Big oil leak from LEFT side of engine - near alternator
 

I JUST got a new crankshaft seal and spacer ring put on my 83 300SD, after another attempt that seemed to lead to still major leakage. I am starting to think that this point that it's NOT the crankseal anymore (or maybe never was).

The pattern of where the oil is dropping seems to be directly around the alternator, where the lower half of the engine seals against the main block. I had the car sit for 10 minutes running and the oil was definitely dripping on the left side of the engine, and NEVER from the front. I know from the crankseal leaking, it at least would drip directly DOWN when at idle. I know that any oil leak while driving down the highway will make a mess on the whole underside, so I'm talking about when the car is parked at idle.

I was curious what the heck was there to possibly cause this? It's not near the turbocharger from what I can tell - this is coming in FRONT and underneath of that, right where the alternator mounts.

Is there something obvious?

I will look through the FSM and see if there is any pictures of engine disassembly to help pinpoint the possible location before tomorrow actually doing the disassembly.

It doesn't look like it's the oil pan tube - since it's higher and closer to the front.

My first guess is the upper oil pan gasket, somewhere it being worn away, leaving a big gap. I will start taking stuff apart in the morning to see.

I do know that doing the crankseal (and spacer ring) twice has done nothing to even LESSEN the leak.

If it appears to be the upper oil pan gasket, can that be dealt with silicone sealant instead of replacing the whole rubber gasket (ie removing the engine)?

Or almost like it's something between the alternator and the EGR. Once the oil is warm, it drips pretty bad. But it's quite centralized, which makes me hesitate that it's an entire large gasket (upper oil pan). With a gasket failing, I'd think it'd leak from more than just one tiny spot around the alternator.

Chain tensioner?

Sixto
87 300D

If you know the general area of leakage, degrease it well and when ready, document the leak when you've found it by running the car 10 mins to simulate the previous observation. The cleaner engine should allow you to determine the source/s of the leak.

The only part I can think of, in front and below the turbocharger, is the wastegate hose, or the large U-tube.

Just to be clear, you say this is on the left side, when facing the engine. From the car's point of view it's the right side.

I'm guessing he has live theater experience rather than dyslexia and didn't move the alternator :)

Sixto
87 300D

BTW, there is only a gasket between the aluminum upper oil pan and the iron sump. There isn't a preformed gasket between the block and aluminum oil pan. There's a specific sealant that MB shops use though a number of sealants should do an adequate job. There's no way around separating the pan from the block and thoroughly cleaning both surfaces, though.

As MBeige suggests, thoroughly clean the engine rather than take it apart. Have it pressure washed or even steam cleaned then watch it daily/hourly/in real time as necessary to find the source. If you take it apart now, you'll have a lot of dirty parts and possibly insufficient forensic ability to find the source.

Sixto
87 300D

If he didn't say "near alternator" I would have said oil pressure lines! :eek:

There is the turbo oil feel line atop the turbo.

Sixto
87 300D

If it is right at the front of the engine, on the left as you are standing in front of it, I reckon it could be the chain tensioner as mentioned earlier - another place worth checking out though is the top cover gasket. These are meant to be a fit only once items but they tend to get refitted and refitted and refitted (from what I've read) though.

Could be radiology experience. That's my wife's excuse, anyway. X-rays evidently get hung with the left side on the right.

What I don't understand, though, is how "left" becomes "right" when you open the hood, but the front doesn't become the rear. If the alternator moves to the left, shouldn't the headlights move to the rear?

Degrease thoroughly as mentioned then put in a fluorescent tracer in the oil and examine the general areas with a black light after brief intervals of running the engine. The glowing will be easier to see and trace. You can buy the tracers at a good auto supply store.

The PO did not exactly do this but I think it is acceptable to say something is to the left or right of something as long as you say what position you are viewing from.

Even though you are supposed to decide right or left as if you are sitting in the Drivers Seat; ask a bunch of People which side of the Car their Battery is on.
I am going to guess 50% of the time People are going to reference that from a view Standing in Front of the Radiator (if the Radiator is in the Front) looking towards the rear of the Car.
I think it is because they see the Battery that way when the Open the Hood.

X2