Replacing Vac Shutoff on 617 - PeachParts Mercedes-Benz Forum

JamesDean · #1 10-06-2010, 11:50 AM

Hello all,

I've got a replacement vac shutoff unit for my one 300SD, I've never tried replacing one of these before. It doesnt look bad. FSM made it seem easy. It just looks like getting down to all the bolts and getting the thing out of there will be difficult. Is just seems like theres not enough room back there..

anyone done this before?

thanks,

kris

toomany MBZ · #2 10-06-2010, 11:58 AM

Yes, the one bolt farthest away can be a bit tricky to get to, but the swap didn't take me long.

Diesel911 · #3 10-06-2010, 12:13 PM

Quote:

Originally Posted by JamesDean

Hello all,

I've got a replacement vac shutoff unit for my one 300SD, I've never tried replacing one of these before. It doesnt look bad. FSM made it seem easy. It just looks like getting down to all the bolts and getting the thing out of there will be difficult. Is just seems like theres not enough room back there..

anyone done this before?

thanks,

kris

It seems like an easy job but several Members have ended up with a runaway Engine.
2 that end prepare to shut the Engine down by blocking the Turbo or Manifold intake with a piece of Wood or stopping the Fuel Supply (much slower).
What happen is the if the bent part does not go into the slot on the Fuel Rack inside of the Fuel Injection Pump the Rack gets pusned into the Full Fuel position.
Also if you are replacing the Gasket use the same amount of Gaskets on it.

whunter · #4 10-06-2010, 01:16 PM

Quote:

Originally Posted by JamesDean

Hello all,

I've got a replacement vac shutoff unit for my one 300SD, I've never tried replacing one of these before. It doesnt look bad. FSM made it seem easy. It just looks like getting down to all the bolts and getting the thing out of there will be difficult. Is just seems like theres not enough room back there..

anyone done this before?

thanks,

kris

Read this first.

Run away diesel, why does it happen?
http://www.peachparts.com/shopforum/showthread.php?t=101404

.

toomany MBZ · #5 10-06-2010, 01:41 PM

Pay attention to the orientation of that hook when you remove it.

Take your time, note the orientation of the vacuum line too, take pics first.

Folks that experience a run away because of this don't pay attention to how it was on in the first place.

Did I mention to pay attention to the orientation of the vacuum line and hook as you're removing the actuator?

bobodaclown · #6 10-06-2010, 01:53 PM

Do a dry run first. Hook up your mighty vac to actuate the shut off valve. Make sure that every things operates the way it should.

toomany MBZ · #7 10-06-2010, 06:45 PM

^ I did that, worked fine.
I found oil dripping out of the ignition switch, replaced the shut off actuator, no more problem shutting the engine off with the key and no more oil drip.

JamesDean · #8 10-16-2010, 12:51 PM

Thanks guys for all the advice, I just did this job today. It was much easier than I thought it was going to be.

Heres pretty much what I did:
1) remove vacuum lines
2) remove vacuum switch thing (2 alan heads)
3) take off 4 10mm bolts that hold plate on
4) remove old solenoid
5) install new seals on replacement unit
6) push rod into unit, place finger on vacuum port..
7) install, release port, make sure that you cannot rotate the unit freely, it should lock into a track
8) bolt everything back down

To prevent a run-away incident, i disconnected the fuel lines and left some fuel in the prefilter..I figured, if it wouldnt shut off by key, it would shut off when the fuel was out.

Worked first time, no run-away incident.

yay.

Thanks!

Diesel911 · #9 10-16-2010, 03:17 PM

Nice clear write up!

dmorrison · #10 10-17-2010, 01:11 AM

Here is a positive way to ensure the shut off valve is connected so you don't get a runaway.

http://www.peachparts.com/shopforum/showthread.php?t=151322&highlight=engine+shutoff+valve+dave

Dave