I have an '82 300sd where the shutoff valve was recently replaced by the PO. After replacement the car would run to full throttle in neutral or park once it was warmed up. Even will all the linkage disconnected. Several other MB diesel owners reported to me that an improperly installed vacuum shut off could do this. I removed and reinstalled the valve myself verifying it was hooked correctly in the pump with the same results, once warmed up it was off to the races. I then removed the pump and took off the back plate. One look inside and I realized any repair here was way beyond the scope of my ability. I reinstalled the pump, timed it and left the shut off valve out (temporarily sealed the opening). Same problem, once warmed up will run to redline. So improperly installed valve is ruled out. Unless someone has a suggestion on what else to check I am looking for a good used pump.

Thanks for any advice.

David
'82 300sd 265k

Your vacuum shut-off should be removed and properly installed. It's a wonder you can drive the car. If you can.
When installing the shut-off vac., make sure the hook on the shut-off lever hooks on to the shut-off rack inside the pump. You can't see this hook inside the pump, but you should be able to tell when it is in the slot by pulling back on the shut-off valve. Good luck.
Bill Lewallen Lexington,Ky.

When you hook up the valve and then apply a hand pump to the shut-off valve, do you see the emergency shut-off arm, come down to the off position?

I think you all are missing the problem here. It has nothing to do with how the shut off valve was installed or even IF it is installed. Without the valve in place the engine is going to full throttle. Problem apparantly is in the internal IP linkage somewhere.

David
'82 300SD

David,
Have you ever installed a vacuum shut-off valve on a 1982 300SD ,or a plain 240D or a 300D? The shut off is the same.
If not properly installed, The engine will race to full RPM.I did it once and it scared the heck out of me. I now make sure the shut-off is caught on the lever inside the pump. I have installed many, many of them. Easy to do. Takes maybe thirty minutes. I usually keep three of them on hand. The part No. is 000 070 20 53. I pay $35 for them.
Bill Lewallen Lexington,Ky.

David,
I do understand the problem, but we must also understand that the valve and the rack work together as one unit.
The SO valve works in conjunction with the rack. If the valve is not installed there is no resistance so the rack will turn up causing the engine to run at full throttle. The same condition will happen if the valve is not hooked/installed properly.

CJ I will have to disagree with your assesment. If you look at the diagram of the internal linkage in the manual you will see that under normal operating conditions the hook on the end of the SO doesn't even touch the lever in the pump. From what I can see the only time the SO hook makes contact is when vacuum is applied and the hook retracts catching the lever to pull the control rack to the shut down position. If someone that has an intimate knowledge of or Bosch formal training in the internal workings of the IP linkage wants to respond to this I would appreciate the input.

I believe that the full throttle problems described by others with an incorrect installation of the SO unit is when the SO hook is on the wrong side of the lever pushing it to full throttle.

David
'82 300sd 265k