Oil Leak location??

[Wallknight]

Hello all,
I've been hunting down the oil leak in my 82 300D (t) since I got her 6 months ago. Here is as close as I can get:

Oil leaks onto the top of the oil pan from a location near the front of the fuel pump. It is not the valve cover, nor a leaking tube. Nor is it diesel. 3 options seem possible.

1. leaking from a gasket around the hand pump.
2. leaking seal (if one exists) between the pump and the engine.
3. the 6 inch long oval/rectangular flexible pad on the underside of the fuel pump.

Anyone have any idea of where a gasket or something might be shot? I dont fully understand the dynamics of the fuel pump and oil lines around it.

Thanks,
Paul

Don't ignore the front crankshft seal. That one will throw oil around all over. Seems that it will leak oil out and then the oil will go up and land under the alternator, the udnerside of the IP, and also will slide back along the engine.
Good news is that this is an easier fix than it might appear, but can't tell from here if that is the problem.

[Wallknight]

No, whatever this is, it is located in this one very specific area. I've dumped many gallons of degreaser onto all to pinpoint this location!!

[sainttammany]

There is a gasket between the pump and the engine, however I have never seen one leak oil. I think it is just a thin paper gasket.Performance Products has an exploaded view on their site.

[Wallknight]

I'm guessing that to replace that would require removing the pump?
Paul

[sainttammany]

Yes it would, but I would be sure that is where the leak is. I replaced a pump using the Haynes manuel without any problems, but it was a time consuming job.

[240Joe]

wallknight.

I also just went through the process of finding all of the oil leaks in my 1983 300D. I now have it completely sealed, not one leak.

My leaks were from:

1. there are two plugs in the front of the engine near the bottom of the vacuum pump. These plugs cover pins that I believe hold tensioners for the timing chain. Both of the plugs were finger tight on my 83 with 130kmiles. At first, I thought it was the vacuum pump to block gasket, but in hindsight, I think all of the problem in this area was the loose plugs.

2. The turbo to oil pan tube grommet and oring. This leak was on the front of the engine but more toward the passenger side.

I've heard that the front seal rarely goes bad unless you get the engine dangerously low on oil, as the design is really good.

I had no leaks from the injection pump to engine. I would not jump into that job unless you a fairly sure. Try to get a light into the 7 oclock position of the vacuum pump near the two plugs.

The reason I think it might be these plugs is that after I found this problem on my 300D, I went over to my 1980 240d, which had a small leak (which I thought was a front seal), and found one of the plugs finger tight. I tightened it down, and now that car is now completely sealed.

Let me know if you need a better description.

thanks
Joe

[psfred]

I've seen oil leaking past the plug at the top of the oil pump drive (above and in front of the IP), but I don't know what is used on the turbo since it has a chain driven oil pump and there is no shaft up the the injection timer.

You could also have a leak at the chain retainer bolt (goes into the side of the chain case at the centerline of the injection timer) -- since it goes completely though the case, the threads can leak if not sealed with Permatex or similar sealant.

Also, is this really black engine oil or just fuel residue with dirt in it? Fuel residue looks like engine oil since most of the smell (and the more volatile fraction) is boiled off by engine heat. I've seen "oil" running down the sides of tractor engines from leaking injector seals.

Peter

[Wallknight]

Thank you for the replies!
First, it is not diesel. I've so thoroughly drenched the area in degreaser that there is nothing left to turn the diesel black, which it its.
Second, I wasnt aware of the plugs near the vaccuum pump. But arent those on the front of the engine? this is right in the middle.

Following saintamany's lead, I checked the tightness of the fuel pump bolt, and behold! they were all a good half turn loose (except for the one on top near between the engine and pump -- that took closer to 2 turns.)

So, here is the current status. It still leaks, but I dont know if it is from that location anymore. It is leaking at the valve cover gasket above the #1 injector. The stud that is right there was broken when I bought the car, and I've since replaced it with a bolt and 3 washers. Then I got a new gasket and have torqued the bolts as tight as I could. I"m thinking, should I let off the torque on the oposite side? Or, is my bot and washer fix killing me now?? (Oh, and it wasnt doing that last week when I was hunting for the other leak).

Hopefully I"ll have time tomorrow to get under there and do some more research!
Thanks again,
Paul

[lrg]

Be careful you don't overtighten the valve cover. The valve cover gasket is rubber and only meant to take a small amount of pressure or else the cover will cut through the gasket. You may want to remove the valve cover, check to be sure the gasket is not damaged, clean everything up and then reinstall but not so tight this time.

[Wallknight]

finally fixed this a few weeks ago. It was both the Ip gasket and the oil filter housing gasket. Heres some tips:

1. You'll need a 6mm allen head to get the filter stand off.
2. 24mm wrench for the oil cooler lines (probably need to grind it down to a narrower dimmension)
3. Mark the IP location so you dont have to re-do timing.
4. Allow lots of time. It took me all day, including the trips to the store for the tools.
5. reinstall the long middle bolt on the oil stand first. otherwise, there wont be room to get it back in later.

My problem was not a failure of the IP gasket; there was no trace of gasket material on it in the first place! Prior owner, it seems from other locations, did not believe in gaskets.

Leak free in 03!
Paul

[Aaron]

Actually, it is a 27mm needed for the oil cooler lines.

Did you put the O/F housing gasket on dry or did you use some RTV? As I have mentioned on this board before, I always use Wurth black RTV on those gaskets. Did you split the O/F housing and reseal the part that the pressure sender plugs into as well? Always a good idea.

Now, keep watch on your oil cooler lines for seepage. If they start to get bad, they can eventually burst causing all of your precious oil to pump out while underway, usually on the freeway.

[Wallknight]

Aaron,
the inner nut is a 24mm. I was able to get an adjustable on the 27. I put them on dry, and I'm not going to go back and redo it!

I know nothing about splitting the housing.

Aaron:

Could you please elaborate on:
1. Using RTV on the O/F housing seal. Both sides...?
2. "...split the O/F housing" - what does this mean?
3. What method do you use to "reseal the part that the pressure sender plugs into"? RTV or...?

Thanks-

[Aaron]

Paul,

24mm? News to me. Must be different on your car. You are referring to the oil cooler line connections right?? On every one of those jobs I've done, they've always both been 27mm fittings.

Moraine,

To answer your questions:

1. Yes, put RTV on both sides of the gasket that goes between the housing and the engine block. Don't put too much on there, just a light coating, especially if the gasket you have is paper rather than made of gasket material. As I said, I don't like Permatex products, so if you can hunt down a Wurth distributor, get some RTV from him. Or else you can use the black Mercedes-Benz RTV. Comes in a little white tube with a black plunger.

2. On "splitting the O/F housing"....When you take the housing off, you'll see the back part of it actually detaches from the rest of it by removing four 10mm bolts. It's kind of like a cover plate, once you have it off. But on the older cars, a 12mm oil pressure line threads into it and on the newer cars, an electric oil pressure sending unit threads into it. There is a gasket between this "cover plate" and the rest of the O/F housing which I would strongly recommend replacing while you have the housing off. Also if you have an electric oil pressure sender on your car, unscrew it (17mm if I remember right) and put a new copper seal on there, because if it's the original sending unit, the seal is probably leaking too.

3. On resealing this cover plate....As previously mentioned, get a new gasket and apply a light coating of RTV before mating the plate back to the housing (remember four 10mm bolts).

One thing I like to do when doing this job is to first wash the O/F housing in a solvent bath to get all of the caked on goo removed from the housing, then I throw the whole thing into an automotive parts steam cleaner. 1/2 hour later, it comes out looking BRAND NEW. So if you can find a shop who has a steam cleaner (most already have solvent tanks), ask them if you could put your housing in there for a 1/2 hour. Even offer some $$ if they seem reluctant. It will be well worth it. My $0.02