Suddenly leaking a lot of oil from air filter housing - Help!!! - Page 2 - PeachParts Mercedes-Benz Forum

kerry · #16 06-12-2007, 07:20 PM

"coming out of the manifold intake underneath the oil filter housing"

That's what confused me in your original post. I guess you meant 'air filter housing'.

The vacuum pump is on the front of the engine left side. The diaphragm can be relaced with the pump assembly on the engine. There are two check valves that can be replaced at the same time. Probably need to remove the fan to get access. There's a plastic hose running from the pump to the air filter housing. Looking at that hose should tell you if the diaphragm has failed.

I believe that there is also a check valve at the bottom of the return line at or near the pan. I suppose a failed check valve could possibly allow oil to be pushed back up that tube should crankcase pressures be high enough.

rino · #17 06-12-2007, 07:45 PM

Quote:

Originally Posted by kerry edwards

"coming out of the manifold intake underneath the oil filter housing"

That's what confused me in your original post. I guess you meant 'air filter housing'.

The vacuum pump is on the front of the engine left side. The diaphragm can be relaced with the pump assembly on the engine. There are two check valves that can be replaced at the same time. Probably need to remove the fan to get access. There's a plastic hose running from the pump to the air filter housing. Looking at that hose should tell you if the diaphragm has failed.

I believe that there is also a check valve at the bottom of the return line at or near the pan. I suppose a failed check valve could possibly allow oil to be pushed back up that tube should crankcase pressures be high enough.

Thank you for pointing out my confusing description ("oil" instead of "air")... I just corrected the original post.

So, let's say that when I go home tonight and check the car, I find that the the plastic hose from vacuum pump to air filter housing contains oil (is black)... What do I do at this point? Do I need to look at the diaphragm also, or just go ahead and get a new diaphragm and replace it? Also, you mentioned two check valves that can be replaced at the same time... Do I need to replace those also? Or how do I find out if I need to?

Could it be a check valve alone causing this problem, and not the diaphragm?

Sorry for all these questions, but I have no experience working on the vacuum pump and would appreciate your being as specific as possible.

Thanks...

slarson80 · #18 06-12-2007, 08:57 PM

I took when I did mine. The kit was really cheap. There are actually two kits, one is just the diaphgram and hardware needed to replace it. The other is for the check valves. I just did the diaphragm. Keep in mind this is not a pictorial, just some pix. Hope it helps.

Vacuum pump diaphragm replacement pix

vstech · #19 06-12-2007, 10:35 PM

so the vac return line to the air filter lid is black hmm? odds are pretty good that you have found the source of the oil. be sure and post pictures of what you find, and go ahead and take pics of the repair procedure.
glad I could help with the diagnosis.

kerry · #20 06-12-2007, 11:39 PM

Quote:

Originally Posted by rino

Thank you for pointing out my confusing description ("oil" instead of "air")... I just corrected the original post.

So, let's say that when I go home tonight and check the car, I find that the the plastic hose from vacuum pump to air filter housing contains oil (is black)... What do I do at this point? Do I need to look at the diaphragm also, or just go ahead and get a new diaphragm and replace it? Also, you mentioned two check valves that can be replaced at the same time... Do I need to replace those also? Or how do I find out if I need to?

Could it be a check valve alone causing this problem, and not the diaphragm?

Sorry for all these questions, but I have no experience working on the vacuum pump and would appreciate your being as specific as possible.

Thanks...

If there's oil in the line, I'd order both the diaphragm and check valves. No reason not to replace the check valves while you have it open.
Takes an hour or so to rebuild it.

slarson80 · #21 06-13-2007, 12:05 AM

Just because I did not change my check valves does not mean you should not. My case was much less severe, if I had oil dripping from my air cleaner. I would have changed mine too. OK probably should have anyway, but so far, so good....

cdplayer · #22 06-13-2007, 12:29 AM

Quote:

Originally Posted by rino

I've owned my '79 240D for over two years now... and this problem started happening a couple of weeks ago: even after a short trip, there is a large puddle of engine oil on the ground, as soon as 10-15 minutes after parking the car (and the oil keeps dripping, at a decreasing speed for several hours).

I immediately found out that the oil was dripping down from the small holes on the bottom of the air filter housing, that is, coming out of the manifold intake underneath the air filter housing and being pushed through the air filter (which gets totally soaked with oil), then accumulating there and leaking out of the tiny holes.

First thing I did was to clean out the filter housing and put in a new air filter, thinking that perhaps the old filter had been clogged and thus causing the problem. No use: that same evening, same puddle of oil near the front right wheel. Next I tried changing the engine oil (perhaps the old oil was causing the problem, I thought) and, again, replacing the oil-soaked air filter with a new one. All the same, no use: the problem, apparently, is getting even worse with time.

Yesterday I took the car on a 100-mile trip on the highway. I stopped a couple of times for just a few minutes and each time there soon was a H-U-G-E puddle of oil underneath the car. After the trip I had to add 1 quart of oil to bring the level back to where it was before taking the trip.

Some time before this problem occurred, I had done a valve clearance adjustment - could there be any connection? Also, I had replaced the old air filter (a model that fit very loose) with a new one that fit more tightly (the filters I put in after that have been of the tighter kind).

The car performs great, is very powerful and sounds good...

What is going on?

Rino

This happened to me too with my first Mercedes. A 300CD. Turns out the vacuum pump diaphram wore out, and was letting oil pass through it. Then the oil was being pumped into the air breather, and into the vacuum lines inside the car. What a mess to clean up. I think I had to dismantle four of the dashpots inside the car to clean the oil out. After that all my vacuum thingys worked again.

Stevo · #23 06-13-2007, 12:32 AM

When you replace the small bolt in the center of the new diaphragm DONT OVER TIGHTEN IT. It doesn't take much torque.

rino · #24 06-13-2007, 11:34 AM

Quote:

Originally Posted by slarson80

I took when I did mine. The kit was really cheap. There are actually two kits, one is just the diaphgram and hardware needed to replace it. The other is for the check valves. I just did the diaphragm. Keep in mind this is not a pictorial, just some pix. Hope it helps.

Vacuum pump diaphragm replacement pix

Thanks a lot! In that article you mentioned that you removed the radiator in order to work on the pump. Does anyone know whether it is possible to work on it by just removing the fan/housing on a '79 240D?

Quote:

Originally Posted by vstech

so the vac return line to the air filter lid is black hmm? odds are pretty good that you have found the source of the oil. be sure and post pictures of what you find, and go ahead and take pics of the repair procedure.
glad I could help with the diagnosis.

Actually, I checked that line last night and it is not black but a greenish yellow. I'll take a picture, which I'm going to post shortly. Also, I looked at pictures taken last year, in order to compare the vac line color: it is exactly the same as it was LONG before this issue came up. So, does this confirm that the cause is NOT a damaged diaphgram after all?

Thanks...

Quote:

Originally Posted by kerry edwards

If there's oil in the line, I'd order both the diaphragm and check valves. No reason not to replace the check valves while you have it open.
Takes an hour or so to rebuild it.

Please see what I reported in the answer above... The vac line is NOT black, but exactly the same color as it has always been. However, I have to say that there has been a tiny amount of oil at the vac line connection with the air filter since I bought the car over two years ago...

When you say it takes an hour... do you mean you can work on the pump without removing the radiator?

Thanks...

Quote:

Originally Posted by slarson80

Just because I did not change my check valves does not mean you should not. My case was much less severe, if I had oil dripping from my air cleaner. I would have changed mine too. OK probably should have anyway, but so far, so good....

OK.

Thanks...

Quote:

Originally Posted by cdplayer

This happened to me too with my first Mercedes. A 300CD. Turns out the vacuum pump diaphram wore out, and was letting oil pass through it. Then the oil was being pumped into the air breather, and into the vacuum lines inside the car. What a mess to clean up. I think I had to dismantle four of the dashpots inside the car to clean the oil out. After that all my vacuum thingys worked again.

In my case, the vacuum system hasn't worked (for instance, no automatic door locking) since I bought the car over two years ago... In my case a tremendous amount of oil ends up on the ground (through the tiny holes at the base of the air filter housing) even after a short drive.

Someone mentioned that a vac line turning black points to a faulty diaphgram... However, that's not so in my case (it is greenish yellow, the same as it always has been). So, the question for me now is, is it still the pump diaphgram that I need to look into at this point?

Quote:

Originally Posted by Stevo

When you replace the small bolt in the center of the new diaphragm DONT OVER TIGHTEN IT. It doesn't take much torque.

OK.

Thanks...

kerry · #25 06-13-2007, 12:13 PM

No need to remove the radiator, just the fan.

Given the clear vacuum hose I would engage in more diagnostics. Take the vent hose that goes from the valve cover to the air filter and stick it into a plastic bottle and drive for a while. See how much oil it is putting out and whether there is still oil dripping from under the air filter. This will tell you if the oil is coming from the crankcase ventilation hose or being pushed back up the drain tube.

rino · #26 06-13-2007, 01:06 PM

Here's a current picture of the vac line:

Suddenly leaking a lot of oil from air filter housing - Help!!!-vac_line.jpg

As I stated above, the color is identical to what it has always been for the time I've own the car. Again, there has always been a few drops of engine oil when disconnecting the vac line from the connection on top of the air filter housing.

rino · #27 06-13-2007, 01:12 PM

Quote:

Originally Posted by kerry edwards

No need to remove the radiator, just the fan.

Thank God...

Quote:

Given the clear vacuum hose I would engage in more diagnostics. Take the vent hose that goes from the valve cover to the air filter and stick it into a plastic bottle and drive for a while. See how much oil it is putting out and whether there is still oil dripping from under the air filter. This will tell you if the oil is coming from the crankcase ventilation hose or being pushed back up the drain tube.

I have to say that the vent hose in the case of my car ('79 240D) does NOT go to the air filter, but to a connection below it to the manifold intake... Given that, does it make sense that I do the above test you are suggesting?

Thanks...