I have an 87 300TD diesel wagon that runs on after the ignition is shut off. I presume that this is a vacuum problem, but I don't know how to pinpoint the problem. By the way, the heat and air conditioning vents on the floor, either side of the console don't work. I don't think the two problems are related. When the climate control comes on, there is a series of clicks that sounds like they are coming from the glove compartment.These vents have not worked for several years. My first priority is the engine shut-off. Is it most likely a vacuum pump or a vacuum line or what. I would like to fix it myself economically, if possible. Thanks in advance for any help. John

You have to check in two places. You have to see if vacuum is getting to and from the switch and then to the shut off element. The lines are brown and are in the engine compartment. You will need to take to a tech if the element is faulty.

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Benzmac:
Donnie Drummonds
1992 500E (very soon I hope :)
1981 280GE SWB
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

John, Try removing the line from the vacuum pump and see if you have it there. If you do then continue to pursue the source of leak as mentioned in the last post. If the vacuum is gone then the vacuum pump is out. before buying a new one, take the old one out and see of the ball bearing assembly is intact. The one on mine had dropped all the ball bearings and cut into the bearing housing. So a rebuild kit in that case is out of the question. If the bearings are ok then you're probably safe to go for the rebuild kit. Best regards, Leon

Will the engine shut off when the doors are locked?

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Robby Ackerman
Past President
Virginia Section MBCA

The A/C vacuum is off the same source so it could be related. As Donnie mentioned the "shut-off" system uses brown lines. See if you have vacuum at the source and then at the servo (on the inj pump), when the key is turned off.

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Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

[This message has been edited by stevebfl (edited 06-17-2000).]

Thanks for the quick replies.
My current situation is as follows:
1. Engine shut-off is not affected by the door locks. The shut-off is delayed with or without the doors locked.
2. When the engine is hot, I have to use the red shut off switch.With a cold engine, shut off is just delayed a few seconds.
3. Not being a mechanic, I don't know what is what and where things are located. If I disconnect the breown line from the unit on the left side of the block, the engine will not shut off at all without using the shut-off button. I also don't which is the servo or the injection pump or the vacuum pump. What is behind the right headlight assembly where several vacuum lines run? One of the lines has what looks like an inline filter.

Please excuse my lack of knowledge, but once I know what is what I can communicate more effectively.

Thanks again for the help!

PS How do you tell if you have vacuum at the source when the key is turned off. That is, while it is dieseling?

If this “failure to shut down” problem happened on a newer Diesel (99 E-300TD) how would one shut it down? I don’t see any switches or buttons under the hood. On a related point, is there a hand powered fuel pump on the newer Diesels?


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1999 E-300TD