to announce that I no longer want to crash my car into a wall!! (long story). I removed the radiator overflow cap and reinstalled it prior to touching the monovalve. Try this next time as it may actually purge the remaining pressure from your cooling system and prevent anti-freeze from spilling on your driveway.
What in the world are you guys callin a "monovalve" that has to do with the cooling system... a thermostat???
Anxiously waiting to see if my brain has ceased to work,
Reply With Quote
  #9  
Old 12-18-2006, 01:11 AM
dkveuro's Avatar
Sword of Damocles
 
Join Date: Jun 2003
Location: Here an' there.
Posts: 2,548
Quote:
Originally Posted by Samuel M. Ross View Post
What in the world are you guys callin a "monovalve" that has to do with the cooling system... a thermostat???
Anxiously waiting to see if my brain has ceased to work,
It's a single plunger, heater core coolant whatsit, flow control valve doohickey, that works on a duty cycle doodah on the firewall by the battery thingamyjig.


.
__________________
[http://languageandgrammar.com/2008/01/14/youve-got-problems-not-issues/ ]

"A liberal is someone who feels they owe a great debt to their fellow man, which debt he proposes to pay off with your money."
Reply With Quote
  #10  
Old 12-18-2006, 01:19 AM
ForcedInduction
Guest
 
Posts: n/a
Quote:
Originally Posted by its_snowing View Post
first, all the coolant drained out onto the pavement when i opened it up.
I'm guessing you didn't take off the coolant tank cap first....

Last edited by ForcedInduction; 12-18-2006 at 01:54 AM.
Reply With Quote
  #11  
Old 12-18-2006, 01:29 AM
Registered User
 
Join Date: Aug 2002
Location: NE Okla
Posts: 1,104
The Monovalve is not part of a 1980 or earlier cabin heating system. On those 123's & 126's the 'Dreaded Servo' takes care of this function when it is working.

At any rate the monovalve operates in an on-off cycle related to the heat required and regulates the hot water flow to the heater coil in the cabin. It is not a variable opening valve, just has two positions.
__________________
1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150
Reply With Quote
  #12  
Old 12-18-2006, 01:57 AM
RichC's Avatar
Internal Error 404
 
Join Date: Dec 2005
Posts: 963
Hey, I have a spare monovalve if anyone wants it.

.
Hello All.

I picked up a spare monovalve at the pick n pull the last time I went.

If anyone needs one, I am willing to sell it.

Just PM me here.

Thanks
RichC
__________________

When the power of love overcomes the love of power the world will know peace.
Jimi Hendrix
Reply With Quote
  #13  
Old 12-18-2006, 09:26 AM
Banned
 
Join Date: Dec 2005
Location: CA... No. of S.F.
Posts: 890
Thanks for the education...

Quote:
Originally Posted by Lycoming-8 View Post
The Monovalve is not part of a 1980 or earlier cabin heating system. On those 123's & 126's the ' Dreaded Servo ' takes care of this function when it is working.
At any rate the monovalve operates in an on-off cycle related to the heat required and regulates the hot water flow to the heater coil in the cabin. It is not a variable opening valve, just has two positions.
Thanks for the information... so it's part of the dreaded " Environmental " system on these vintage MBz(s). Lucklily our 1980 240D is strictly a manual system [thank you Lord]... and when we tackle restoration of the 1980 300D's Heat/A-C system I'm hoping to find salvage parts from a 240D that will enable me to convert it to a manual system.

Do any of you guys have any thoughts on the pacticality of such a conversion? I don't think I would have to change any of the console "box"... just the control parts... and of course some to much of what's behind there. Does anyone know of some good system diagrams of these 1980 manual and automatic systems?
Regards,
Reply With Quote
  #14  
Old 12-18-2006, 09:55 AM
Registered User
 
Join Date: Nov 2006
Location: Boston, MA
Posts: 106
actually, i did take the radiator cap off first, which is the strange thing. however, i had been having temp problems that i thought might have been related to a bubble in teh system somewhere. perhaps this had something to do with the fact. also, my coolant system had been staying under pressure endlessly, even when sitting for a while. i really didnt expect to have such a leaky situation at all, and wasnt prepared for it.
__________________
1982 300sd, 230,000 miles, svo/wvo conversion... yellow

http://www.jaymoschella.com
Reply With Quote
  #15  
Old 12-18-2006, 09:55 AM
Registered User
 
Join Date: Jan 2002
Posts: 18,350
Current opinion seems to lean towards repairing with an aluminum bodied servo or the new digital replacement system. Easier than a complete swap of a manual system.

__________________
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
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 10:07 AM.


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