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#1
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Heat problem in 1980 300sd
Completely lost my heat, but not the blower. A/C didn't work when I got the car, but that is the compressor as I was told by previous owner (in Canada in September, you don't worry about your A/C for about 10 more months ).
Am I to assume that it is the monovalve, and if so, how do I diagnose it to make sure that is what it is? Thanks, Dunl
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79 300SD - $50 out of pocket purchase 03 Dodge Ram 3500 CTD 2003 VW Jetta TDI |
#2
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Also, where is the best place to source these?
Thanks.
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79 300SD - $50 out of pocket purchase 03 Dodge Ram 3500 CTD 2003 VW Jetta TDI |
#3
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Your model doesn't have a monovalve. You have the dreaded servo unit. I can't help you on that one, maybe someone else with a servo equipped MB diesel can.
-Joe
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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate Sooner or later every car falls apart, ours does it later! -German Narrator in a MB Promotion Film about the then brand new W123. |
#4
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Sounded like $500 to replace that stinkin servo in my car, so I just took two pieces of heater hose and bypassed it. Removed the non-functioning aux coolant pump at that time also. Now I either have no heat, or it cranks hot out the defrost. If I push defrost first then half push in bi-level, I get a mix. Works good enough for me and cost a couple bucks. I made a thread on that a couple years ago with pics, wonder if it is still here....
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Think Alternative Energy! 300CD '80 (now gone but not forgotten...) |
#5
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Sounds like the job I had done on mine. There is a bypass switch underneath the ignition right now, that turns the blower on or off, and I get heat (used to, anyway), out the defrost - all or nothing.
Guess I'll take a better look tomorrow at it, and check it out. Thanks for the tip, and if you find that thread, I'd like to take a look at it. Dunl
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79 300SD - $50 out of pocket purchase 03 Dodge Ram 3500 CTD 2003 VW Jetta TDI |
#6
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The guys who restore 71-73 imperials know a bit about this system, they call it Auto-Temp II.
http://www.duricy.com/~imperialist/tips.html http://www.imperialclub.com/Repair/Air/index.htm George Murphy seems to be the MBZ expert on this, but I don't think he ever set up a web page.
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'79 300SD W116 '86 190E 2.3-16V W201 '92 300D 2.5 W124 '99 E320 4MATIC S210 |
#7
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Quote:
otherwise known as the Evil vacuum servo. Thats your problem...as the 1980 300SD was a W116 chassis and never had a monovalve.
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Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche Last edited by boneheaddoctor; 01-04-2006 at 09:34 AM. |
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Thanks for the tips and pictures, boneheaddoctor. $495 for an aluminum servo would fix the problem, but also my wallet for a while.
I did find your thread Jimmy, thanks for the info.....I bumped it to the top in the hopes that someone will have some pics or other options....you never know what some inventive diesel-head will come up with.
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79 300SD - $50 out of pocket purchase 03 Dodge Ram 3500 CTD 2003 VW Jetta TDI |
#9
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Quote:
Performance products sells a technologicly up to date replacement for that monstrocity......Fastlane carries it... True it costs more but its not going to fail again....
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Proud owner of .... 1971 280SE W108 1979 300SD W116 1983 300D W123 1975 Ironhead Sportster chopper 1987 GMC 3/4 ton 4X4 Diesel 1989 Honda Civic (Heavily modified) --------------------- Section 609 MVAC Certified --------------------- "He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche |
#10
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I agree with BHD (a rare occasion). The Performance high tech upgrade is probably worth it. I did put the aluminum bodied upgrade on my 77 a few years ago before Performance came out with their system. I got mine from another supplier at a discount because it had a crack in an unimportant piece of plastic. Check junkyards, there may be a good one out there. Ebay sometimes has used ones.
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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 |
#11
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I have the 1980 AC Servo unit
I also have the AC servo unit and have had trouble with it for quite a while.
Looking forward to forking over the money for a new one just to get the whole package working like it is supposed to. But... when it got cold I bypassed the unit and ran hot water straight into the cabin (just like the other posts talk about). I seem to remember having to replace the small electric auxillary pump too. A salvage yard had the aux pump for $25, not too bad. I tore apart that AC servo looking to fix anything I could find. Darn confusing. Did have a broken arm that I tried to JB weld. It did not work. Hence the search for a new unit. Anyone ever replaced the AC servo in a 1980 with some other year method ? I have a 1981 donor car, but just can't see what needs to be switched to eliminate the 1980 AC servo unit. |
#12
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Okay, I removed my servo, and now I have heat. But I am guessing that I now have to plug all the vacuum lines going out of the (removed) servo, as the vehicle keeps running when the key is turned off and removed.
While waiting for the glow plugs to heat, I could hear the coolant running and the bubbles gurgling, only when the glow plugs were heating (checked 4 times). I'm guessing this means my auxillary water pump works, and it doesn't need replaced? Plus, I remember hearing something about replacing a fuse with another to extend the life of said aux. water pump - can't find info though. Thanks, Dunl
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79 300SD - $50 out of pocket purchase 03 Dodge Ram 3500 CTD 2003 VW Jetta TDI |
#13
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Anyone able to help here?
Thanks, Dunl
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79 300SD - $50 out of pocket purchase 03 Dodge Ram 3500 CTD 2003 VW Jetta TDI |
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