My 300SD wont SHUT OFF ?? - PeachParts Mercedes-Benz Forum

pantherpaw · #1 01-10-2008, 08:41 AM

1983 300SD - 5 Cylinder Diesel - What device turns off the engine, and how can I check it. I'm guessing its a vacuum operated fuel valve of some sort...Anybody know how to solve this problem...?

TX76513 · #2 01-10-2008, 08:44 AM

Hey Georgia
Pull the hard brown line off your engine shut of valve (on IP) and attach your miti vac. With engine running pull a vacuum on SOV. If engine fails to turn off replace your SOV.

The SOV looks like this on your car.

pantherpaw · #3 01-10-2008, 08:54 AM

I'm going to the link right now to check it out. How much does an SOV cost these days?

TX76513 · #4 01-10-2008, 08:56 AM

$129 here on Fastlane

vstech · #5 01-10-2008, 08:58 AM

they rarely fail, more than likely, it is a vacuum leak. when you pull the brown line off, look inside for evidence of motor oil in there, if it's got oil, you found the problem, replace the valve. if not, use a vacuum gauge and start tracking down vacuum leaks. start closest to the pump and work your way back.

kerry · #6 01-10-2008, 08:59 AM

If you don't have a Mity Vac, put a long piece of vacuum hose on the valve in place of the brown vacuum line and suck on it. If it shuts the engine down, the valve is ok and the leak is elsewhere. This is the most common situation.
Shut off valve won't look quite like that on the car. It's hard to see, down between the back of the injection pump and the front of the oil filter housing.

Depending on the amount of redneck in your genes, you could simply run the vacuum hose out of the engine compartment at the cowling, leaving about a foor or so protruding. You can then shut off the engine without opening the hood by simply giving two quick sucks on the line.
If your redneck heritage is less, you could take the time to thread the vacuum hose thru the firewall leaving it accessible to suck in the passenger compartment.
If you have a long dignified family line, you'll have your footman seek out the system's vacuum leak and repair it.

pantherpaw · #7 01-10-2008, 09:08 AM

I think I'll just fix it, or maybe my girlfriend can help too...She's from Alabama.

westkill · #8 01-10-2008, 09:15 AM

or here

http://www.***************/search/product.aspx?sid=x2dmdj45iufrj255tswf5055&makeid=800016@Mercedes&modelid=1193778@300DT&year=1983&cid=22@Fuel%20%26%20Air%20System&gid=6061@Diesel%20Shutoff%20Solenoid/Valve

TX76513 · #9 01-10-2008, 09:18 AM

Quote:

Originally Posted by westkill

or here

http://www.***************/search/product.aspx?sid=x2dmdj45iufrj255tswf5055&makeid=800016@Mercedes&modelid=1193778@300DT&year=1983&cid=22@Fuel%20%26%20Air%20System&gid=6061@Diesel%20Shutoff%20Solenoid/Valve

That's an excellent price.

kerry · #10 01-10-2008, 09:23 AM

The odds of it being a bad shut off valve are low. There are probably 6 vacuum diaphragms in the vacuum circuit associated with the shut off mechanism and many more connections. A failure in any of the diaphragms or a disconnected line will reduce the vacuum level enough to cause the shut off valve to malfunction.
The simply one minute test I described can confirm if it is your shut off valve or if the problem is elsewhere.

The typical problem that shows up here quite often is that someone just changed their oil, now the engine won't shut off. They dislodged a vacuum line when changing the oil filter. You didn't happen to change your oil recently?

300cdT · #11 01-10-2008, 09:23 AM

Quote:

Originally Posted by pantherpaw

I think I'll just fix it, or maybe my girlfriend can help too...She's from Alabama.

shes from alabama. thats great

gl with the fix. seems a bit crazy that that little piece of metal can cost over $100 eh? german engineering=$$$

pantherpaw · #12 01-10-2008, 09:25 AM

Quote:

Originally Posted by TX76513

That's an excellent price.

That price IS great...

pantherpaw · #13 01-10-2008, 09:29 AM

Quote:

Originally Posted by 300cdT

shes from alabama. thats great

gl with the fix. seems a bit crazy that that little piece of metal can cost over $100 eh? german engineering=$$$

Actually, I agree with KERRY, it seems dumb to spend 50 or 100 bucks when simple rig would work...I think I can just run the line into the cabin, and leave my MitiVac hooked up and lay it in the seat next to my Smith & Wesson...

pantherpaw · #14 01-10-2008, 09:53 AM

Quote:

Originally Posted by 300cdT

shes from alabama. thats great

gl with the fix. seems a bit crazy that that little piece of metal can cost over $100 eh? german engineering=$$$

what year is your 300ctd? Is that it in the avatar photo? Thats a nice car.

vstech · #15 01-10-2008, 10:24 AM

Quote:

Originally Posted by pantherpaw

Actually, I agree with KERRY, it seems dumb to spend 50 or 100 bucks when simple rig would work...I think I can just run the line into the cabin, and leave my MitiVac hooked up and lay it in the seat next to my Smith & Wesson...

um, actually, if the 50-100.00 fix would work, then the hose rig would not... the hose rig assumes there is a leak, and bypassing the vac circuit shuts off the car.