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#1
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Non Door Vacuum Leak?
My newly resurrected 81 300TD has a pretty good vacuum leak. I before it attempted suicide by throwing its timing chain, It developed a vacuum leak. The door locks all move in unison, and so I think it is on the transmission side. The the pump was just rebuilt and it will hold vacuum for while.
Where do I start tracing? I just spent an hour searching and reading vacuum posts but didn't find my answer yet. Thanks. |
#2
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Much more likely to be in the climate control. Disconnect the green line leaving the engine compartment and see if the problem goes away.
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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 |
#3
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A large vacuum leak can also be caused by the brake booster. If you don't have one, buy a vacuum tester (Mityvac), as it will be your best friend.
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All Diesel Fleet 1985 R107 300SLD TURBODIESEL 2005 E320 CDI (daily) LOTS of parts for sale! EGR block kit http://www.peachparts.com/shopforum/diesel-discussion/355250-sale-egr-delete-block-off-plate-kit.html 1985 CA emissions 617 owners- You Need This! Sanden style A/C Compressor Mounting Kit for your 616/ 617 For Sale + Install Inst. Sanden Instalation Guide (post 11): http://www.peachparts.com/shopforum/diesel-discussion/367883-sanden-retrofit-installation-guide.html |
#4
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Year?
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Current fleet 2006 E320 CDI 1992 300D - 5speed manual swapped former members 1984 300D "Blues Mobile" 1978 300CD "El Toro" |
#5
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81
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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 |
#6
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I am in the middle of tracing a vacuum leak on my '83 #00 CD, and I first segregated the engine side of the firewall from the cabin side by disconnecting the yellow line to passenger door, fuel door and trunk. I plugged the Climate Control line, and then the nighty vac to test each of these lines. This demonstrated that the leak was in the cabin. I checked all of the line in the engine compartment and they all held vacuum as specified. I am now in the cabin testing each lock line and tomorrow will check the vacuum tank in the trunk.
if needed I can write up my process of elimination and post it tomorrow. |
#7
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there were three HP ratings on the OM616... 1) Not much power 2) Even less power 3) Not nearly enough power!! 240D w/auto Anyone that thinks a 240D is slow drives too fast. 80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works |
#8
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I would appreciate that!
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Mike 1980 300SD 1981 300TD 1998 E320 Gasser Wagon 2000 SL500 |
#9
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Basically.. You're gonna want to use golf tees to block off and isolate parts of the system untill you find the leak. Gonna have to have a hand pump vacuum pump with gauge like a mityvac so you can suck it down and monitor the vac pressure.
Just go through system at a time and check for leaks. Locks Engine shut off Climate control Tranny Vacuum resivoirs.. Will take longer to "pump down" but will hold vac all the same. And... What else? I'm not familiar with all the systems of an '81 TD.
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Current fleet 2006 E320 CDI 1992 300D - 5speed manual swapped former members 1984 300D "Blues Mobile" 1978 300CD "El Toro" |
#10
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So, vacuum for how long?
OK, so I'm reading this thread and I remember what I was wondering when I went through my car testing for vacuum leaks.
How long do these different components need to hold vacuum? Some door locks would hold 15psi (or is it -15 psi?) for longer than others. Is 15 (or -15psi) where I should pump the component down to? How long should the component hold vacuum steady? Is a 1 lb loss per 2 secs OK? What loss rate is or isn't OK? For that matter do the non-driver doors even have to hold vacuum for any significant time at all? Don't they just react to the application of vacuum on one side or the other (lock/unlock)? In fact, isn't some loss even required? If I held -15psi constant on the lock line and then applied -15psi on the unlock side is the unlock side supposed to overcome the still present -15psi of the lock side? Or is it assumed that once the vacuum has been applied on one side that it is slowly lost so that vacuum applied to the other side can function?
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Mike Frederick 1986 300SDL, 240K+ miles 1985 300D KaliKar, 270K+ miles |
#11
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Should hold vacuum forever (theoretically).
Start testing the vacuum "circuits" by testing the pump. Pull everything from the main line including the brake booster. Run the engine and meassure the vac on the main line alone (with the other holes plugged of corse). Add the brake booster. Should still hold steady vac. A leak at the booster would be a major leak and would probably stop everything from working. -15 psi I think I a bit low but whatever it is that you read there at the mainline is all your pump can do. Can't remember the actual spec. but it is around -20 psi I think. After that you'll just go from circuit to circuit like I said before. Locks for example... Pump it down to -20, turn the key to lock and everything should lock. The vac pressure will decrease as all of the actuators do work and you may need to give it a few more pumps to get everything locked but after it locks then it should hold vac again and be ready to unlock if you turn the key to unlock. The three way valve In the drivers door controls wheather the other door locks receive lock or unlock suction. If the locking circuit is not holding pressure then you'll have to to some real work to find the leak. Removing door panels, tracing the vac lines under carpets, isolating each actuator untill you Fing the leaky culprit. Refer to a vacuum diagram of your specific year/model for more complete info. Some have vacuum circuits that others do not but all 123s have Door locks Vac engine shut off Vac resivoirs Climate control I hope this adds to the general knowledge on the subject.
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Current fleet 2006 E320 CDI 1992 300D - 5speed manual swapped former members 1984 300D "Blues Mobile" 1978 300CD "El Toro" |
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