I still have 2 MBs. One of them is my ‘95 E300D. It I think a blew a vacuum pump since the brakes don’t work well and the engine won’t shut off until I close off the fuel filter. Where do I start to research this? Thanks for any ideas!

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dtf
1994 E320 Wagon (Died @ 308,669 miles)
1995 E300 Diesel (228,000)
1999 E300 Turbodiesel ( died @ 255,000)
2006 Toyota Tundra SR5 AC 4X4 (115,000 miles) rusted frame - sold to chop shop
2011 Audi A4 Avant (165,000 miles) Seized engine - donated to Salvation Army
BMW 330 xi 6 speed manual (175,034 miles)
2014 E350 4Matic Wagon 128,000 miles
2018 Dodge Ram 21,000 miles

This is per my 1981 300SD but might relate to your 300D - not really sure but maybe.

Sounds like a bad shut off valve. It is located inside the injection pump at the back near the firewall. You need to remove the VCV - vacuum control valve - (carefully) just above to get to it. The shutoff valve has a hook; when you turn the ignition off, vac is supposed to actuate the hook and shut down the engine. However you might test it first - hook up a Mityvac to the nipple on the shut off valve and start the engine - if you pump up the Mityvac it should immediately stop the engine. If not, the shut off valve leaks and needs to be replaced.

It could also be the two nipple ignition vac switch but the almost never fails.


Try this: How to Repair Your Shutoff Valve https://dieselgiant.com/repairyourshutoffvalve.htm

Ugh thanks for getting back so well and so fast. I will research this before I bring it to MetroDiesel to replace a vacuum pump.

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dtf
1994 E320 Wagon (Died @ 308,669 miles)
1995 E300 Diesel (228,000)
1999 E300 Turbodiesel ( died @ 255,000)
2006 Toyota Tundra SR5 AC 4X4 (115,000 miles) rusted frame - sold to chop shop
2011 Audi A4 Avant (165,000 miles) Seized engine - donated to Salvation Army
BMW 330 xi 6 speed manual (175,034 miles)
2014 E350 4Matic Wagon 128,000 miles
2018 Dodge Ram 21,000 miles

If brakes are affected, DO NOT START THE CAR BEFORE YOU CONFIRM THE REPAIRS NEEDED.

if the pump has failed, it can DESTROY the motor.

I would pull the belt and all accessories off the front of the motor, pull the vacuum pump and inspect the actuator arm bearing, and the warble plate on the timing gear.

If one or both are damaged, you need to replace them.

Seriously, do not start the car before you inspect this.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

You could also buy one of those hand pump vacuum testers, perhaps a vacuum line is bad, or slipped off somewhere. You can hook it into the system, create vacuum, and listen or test various components/lines/etc to see how quickly they lose pressure.

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1990 300d 2.5 turbo
1995 E300d

and Vstech has the best advice. DO NOT START THE ENGINE!


I've never heard of a vac leak so extreme as to cause brakes to fail but I'd still run a check on the system before I pulled the pump.


Imo, vac pumps should be replaced or rebuilt before they fail.

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84 300SD
85 380SE
83 528e
95 318ic

Finally remembered - it is the VCV that you must remove to get to the shutoff valve. If you decide the pump is not bad and need to get to the shutoff valve, the VCV must be removed. I have done it a couple of times and it is not too hard if you follow the (I think) DieselGiant instructions from the link.

Let us know what happens. Interested.

PS - you need to buy a Mityvac if you have one of our diesels. Comes in handy for door locks, engine, etc.