Oil and fuel under injector pump
 

Good Evening,

I just finished putting an oil pan gasket on my 1984 190d (W201) and was letting her run to check for leaks. I noticed diesel mixed with oil dripping down on the floor. I immediately looked on top to see what was the matter. I could see a mixture of oil and fuel seeping out on the bottom of the fuel injector pump. This don't look good. Anybody got any ideas as to what happen and how much will this cost me? Thank you.

Merry Christmas,

Hugh Sr

I would clean everthing off good degrease it with Brake Cleaner to get it dry and isolate exactly where the leak is coming from.

If it was on my 84 300D the only places Fuel could get into the Oil would be past the seals on the Fuel Supply/Lift Pump (in my case this is a single tiny O-ring) and past the Elements inside of the Fuel Injection Pump (due to wear in the Plungers and Barrels or if the Elements some how got loose).
All of the above leaks would be internal and would leak Fuel into the crankcase Oil and would not cause an external Fuel leak.

Do not know much about your vehicle but I believe you have a Fuel Thermostat; the have been know to leak as well as the Delivery Valve O-rings (Fuel Pipes) on the Fuel Injection Pump. Those could cause external Fuel Leaks.

On your type of Fuel Injection Pump lower Pan Seal and the Throttle Arm seal have been known to cause external Oil leaks.

Diesel is right. You need everything clean to find the leak. My guess is you have a diesel leak that is dissolving some crud & oil and then dripping down.

Oil and fuel under injector pump
 

Diesel|911

Where would the lower pan and throttle arm seal be located? I appreciate the help - repair costs kept me awake nearly all night. Is this a job I can do, it took me two days to do the oil pan gasket (my injector pump was fine before I did this). Let me tell you how I did it. I took all the things loose to lift the engine up with a lifter. When I got all the bolts out & let the oil pan drop I ran my fingers along the top edge of the pan. There was not a gasket. I got a mirror to look at the top to make sure - no gasket. Knowing this I thought about all the other things I would need to do to get the pan off, such as; remove the oil pump & and lower the sway bar. Since the gasket was made of some type of rubber material I decided to slip one corner under the oil pump and that would allow me to just pull the rest of the gasket on top of the pan. That worked. I aligned the holes up, put the bolts back in, and torqued most bolts to 10-15 nm & the larger ones to 25 nm. I thought someone else might use this info. Thanks.

Merry Christmas

Hugh Sr

I believe you use some sort of Sealant insted of a Gasket. I think it is the same for my larger Aluminum Oil Pan.
As far as the leak go as I said you need to be 100% sure where the leaks are before you start taking things apart.
The Throttle Shaft Seal is just an O-ring; it might be round or a square one depending on the Fuel Injection Pump.
The Bottom Pan has a big square O-ring. On mine it is held up by 6 screws but I have never seen your Engine so I do not know how much room you have under the Fuel Injection Pump to work.
You will need to get a Mirror and take a look.

Actuall I find it hard to believe that the Fuel Injection Pump would Leak both Oil and Fuel at the same time. This makes me think the leak is else were or you for some reason have more than one leak.

Oil and fule under injector pump
 

Thanks Diesel|911

It looks like the fuel is leaking on the side of the pump that attaches (front of pump) to something - I don't know what its called. It is leaking where they meet. I put my finger on the fuel coming out and it seems just a little thick, something close to maybe new oil. I guess this means that the pump will need to be pulled to fix my problem - or, maybe if I try to tighten up the bolts this will do it. Could lifting up the engine have caused this problem. It wasn't doing this before I lifted it up to take off the oil pan? Thanks.

Merry Christmas,

Hugh Sr

I cannot tell from your description exactly where your leak is. If your Fuel Lines are those hard plastic ones it could be one of them cracked.

I lifted and Engine ounce and ruined a Clutch because part of it got caught on something that was out of sight to me. I was jacking up the Engine Crane and that thing was caught. So it may be your problem is caused by moving the Engine and maybe not.

It would be nice if you could take a pic of the leaking part.
If you send the Fuel Injection Pump to a shop you are talking maybe $1200 or so to fix it.

Oil and fuel under injector pump
 

Thank ya again Diesel|911

I'll try to pick up a camera tomorrow. This has not affect on the engine running - she runs like silk at low and high rpm's.

Merry Christmas,

Hugh Sr