Shut-Off Valve @ IP aka Vacuum Control Unit or MB FSM-EPC = shutoff box
 

A local parts supplier supplied me this part which looks the same as the one in the CD manual for W123 300DT. I have not taken out the old part (does not hold vacuum and leaks oil into the vacuum line), which I plan to do when the weather improves, to compare it's likeness.

My hesitation is, the part has a stamped on it that says "ronak" and that's it! No part number; No star. I tested it with MityVac and it seems to hold vacuum pulling the lever in which indicates that the diaphragm is okay.

Has anyone heard about "ronak"? Is this an OEM part or of the same quality?

Thanks.

P.S. The photo looks the same as what I received but the stamped labelling is not.

That looks like the right part, don't know about the brand though. When you tested it, how many pumps did it take before the arm was fully retracted, and what was the reading on the gauge? I ask because I'd like to know how a good one is supposed to act when tested. Thanks.

You probably know this but,,,
 

Make certain when reinstalling this part that you get the hook onto the rack arm. If you miss this connection all kinds of bad things can happen.

I like many here always keep a couple of 17mm wrenches handy when first starting the car afte doing anything to the IP so that if needed you can start cracking injection lines as fast as possible to kill the motor.

WM20650:

Two full strokes takes the vacuum reading at 6-7" and fully-retracts the lever on the shutoff valve. It holds the vacuum and kept the lever retracted for more than 2 minutes (that's how long I waited).

Photo of it using the Mity Vac

FYI
 

MB FSM and EPC calls this a shutoff box.


.

That is the correct type, with the bent arm. How much did you pay? I see prices from $55 to $200 for new ones. There are ones that look similar for earlier or later engines (forgot) that have a pin at the end instead of the bend and cost much less. There should be 2 gaskets w/ a steel shim between the stop valve and injection pump. You can buy the gaskets separately real cheap.

If the stop valve doesn't leak when you pull a vacuum, it is good. If your car has only ~10" Hg vacuum as both my 300D's did recently, even a good one will be very marginal in shutting off the engine, taking 10 sec or not at all. After fixing/replacing the vacuum pumps and getting a steady 20" Hg, both engines turn off immediately.

Replacing one is easy if you have a set of ratcheting box wrenches (Craftsman ~$35). I recall the 3 hex bolts have 10 mm heads. Remove the white transmission control valve on top of the injection pump first. You need to snake the stop valves behind the oil filter housing to get them in or out of place, which is easiest if you suck the rod in with your MightVac.

As mentioned, insure the hook goes around the arm in the IP arm, which you can't see. When correct, you can push the stop valve forward and won't feel it pushing anything. If you tug backwards, you will feel it catch on the arm. It isn't hard to get it right and someone would have to be inept to force it forward against the arm using the bolts. That would leave the pump at "high throttle" and I imagine one then couldn't push the manual "stop" lever full forward. If correct, you can easily slide the stop valve into the IP pump and snug the bolts up with 2 fingers, assuming you were smart enough to clean them and spray w/ WD-40.

I have removed several of the vacuum shut off valves or Shutoff box in the yards. just pulled one yesterday off a 85 300D.

There are the 4 10mm bolts to remove, then the square plate, gasket, steel ring, gasket and finally the valve. several I removed only had one gasket.

There really isn`t room to use a ratching box wrench or Gear Wrench. I use a 1/4" wratchet and a 10mm socket to loosen the bolts, then remove with my fingers. on the 617 engine, the top left one (Or looking down from the top of the engine, top right) is close to the Oil Filter housing. If you loosen it too far, the wratchet is up against the housing, and you can`t get it out w/o screwing the bolt back in a bit. Also a bit tight getting your hand in between the filter housing. The 240D`s give plenty of room.

The one yesterday, the PO used lock-tite and it was a little more difficult to remove the bolts.

Here is a thread showing how the lever hooks inside the IP, posted by "THEGEARS".
http://www.peachparts.com/shopforum/diesel-discussion/299608-vacuum-shut-off-device-pics.html


Charlie

One of the aftermarket parts companies makes them MTC. Some parts places sell the offical one and one and the afetermarket ones made in ????