Oil in Engine Shutoff Valve 300sd - PeachParts Mercedes-Benz Forum

cousindave76 · #1 01-10-2007, 03:55 PM

I have an 83' 300sd that has had trouble shuting down lately. I have a brake booster giving me trouble as well, so I figured the loss in vacuum from the brake booster is causing the engine shut off valve to not have enough vacuum to shut the engine down.

I diconnected the brake booster from the main vac line and hooked a vacuum gauge up to the line. Car running I get about 20"hg at the brake booster side of the main vac line. I shut the key off and I still get a long drawn out shutoff.

If I press the manual shutoff lever it stops running imediatly.

I decided to hook my mighty-vac(best tool ever) up to the shutoff valve directly and see if that shuts it down normaly.

With the car running I turned the key off and reached for the mighty-vac. I gave it two quick pumps and the vac gadge jumped up to about 15"hg. This shut the engine off right away. So it seems I need to look else where for my problem... or do I? .....

...I noticed when I aplied vacuum to the shutoff valve, OIL(not fuel) came out of it. The oil was climing up the clear vacuum line. It made it about 6 inch's up the line before I released the vacuum on the Mighty-Vac.

Is this a normal thing to happen when you apply a little to much vacuum the the shutoff valve? Did I damage it? Does the oil indicate the valve is bad or that shomething leading to the valve is bad, feeding oil into the vac system?

I appreciate your input.

rrgrassi · #2 01-10-2007, 04:11 PM

That is usually a sign that the vaccuum pump diaphragm has a tear in it, allowing engine oil to enter the vacuum system.

If the pump was rebuilt by some one else, that means they did not take the time to clean the lines. Engine oil in the vac system will cause all sorts of problems, including ruining a brake booster.

leathermang · #3 01-10-2007, 04:14 PM

99 percent chance your vacuum pump diaphram has a leak in it... that is the usual way in which oil gets to those places... also check your pipe which goes into the inside of your air cleaner ...if you have that ... if you see oil up there coming out of that line it means the diaphram is bad on the vacuum pump... those other indicators go along with that also..

cousindave76 · #4 01-10-2007, 04:17 PM

Quote:

Originally Posted by rrgrassi

That is usually a sign that the vaccuum pump diaphragm has a tear in it, allowing engine oil to enter the vacuum system.

If the pump was rebuilt by some one else, that means they did not take the time to clean the lines. Engine oil in the vac system will cause all sorts of problems, including ruining a brake booster.

Can my vacuum pump have a tear in the diaphragm and still put out about 20"hg? I agree with oil in the line causing all sorts of problems. I'm just trying to figure out where the oil is coming from.

I had removed my brake booster yesterday and did not see any signs of oil getting into it. It went bad on it's own.

I know the IP gets oiled somehow. I'm wondering if the shutoff valve would have access to this oil somehow. In other words, is the fact that oil came out of my shutoff valve mean that there is oil getting into the valve from the vacuum pump? Or does that mean the shutoff valve is bad and oil is leaking from the IP to the vacuum system?

cousindave76 · #5 01-10-2007, 04:19 PM

Quote:

Originally Posted by leathermang

99 percent chance your vacuum pump diaphram has a leak in it... that is the usual way in which oil gets to those places... also check your pipe which goes into the inside of your air cleaner ...if you have that ... if you see oil up there coming out of that line it means the diaphram is bad on the vacuum pump... those other indicators go along with that also..

Well okay then. That sounds pretty positive to be the vacuum pump. I guess since it is working, my only option to figure out if that is the problem or not is to rebuild it.

Anyone know a good way to clean out the oil that got into my vacuum lines?

leathermang · #6 01-10-2007, 04:24 PM

I am guessing here... but if the vacuum loss is at the brake booster... there should be some one way valves in the system to where if the system is really pulling 20 inches you should only have one problem... the booster ... it is not easy to find the pictures and proper valves to get it back to original... but some have managed to do it.... the combo of oil in lines and booster not boosting and shutoff problems almost always indicates vac pump diaphram problems...

rrgrassi · #7 01-10-2007, 04:24 PM

Disconnect all the lines and cean them individually with carb or brake cleaner. You do not want that stuff getting into the vacuum pods, though.

A vacuum pump can still operate when it is leaking. That depends on how big the leak it.

The IP is oiled from the engine, but the shut off valve stops the flow of fuel. IIRC, the shut off valve does not get any lube from the IP or the engine.

leathermang · #8 01-10-2007, 04:27 PM

First fix whatever is causing oil to get into them....
then I would take them apart and squirt WD40 into them and the air pressure to move it on out ...hold on to the end to keep from getting a facial ....
probably brake cleaner is fine but harsh if you get it on you....

DeliveryValve · #9 01-10-2007, 04:34 PM

Quote:

Originally Posted by rrgrassi

The IP is oiled from the engine, but the shut off valve stops the flow of fuel. IIRC, the shut off valve does not get any lube from the IP or the engine.

On the contrary you can get oil leaking from the shutoff valve it is a common problem.

The valve's arm goes inside the IP and when the diaphram is bad sucks in oil.

http://www.dieselgiant.com/repairyourshutoffvalve.htm

See this discussion for more info.

How can I change shutoff valve. Need advice

I'd check this also.

cousindave76 · #10 01-10-2007, 04:36 PM

I'm starting to think I happen to be having more than one problem at the same time.

I know my booster is bad. I am going to have it rebuilt.

I have plenty of vacuum to run all the systems in my car until I press the brake. Since I have a bad booster I lose almost all vacuum and some systems start to fail until I take my foot off the brake.

I do not notice oil an any other line except the one going to the shutoff valve. This is leading me to believe that the shutoff valve diaphragm is bad too!

Does this seem likely?

I took the main vac line off of my vac pump and while it was not wet with oil, there was some black residue. Is this an indication that in all of this my vacuum pump is ALSO having a diaphragm issue?

wow, to many things all at once. And just for fun, I thought I'd add that my heater core started leaking today. You can now congratulate me, I am DEEP in the MB club now! YIKES!

rrgrassi · #11 01-10-2007, 04:37 PM

Quote:

Originally Posted by rmarzan

On the contrary you can get oil leaking from the shutoff valve it is a common problem.

The valve's arm goes inside the IP and when the diaphram is bad sucks in oil.

http://www.dieselgiant.com/repairyourshutoffvalve.htm

See this discussion for more info.

How can I change shutoff valve. Need advice

I'd check this also.

See, I just learned something new, and stand corrected.

Thanks!

cousindave76 · #12 01-10-2007, 04:41 PM

Quote:

Originally Posted by rmarzan

On the contrary you can get oil leaking from the shutoff valve it is a common problem.

The valve's arm goes inside the IP and when the diaphram is bad sucks in oil.

http://www.dieselgiant.com/repairyourshutoffvalve.htm

See this discussion for more info.

How can I change shutoff valve. Need advice

I'd check this also.

Thanks rmarzan!

I do think my shutoff valve is leaking. Thanks also for the link, looks like I will be doing this repair job.

CHEERS!

Icefire · #13 01-10-2007, 04:49 PM

Quote:

Originally Posted by cousindave76

Thanks rmarzan!

I do think my shutoff valve is leaking. Thanks also for the link, looks like I will be doing this repair job.

CHEERS!

Another way to tell if your shutoff valve is leaking might be to use a long vacuum line pull a vacuum then see if it holds or not, If not and oil is heading towards your mittyvac, then you have found your problem, If it holds vacuum then keep looking

rrgrassi · #14 01-10-2007, 04:54 PM

Check the line between the vacuum pump and booster for oil. If none, it could be just the shut off valve is leaking. If there is oil there too, then it will be worth it to rebuild the vacuum pump as well.

That can also be why it takes a while to shut down. The oil while flowing is also plugging the hole enough to allow the vacuum to pull the shut off valve diapragm...Kinda like how taking a pull on a really thick milkshake can collapse a straw, while still getting the milkshake out...

kerry · #15 01-10-2007, 05:46 PM

I'm chasing a similar problem at the moment on the 77 300d. Booster not boosting adequately and shutdown slow. But I have 18" of vacuum when I test the system (at a mile high). But I did notice some oil in the hose to the shutdown valve. I replaced the shut down valve on this car about a year and a half ago so I think it must be still good. I'm thinking a small tear in the vacuum pump diaphragm. But I'm puzzled how that affects the booster when the vacuum reading is still normal. Mit Vac shuts down the engine pronto.

There 's more than the two of us with a similar problem right now. Barry may be right that mechanical demons migrate around the universe doing their evil deeds the same way in different places at the same time.