It's a runaway runaway diesel thread.....a a aaaaHHH..

The ONLY way to surely stop a runaway is starve air intake. As in, slam it shut.

This is why in the open pit mines around here, at the gate there is a vehicle checkstop and if you are driving a diesel the guard will demand you demonstrate the shut off, in fact, he asks where the button is and hits it. The engine has to stop NOW. He opens the hood and looks for the slam gate and that it is closed .... then you can reset it and continue on with a day pass sticker on your windshield.

Here's how I'd do it on my 87 300D: turn the air meter box around so the flow is backwards, and pin the flap open for normal operation. Pull the pin, and slam! The spring shuts the gate and air intake vacuum will pull it shut stronger. Rig a cable pull line from the pin to a dash mounted knob that you pull.

The air meter box and its sampling sensor are not needed / no use if you've done like many people and disconnected the two vac pods on that side of the car. My box is currently sitting on the bench and I have a 3" straight pipe in this spot.

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Cheers!
Scott McPhee

1987 300D