Mercedes-Benz Forum banner

Status
Not open for further replies.
1 - 7 of 7 Posts

·
Registered
Joined
·
125 Posts
Discussion Starter #1
I have a 1980 300D, and it doesn't turn off by key, and now the stop switch under the hood doesn't work either. I tried popping off the linkage attached to the injector pump and yanking on it, and that didn't work either. Disconnecting the battery doesn't work. The only way I got it to turn off was by disconnecting the fuel supply line at the clear filter, and then accelerating a little to hurry up the shutdown time. But it still took a good 10 minutes to turn off.

My problem is that I'm in desperate need of a vacuum pump rebuild, but it makes me wonder. Why isn't it turning off with the stop switch/linkage? Is that still somehow because of the vacuum pump? I'm going to order a vac pump rebuild kit (thanks to info from someone on this forum), but until then, is there another way to shut off the engine? I don't think applying vacuum to the vacuum unit on the injection pump works either. I'd appreciate any information anyone can provide, no matter how small, etc.
 

·
Registered
1994 SL320, '76 240D
Joined
·
153 Posts
Cover the intake - put your hand over the intake tube to cut off air flow - this is how yo...

Cover the intake - put your hand over the intake tube to cut off air flow - this is how you shut down Gas engineed Remote Controled cars (works on real cars too! - engine needs air to run)
 

·
Registered
Joined
·
125 Posts
Discussion Starter #3
Thanks for the suggestion

Ideally I would imagine that blocking the intake would work (ideally the stop switch would work!), but alas, whenever I put my hand over the intake I would hear a SSSSSSSSSSSSSSS......Air being sucked in from somewhere else around the area. So I couldn't deprive it of air and had to go the fuel line route again.
 

·
Registered
Joined
·
125 Posts
Discussion Starter #4
I think that oil might have gotten into the engine

I think that oil has gotten into the engine by way of the intake (since the line from the vacuum pump to the air cleaner has oil in it). That is why it continues to run even after I push the stop lever. I cut off the fuel, but it is now running on oil.

Does anyone think that I can just disconnect that line from the vacuum pump to the air cleaner until I get my vac pump repair kit? I don't want to cause any damage to the engine because of the oil, but it's currently my only mode of transportation.
 

·
Registered
1994 SL320, '76 240D
Joined
·
153 Posts
Yes, the car is running on blow-by that is routed back to the intake from the crankcase. M...

Yes, the car is running on blow-by that is routed back to the intake from the crankcase. My '76 300D had some nasty blow-by when I first bought it and if you let the car idle with the adjustment knob turned up it would eventually start to rev-up quite high on its own (from blow-by).

Thats a tough situation you have there. Try turning it off when the car is at idle in drive, the revs might be low enought to stall the engine. If not I think you will be fine disconecting the PCV tube from the intake.
 

·
Registered
Joined
·
125 Posts
Discussion Starter #6
What about the oil already inside the engine?

Do you remember about how long after you fixed the blowby problem the engine would continue to run by itself? I disconnected the PCV line yesterday, and have drove the car twice, but I think it's still got some residual oil to run on after I attempt to turn it off. Do you think the oil will just burn up and away eventually?
 

·
Registered
1994 SL320, '76 240D
Joined
·
153 Posts
Yes there could be be some residual oil still in there, but it could also be carbon. It pr...

Yes there could be be some residual oil still in there, but it could also be carbon. It probably is a combonation of both. Try using Diesel purge, Lucas Injector cleaner, STP diesel fuel treatment or Diesel Kleen. That in conjunction with removing the PCV valve should help shut it down.
 
1 - 7 of 7 Posts
Status
Not open for further replies.
Top