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  #1  
Old 07-04-2006, 07:02 PM
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Oil in the vacuum lines

My '83 300D turbodiesel has vacuum problems (not shutting down, rough transmission, bad door locks). Though I might have some leaks, the biggest and most immediate problem in getting this fixed is the oil in my lines.I have been searching for the past couple of weeks on how I might go about fixing the vacuum system, but haven't had any luck for my symptoms. I know there are a million posts that talk about both problems, but I think my problem might be a little different.

Most posts have said that the shut off valve (specifically a broken shut off valve diaphragm) is the only place that oil can get in the system. Symptoms supporting the "bad shut off valve" theory are the following:
1. Oil in the lines
2. Car has to be turned off from under the hood.

However, symptoms that make me think it might be something else are the following:

1. There is less oil in the vacuum lines around the shutoff valve than there in other places (i.e. line coming off the vacuum pump)
2. I can attach my MightyVac to the shut off valve and provide some vacuum and it will shut off.

Any help with this issue would be greatly appreciated. Really, if somebody could let me know if there are any places besides the shut off valve that can let oil into the system that would be huge a step in the right direction.
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  #2  
Old 07-04-2006, 07:08 PM
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Its possible that the diaphragm in the vac pump is leaking.
When you shut off the engine, the vacuum persists on the engine side of the pump, and that can pull oil back into the pipe (called a manifold by many) that runs from the vac pump to the brake booster.
If the shut off valve hold vacuum (give it 2 or 3 minutes and the vac level should not drift) I would say that isn't the source of oil.
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Old 07-04-2006, 07:16 PM
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That sounds more correct to my problems, but I still get right amount of vacuum (22") from the end of the new booster vacuum line that I just installed. Wouldn't a bad vacuum pump diaphragm cause me to get an incorrect amount of vacuum?

Also, I just went outside to check to see if my shut off valve can hold a vacuum, and it looks like it does have some sort of leak. I just hope both diaphragms aren't messed up and that the oil hasn't gunked up my system more than a bottle of brake cleaner can't handle.

Last edited by ehadden; 07-04-2006 at 07:38 PM.
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Old 07-04-2006, 08:01 PM
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Quote:
Originally Posted by ehadden
That sounds more correct to my problems, but I still get right amount of vacuum (22") from the end of the new booster vacuum line that I just installed. Wouldn't a bad vacuum pump diaphragm cause me to get an incorrect amount of vacuum?

Also, I just went outside to check to see if my shut off valve can hold a vacuum, and it looks like it does have some sort of leak. I just hope both diaphragms aren't messed up and that the oil hasn't gunked up my system more than a bottle of brake cleaner can't handle.
careful with brake cleaner in the plastic lines, I don't think I would do that for fear it may melt something!
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Old 07-05-2006, 08:18 AM
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The oil in my vacuum lines was coming from the fuel shutoff valve in the injection pump.
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Old 07-05-2006, 11:23 AM
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Well, I installed a new $70 shut off valve. It looks real nice, all shiney and everything, but I don't think that was the problem because it still didn't fix my shut off. I think the problem with the shut off is that I'm not getting enough vacuum from the line to activate it, but the question is whether that is b/c of gunked up lines, a bad shut off under the dash, a leak (i don't think so), or multiple combinations of the above. Man I am in a mess! Any suggestions on what my next step should be or how I can figure out the next step? I don't want to spend another $70 on a part that I don't need.
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Old 07-05-2006, 12:16 PM
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I think Dieseldiehard nailed it. He told you the vac pump was leaking the oil. Its a pretty common failure point. The vac signal may not be much less if the tear is small, but its more than enough to suck up oil. Replace or rebuild your pump and you should be good to go.
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Old 07-05-2006, 12:22 PM
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From what you have described, you may have only fixed part of the problem by replacing the fuel shut-off. The gunk in the lines needs to be cleaned out or it will continue to cause problems.

I went through some of this on mine. The PO had the valve replaced but the "mechanic" didn't clean the system. All it will take is time and 1-2 cans of brake cleaner. Also, the oil causes the flex fittings to deteriate and causes them to leak. (about $10 replaces them all)

Remember it is a vacuum system. Changing one failed part won't necessarily cure the whole system.
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  #9  
Old 07-05-2006, 12:41 PM
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Is it possible that oil could have gunked up some other parts beyond what a cleaning job could do? Or can I just use the brake cleaner.

Also, does anybody think they have a better way to clean out this system besides the ever-so-potent brake cleaner? I think brake cleaner might not be the best solution inside some of these parts that I'm gonna try to clean out.
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  #10  
Old 07-05-2006, 01:53 PM
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If you are cleaning "parts", electronics cleaner might be a better route to take.

Brake Cleaner = 50% acetone, 30% methanol
Electronics Cleaner = 95% Heptanes
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  #11  
Old 07-05-2006, 03:09 PM
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When I say parts I'm really just talking about the shut off under the dash, which is pretty hard to get to.
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  #12  
Old 07-06-2006, 12:59 AM
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New update

Well, I have more news, but this time it makes no sense. First, new shut off valve that I put in yesterday is no longer working when I give it a vacuum with the MityVac. That is strange b/c I had it working perfectly with the MityVac as early as this morning. I guess I'll have to take it apart and see if the linkage has come undone somehow. Next, I traced a vacuum line problem to a four way splitter that comes off the booster vacuum hose and splits to the vacuum check valve (valve for locks), the green line (goes into the firewall for climate control system), and the brown line (goes into firewall to ingnition switch). The interesting thing here is that the splitter is not leaking, it gets 20" of vacuum, but when all three lines are plugged in each line barely registers getting a vacuum (I checked each one, one at a time while the other two lines were plugged in). Next, I tried bypassing the three way splitter and got 20" to each of the three lines. When I tried this the door locks didn't work (both lines from the check valve had 20"), the shutoff valve got 15" of vacuum but still didn't work, and the climate control system finally opened some of the vents that hadn't ever worked. So next step was to put each line back into the four way splitter, but this time I would do them one at a time and seel of the other openings with golf tees. When I did this I got the same results as bypassing the system. Suspecting a leak in the door locks, I tried putting the other two lines (green and brown) back in while sealing off the check valve line (aka door locks). When I did that the climate control no longer worked. Congrats if you have gotten to this point without being utterly confused.

Anyways, I have a mess and think I have gotten a lot of clues, but still can't solve the vacuum mystery. Right now, I'm pretty sure I have a leak in my door lock lines, but beyond that I can't figure out why 20" of vacuum isn't enough to work both the shutoff and the climate control vents. Tomorrow I will try again.
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