Oil Change, now slow to shut off. Fluid in shut-off valve lines and ignition?? - PeachParts Mercedes-Benz Forum

dafman · #1 02-03-2019, 10:25 AM

Hey guys. New 1980 300TD owner. 250k miles. Just did all the brakes (rubber lines, caliper rebuilds, parking brakes, pads, rotors, etc), diesel purge and filters, air filter, and an oil change (next is thermostat which is bad... engine never really warms up, I think it's stuck open).

The oil change was the last thing I did, and now it takes about 3-5 seconds to uncomfortably shut off. It used to just turn right off in less than 1 second. I did not think it was the valve, so I took the line off and put vacuum to it and it shut off immediately. I tried the same line the other way and it won't hold vacuum. That line appears to run directly to the ignition cylinder and is hooked up. The lines are in good condition, though dirty. There is a strange oil on the ignition cylinder, and almost looked like dirty brake fluid or engine oil. Is it possible that the oil pressure gauge is leaking?

There also seems to be a spot for a line that isn't there on a component I don't know what it it does, it's located on top of the ignition pump.

Doors work, ACC seems to work (can't really tell as the car never really warms up due to the bad thermostat, everything comes on and the service history of the car seems to insinuate it had work done to it), no idea on cruise control.

Took some pics:

https://imgur.com/gallery/HMuy0aO?

What is that fluid?? Oil from the gauge, perhaps?

What do you guys think?

Thank you,

Vincent

tyl604 · #2 02-03-2019, 10:35 AM

You can resize your pics and use the paper clip to attach. Think the max size is 850kb. They will then show up in your posts as thumbnails instead of very large pics. Looks like you posted url's.

The failure to cut off quickly indicates a vac loss. Check your vac lines. One especially goes in the back of your injection pump (the shutoff valve is inside); when you turn the engine off that vac line pulls a lever in the shutoff valve and turns off the engine. If it is leaking here or your shutoff valve suddenly fails to hold vac, you will have problems with the shutoff. Mine lasted for 37 years and I replaced it a year ago.

You might also remove that line and check to see that the shutoff valve actually does hold vac.

Alec300SD · #3 02-03-2019, 10:38 AM

Slow to shutdown...likely you disturbed one the vacuum connectors removing the oil canister lid to change the oil filter.

Engine oil on ignition lock...likely evidence a leak from the oil pressure gauge at some point in the past when the cluster was removed.
Could also be evidence of a leak from a previously failed diphragm on the shut off valve that has since been replaced (as yours works presently).

Mxfrank · #4 02-03-2019, 10:50 AM

When there were more older cars on the road, you'd occasionally hear about the diaphragm in the vacuum pump leaking oil into the vacuum system. This would penetrate everywhere causing widespread damage. That may have happened to your car at one time in the past. But given the circumstance, I think your current problem is just a broken vacuum connection somewhere. Now would be a good time to buy a vacuum gauge or Mityvac and learn how to track down a vacuum leak. It's not too hard...start at the pump and move forward to the system, checking pressure at every branch.

dafman · #5 02-03-2019, 10:53 AM

So I checked the valve and it works. It wont work when I hook up to the other side with my mityvac. That line seems to run directly to the ignition cylinder, but all the connections and line quality appear to be good, even on the ones around the oil filter canister that I could have disturbed. Is it possible that the leak is elsewhere from another system? Is there a decent diagram anywhere?

Clemson88 · #6 02-03-2019, 01:20 PM

https://www.google.com/search?q=mercedes+diesel+vaccum+diagrams&rlz=1C1GGRV_enUS773US773&oq=mercedes+diesel+vaccum+diagrams&aqs=chrome..69i57.18215j0j7&sourceid=chrome&ie=UTF-8

tangofox007 · #7 02-03-2019, 02:10 PM

Quote:

Originally Posted by dafman

Is it possible that the leak is elsewhere from another system?

If you applied vacuum to the downstream side of the ignition switch valve and the engine doesn't shut down, it would appear that you could rule out a possible problem with the rest of the vacuum system as the cause of your issue. That would leave the ignition switch valve and its associated plumbing as the only viable suspects.

I have had pretty much the same issue for the past several years. The engine shuts down reliably; it just takes six seconds.

Alec300SD · #8 02-03-2019, 04:39 PM

Quote:

Originally Posted by dafman

So I checked the valve and it works. It wont work when I hook up to the other side with my mityvac. That line seems to run directly to the ignition cylinder, but all the connections and line quality appear to be good, even on the ones around the oil filter canister that I could have disturbed. Is it possible that the leak is elsewhere from another system? Is there a decent diagram anywhere?

The area around last thing you touched before your symptoms developed is the likely trouble spot.
The rubber vacuum connectors near the oil canister can look fine but still leak.
The rubber degrades from age, and also heat, vibration, and oil vapors in the engine compartment.

Remove the rubber connectors (one at a time) and look closely for faint cracks when you flex the freed connector.
Many times there is a hidden crack at a branch point, or the end of the connector may have become stretched over time.
Any that unplug from their connection without significant effort should be replaced.

If the two vacuum connectors on the ignition switch are oil soaked, they should be replaced as well. BTDT.

Clemson88 · #9 02-03-2019, 04:48 PM

The best advice I've heard is to eliminate the different systems running off the vacuum pump one at a time. Pull a line, cap it off then see if the shutdown system works. It seems the natural spot to begin is at the junction in the brake booster vac line.

dafman · #10 02-04-2019, 03:00 AM

Thanks guys! First I'll do a detailed cleaning and inspection near the oil canister as suggested by Alec, then if that doesn't lead to any discoveries, I'll start capping things off. Any good sources of new vacuum lines you guys use in case I need to replace anything?

Clemson88 · #11 02-04-2019, 01:00 PM

I've order a ton of clear line from Pelican. I like using the clear and the price is good if you have time to wait on shipping across the country. I usually order stuff like that and extra filters to get free shipping.

Diesel911 · #12 02-04-2019, 03:32 PM

I did not read all of the posts so someone might have mentioned this. With age the diaphragm in the Shut Off on the Fuel Injection Pump becomes porus. One of symptoms is Oil in the Vacuum Line going to the Steering Colum Lock. If there is enough Oil it will leak out of the Vacuum Switch on the Steering Colum.

Some people continue to use the old Shut off even if it leaks some Oil. You can put a small Plastic Fuel Filter in the vacuum line between the shut off on the Fuel Injection Pump and the Vacuum Switch on the Steering Colum to catch the Oil and continue to use the old Shut Off until it fails entirely.

People have said the Shut Off on the Fuel Injection Pump is supposed to hold vacuum and not leak down. Mine leaks down and I have had some Oil in the line but it still shuts off OK.

Diseasel300 · #13 02-04-2019, 07:09 PM

Quote:

Originally Posted by Diesel911

I did not read all of the posts so someone might have mentioned this.

Sometimes it pays to read the posts. OP already confirmed that the diaphragm holds vacuum by testing with a hand tester.

Diesel911 · #14 02-06-2019, 01:00 AM

Quote:

Originally Posted by Diseasel300

Sometimes it pays to read the posts. OP already confirmed that the diaphragm holds vacuum by testing with a hand tester.

What I remember reading by the OP is he said it shut off when he applied vacuum. That is not the same as holding vacuum.

In order for Oil the OP mentioned to work up into the vacuum switch on the steering Colum it would have had to have come from the shutoff on the fuel injection pump and a pores diaphragm. That pores implies vacuum leak.

My shut off leaks oil but it shuts down fine. It does not hold vacuum but still works.

dafman · #15 02-09-2019, 08:01 PM

So it does hold vacuum. There is oil, but I believe it might be from the oil pressure gauge, as there appears to be new fittings to it, and there is old looking oil on the felt on the inside of the plastic underdash panel. I plan to get out there tomorrow and do some troubleshooting! (I couldn't get to it last week as I was away on business). I gotta get this thing ready soon, it's gonna be my daily driver!

Vincent