My car just developed a huge oil leak over the last day or two. I saw a small puddle under the car about the size of an orange from where it sat over the weekend. I can run it and it will leak a half dollar size in about 5 minutes. Its very black and is coming from the very rear of the engine pretty much in the middle. Will an oil filter housing drop in the same place? I have already washed the engine as best as I can and I will be monitoring. I did searches and found some good info but I am wondering who that had leaks of this size found them to be rear mains or oil filter housings or other. By the way, its an 84 300D with 238,XXX miles. Thanks again, Eric.

1984 300d Turbo 136k
Check The Valve Cover Rear Gasket Install New One And Check Valves Same Time 10 Mm Intake And 35 Mm Exh. Turbo Engine Cold

The SD has been leaking oil from the back of the engine on the passenger side. This is after my complete rebuild of the head, oil cooler lines, oil filter housing gasket, and valve cover gasket.

I had pulled the valve cover today to check the valves at 1000 miles. Returned the cover to the head and decided to properly torque the four nuts to 11 ft-lb. Lo and behold, my kentucky torque was far less than the specification. Surprising how tight 11 ft.-lb. is when you are trying to deliberately be gentle and not overtorque them.

Them's some mighty loose valves......

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Palangi

2004 C240 Wagon 203.261 Baby Benz
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Could be valve cover, oil filter housing, rear main or valve cover gasket. Oil filter housing gasket tends to leak down just forward of the bellhousing on the side of the oil pan unless you're moving forward. I think there are also a couple of oil gallery plugs at the back of the block.
Clean it at the car wash, then use an extension mirror to look at the back of the block to see how high up the oil is coming from.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I'm in the same boat, floating in a sea of oil... I replaced the oil filter housing gaskets and valve cover gasket and that lasted about 3 days. Now I have about the same leak you described, with oil seeming to come from in between the engine and transmission. Oil is in face coming from the top of the engine somewhere around the back, but I can't locate it...

I'm going to re-mount the valve cover with gasket maker in addition to the rubber gasket I just replaced. There is oil seeping out all around the gasket even though it's brand new.

I bought a head gasket kit but I'm dreading the job. Anything else that can leak around the back of the head?

-Colin

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1981 240D
3.0L Turbo Swap, 4-spd
100% WVO hot filtered, under pressure, without filter bags. All those things that "can't be done".

i hope you not talking about a gasket sealer

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As mentioned above, I'd suggest you properly torque the nuts to 11 ft.-lb. My suspicion is that the problem is either overtightening or undertightening. Both will give leaks with only four mounting points.

Yes, the head gasket can leak out the rear & make you think it is the rear main. It happened to me. Upon pulling the engine, I thought it was that bracket that holds the turbo oil supply line at the back of the head, & that it gouged through the line-not so. Paul central FL

'84 300CD 290,000

I washed off the back of the engine specifically and the whole top of the trans bellhousing and the rear sides of the engine so I can see if it is originating from up top. After my 37 mile 80 MPH drive in to work I popped the hood and it was dry up top. I also looked at my air filter oil separator last night and it looks good so as not to allow crankcase pressure buildup and subsequent oil leaks everywhere. I will still be monitoring. If it is a rear main, my attitude has moved from complete horror to actually wanting to tackle the job as long as I have a place to do it. I don't have the room at home nor do I want the mess. Does anyone rent out stalls with lifts anymore? That would be the best. Thanks everyone so far. Eric.

Are you aware that the crankshaft has to be dropped to replace the top half of the rear main seal? I'd investigate the possibility of replacing just the bottom half. I think there's a greater than 50% chance that rear main seals leak thru the bottom half since gravity pulls the top half down to the crank.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

bearings hold the crank in place not the seal.....that gravity effect will only apply within the range to tolerance in the bearings

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Proud owner of ....
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1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Yes, but gravity is still acting to either pull the seal down onto the crank or to compress the seal downwards away from the crank.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Yes, I know about the crank having to come out. I am a little apprehensive about tackling a job this big without a lift but I may still. I did start to think about it, though, I don't think these engines are too bad to pull with the trans attached. There are a few bolts underneath for the crossmember and driveshaft and then the exhaust pipe and motor mounts but most of the other stuff can be gotten from the top, right? I have pulled and gone through many engines but it was all when I was all at a Chrysler/Jeep dealer and had my lift and shop equipment at my disposal. Can a rental engine hoist lift the engine and trans together? Does the radiator support come out or can the engine/trans be tilted enough to easily get it out? I guess the factory had to get it in at some point.

all youd probably need is max a 2 ton engine hoist. i have access to one if i need to ever pull my engine.. i too am worried if my rear main is leaking but others have said it probably isnt it could just be the valve cover gasket which highly suspect