My brother in law has a 1985 300D that keeps running. I said the fuel pump must be getting power but he said it doesn't have an electric pump. He said there is a 'button to push' under the hood to stop the engine and that works but there must be a proper fix.
Any help??
TIA, Dave
You probably have a vacuum leak. When the switch is turned off vacuum is applied to a valve on the injection pump which turns off the fuel supply.
Do your vacuum door locks work, etc?
Yes there is a proper fix. The engine's shut down is accomplished by a "shut down device" a small vacuum powered bellows inside the aft end of the injection pump - a vacuum line is (or should be) attached to it. After twenty years the bellows is worn out and the device needs to be replaced; thats about an $80 part plus 3/4 hour labor.
The shut down device's bellows simply pulls the fuel rack inside the IP to its "OFF" position and the engine stops for lack of fuel.
Meanwhile, there's a STOP lever on the throttle linkage that will stop the engine when its pressed.
Yep, it's a vacuum leak, or a bad fuel cutoff bellows - if you buy, or have access to a small hand pump vacuum tool, (a VERY handy tool if you are priviledged to own one of these cars) you can sort it out fairly quickly. Turning the ignition key off on these cars does two things. It sets the electrical part of the car to the shutdown configuration (power to the clock, interior lights, cig lighter?, and not a lot else) BUT, the ignition switch also has two vacuum lines running to it, which (ideally) control the fuel shutoff at the injection pump.
These car's engines and fuel systems are purely mechanical - electricity is needed to A) heat up the glow-plugs on startup and B) spin the starter. After the engine is started, you can remove the battery, shoot holes in the alternator, etc. These cars also use vacuum for a lot of things, which is weird, because diesels really have no true "manifold vacuum", unlike gas engines - they have to rely on a dedicated vacuum pump. Vacuum is used in the door locks, climate control, cruise control, brake boosting (duh), shift modulation, and, oh yeah, engine cutoff. Fortunately they abstained from vacuum windshield wipers - anyone here old enough to remember those jewels (hint - decelerate to make the wipers go faster)?
I've always thought these cars were ideal for UFO encounters - "OK, green alien scum, you shut down my Becker, but I can still drive over you!" Also handy against the new microwave EMP guns being tested for law enforcement usage - "OK, LAPD scum, you shut down my Becker, but ..."
Conrad
Conrad, you are one funny man. I laughed my ass off ...
Conrad, One thing that will be interesting may be a MB diesel going down the road at
100MPH, cruse control set, and the drivers brain short circuited by the microwave. That could be painful to a lot of people in the way.paul
Hmmm -
When I set my cruise in my 81 300D to 100mph, it just giggles at me. "You want me to do WHAT?". Plus, fortunately, I short-circuited my brain back in the '70s, so that's not an issue.
Conrad
Since you are now assless, mind swapping your heated seats for my plain ones?
Conrad
Wait a minute ........ DO I HAVE HEATED SEATS ON MY 84 399SD !? How to I turn them on?
LOL
Thanks all! I think he is well on his way to a repair.
Dave
Superj wrote:
Urrgh - I'm not sure, since my manuals don't include the very rare
399SD - I've got to find one of these - 4 liters of diesel goodness, oh my ;-)Cheers,
Conrad
oh yeah .... I can't believe you guys have never heard of my 1984 399SD ....
Mia J.
Hmmm.
Things that make you go WTF? OK, either somebody's really good with photoshop or gimp, or I sense that a couple of
190 badges got scavenged - what's the deal, mi amore?Cheers,
Conrad
Photoshop. I'm pretty good. Thanks.
:)
Mia
I purchased a 1985 300D on 5-23-05 and ahve a question about the door locks. They seem very slow and after locking & unlocking them, they won't lock back. I this normal?
I purchased a 1985 300D on 5-23-05 and ahve a question about the door locks. They seem very slow and after locking & unlocking them, they won't lock back. I this normal?
"Cassan" schrieb im Newsbeitrag news: snipped-for-privacy@localhost.talkaboutautos.com...
If you have a W123 it is normal that you can only open and lock the door a few times when the engine is not running. The W123 does not have a separate vacuum pump which is electrical driven as in the newer models . There is only a little reservoir. When you have the engine running, the locks should work fine.
Manfred
Manfred, thanks for the info. The door locks do work fine while the engine is running.
Cassan
Great job Mia. I use Photoshop a lot and that was a good job. Now if I could only get my 240D to act like a 440D!
Okay, but can you open and close them at least four or five times after the engine has shut off? If not you have a leak somewhere. Also, you should be able to unlock all the doors with a twist of the key in the driver's door the next morning. My '81 240D lets me open and close the locks at least three or four times the next morning. My wife's 300D only lets me do it once, or at the most, twice the next day. I suspect a leak in one of the door lock actuators or one of the check valves is bad. When they stop working completely I'll probably start looking.......
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