Diesel RVs: [diesel_mercedes] HUGE oil leak, part 3

It's been a busy couple of weeks in LALA land. Court fights on big cases and all the prep that goes into them. So I've been driving the Caddy hearse and letting the 300SD sit in the garage. (At 12.5 mpg on the Caddy, I figure that this is a Christmas present into Nate's oil stock dividend checks.)

Finally, yesterday morning, I got back to it. I do not believe in coincidences - they work fine for movies and novels, but not often in real life. In my first message, I mentioned that the oil came spewing out in the days after a valve adjustment. So I went back and looked more carefully, now that any lingering oil has had a chance to drain off the engine.

Although the top and sides of the engine are relatively clean, the back edge of the valve cover gasket was PERFECTLY clean and shiny. That didn't strike me as a particularly good thing. The more I looked, the more it looked as if the gasket wasn't uniform across the back of the valve cover.

So I got a new gasket and this morning I went at it. You have probably read my descriptions of how Nate does a valve adjust in 30-45 minutes, including the time to put on his coveralls and get out his tools. I started before 10:00 a.m. and finished after noon. And that's without wasting any time adjusting the valves.

The cover came off easily. The only issue was how few of the throttle and cruise control linkage rods I could take off (to avoid confusion on reassembly). It turns out that I missed one, and got the cover halfway lifted before its vertical travel stopped.

Indeed, the gasket was folded over under the back cover edge, allowing oil a low resistance escape point. The gasket didn't look damaged. But I used the new one anyway. The new one was not as stiff, and seemed to grip the cover edge tighter. Of course, it hasn't spent months sitting in hot oil.

The valve cover had been resistant to coming off, even with the old gasket loose. Putting it back on again with the new gasket was impossible. There must be some trick, short of moving the cruise control actuator. But I couldn't figure it out.

Eventually, I got the gasket on (that's easy), then the valve cover (that's not easy) and then got the gasket onto the bottom edge of the valve cover (least easy of all). After that, everything buttoned up neatly. I sprayed some white lithium grease into each of the little linkage balls before reassembling (I hope that wasn't a bad thing).

No matter how I looked, I couldn't see any problem with the gasket. So I poured three quarts of Mobil 1 into it.

The process also involves pulling off the air cleaner housing. When I did that, I found the normal two (2) broken rubber isolators. Happily, I had some junkyard spares in the trunk. It turns out that there are two different heights for these things. I had had a mixture of heights in place. I was able to replace all three with the tall height ones.

Does anyone know whether an '81SD is supposed to have tall or short isolators?

I wonder whether mixing the short and tall increases the inevitability of them failing?

I used the round ones. I have heard that the hexagonals are better - more durable - but I haven't seen them available in a while. Does anyone know whether they really are better, and, if so, where to get them?

Everything fit back together and I proudly put the tool box back in the trunk. After the trunk was locked, and I had peeled off the rubber gloves, I remembered the oil drain tube from the back of the air cleaner. Of course, when I checked, the tube on the air cleaner housing was no where near the tube going back to the engine.

Another half hour of fun and games fixed that.

Then the big test drive. first to the post office. Got there to find that I had carefully left the post office box key in the Caddy. BUT, no oil showing on the post office parking lot. Then to the grocery store. Again, no oil showing.

I'm too scared to open the hood and actually look at the gasket. Maybe tomorrow morning. But for now it doesn't seem to be leaking.

My final analysis is that the oil was gushing out of the back of the engine, onto the tranny housing, and then flowing down onto the drive shaft, where it flowed along the length of the car and was spun all over the bottom of the car. Maybe it will inhibit rust.

The real test will be tomorrow evening. There's an Orange County Bar Christmas Party, which is more than an hour's drive. If the oil level stays good for that, then I think that we've got it fixed.

Tom

ps: Let's not tell Nate about this post. He'll just get all guilty feeling about the valve adjust and the gasket, and he really has enough on his plate with the back surgery coming up and stuff at the office. So let's let him not worry about this one.

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