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  #1  
Old 11-05-2006, 11:54 PM
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W123 Oil? in ignition switch/Engine shuts off normally

Ok, I have a 1985 300D, 154K on the clock. I needed to replace the ignition switch, for I was having to do the little "key jiggle" thing to get my Climate Control to come on. Well, after pulling the dash (had to repair vacuum pods, too), I pull the ignition lock assembly and notice a little oil in the switch (didn't think much about it, then). The little shaft on the back side of the ignition lock assembly that goes into the switch was cracked. I order a whole new assembly from Phil at Fastlane and install it.
I was concerned about this oil I saw in the switch, so I do a search here, and now, I'm wondering if either my injection pump shut off is bad, or was the ignition shut off switch located on the ignition lock bad, or do I have a problem with my vacuum pump diaphram? I really don't want to ruin this new $150 ignition assembly I just installed. Like the title of the post says, the car shuts off normally, so I'm thinking the injection pump shut off is OK. The car shifts OK, door locks work, most of the climate control vacuum elements work, and performance seems normal, so I'm thinking the vacuum pump is functioning OK. I wonder if this was just a bad vacuum shut off located at the ignition lock. Any help will be greatly appreciated.
Thanks

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'85 300D 190K miles
running on B100 Biodiesel since 156K, SCRATCH THAT! I can only find Biodiesel at 1 location in Houston! (not very convenient)
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  #2  
Old 11-06-2006, 12:24 AM
bgkast's Avatar
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I bet you have a small hole in your shut off diaphragm. If you have a mighty vac hook it up to the shut off port on the back of the injection pump and see if it will hold vacuum...I bet it will have a slow leak.

The oil can damage the vac lines and fittings, and possibly the valve on the lock assembly, but not the lock assembly its self.
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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

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  #3  
Old 11-06-2006, 12:33 AM
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Yeah do some vac tests and check other vac lines for oil presence. I wonder if you can trace back the line to ignition and open it up at the engine bay. Then spray break cleaner fluid inside the line and force air through to clean out.

You are on the right track being proactive that is for sure.

Pulled the dash out.... man that must have been an ordeal !! How much time did it take??

good luck.
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  #4  
Old 11-06-2006, 01:23 AM
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Pulling the dash was really not that difficult.

This may be a really stupid question, but, this injector pump shut off is the injector for the diesel into the engine, right? So why, if it has a hole in its' diaphram, does it force oil into the ignition switch/and/or the vacuum lines?
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'85 300D 190K miles
running on B100 Biodiesel since 156K, SCRATCH THAT! I can only find Biodiesel at 1 location in Houston! (not very convenient)
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  #5  
Old 11-06-2006, 01:30 AM
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Quote:
Originally Posted by Flyin4now View Post
Pulling the dash was really not that difficult.

It comes out a lot easier than it goes back in......
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  #6  
Old 11-06-2006, 01:35 AM
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JimmyL, thanks for the words of encouragement!
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'85 300D 190K miles
running on B100 Biodiesel since 156K, SCRATCH THAT! I can only find Biodiesel at 1 location in Houston! (not very convenient)
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  #7  
Old 11-06-2006, 03:36 AM
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Quote:
Originally Posted by Flyin4now View Post
Pulling the dash was really not that difficult.

This may be a really stupid question, but, this injector pump shut off is the injector for the diesel into the engine, right? So why, if it has a hole in its' diaphram, does it force oil into the ignition switch/and/or the vacuum lines?
When vacuum is applied to the diaphragm it closes the rack (I think) and cuts off fuel. If there is a small hole in the diaphragm it will still close the rack, however engine oil that is used to lubricate the pump can be sucked into the vacuum line. Eventually the suction allows the oil to work its way to the "ignition" switch, then on toward the vacuum pump.
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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine
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  #8  
Old 11-06-2006, 07:51 AM
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I think I am working with the same problem. I have oil residue in all my lines but the valve works fine. The bizzar thing is that I have oil in everything including the climate control vac pods. I would think under vacuum, the oil would go right back to the pump, but somehow it's worked its way all over.
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  #9  
Old 11-10-2006, 12:05 AM
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Well, I hooked up the Mityvac to the shut off. I could hardly tell if the gauge lost pressure, or not. How much vacuum should I pull on it tell if it's leaking. How long would it take to show a difference on the gauge if it had a slow leak? Sorry, but I'm still a newbie at this vacuum troubleshooting stuff.

Thanks
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'85 300D 190K miles
running on B100 Biodiesel since 156K, SCRATCH THAT! I can only find Biodiesel at 1 location in Houston! (not very convenient)
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  #10  
Old 11-10-2006, 12:29 AM
ForcedInduction
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I use a clear fuel filter inline with the shutoff valve. It will give me an early warning of a bad diaphragm and prevent (or at least slow) oil from contaminating anything else in the system.
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W123 Oil? in ignition switch/Engine shuts off normally-vac-filter.jpg  
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  #11  
Old 11-10-2006, 08:02 AM
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Well, I was just about to make a post asking why the radio I swapped out last night was coated in oil -- now I've got a clue about the cause(s). I guess I've got a leak in the shutoff diaphragm and leaks in the HVAC controls.

I really like that filter idea, ForcedInduction. It probably serves as a small trap as well.

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