I was wondering where this happens?

I know the process, for the most part

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Ol' Turbo: 1985 300D 182k: Very slight dancing, possibly from engine vibration. Smokes a bit when you remove it and a very small amount of oil escapes initially as well.

Ol Norm: 1980 300TD 232k: Dances a bit more, still not violent, but motor mounts are also a bit haggard. A bit more smoke with cap off, and some oil drops sneak out.


Perhaps this has been mentioned before, but wouldn't the weight difference of the plastic vs. metal cap create another variable for this test. Ol' Turbo has plastic and Norm has metal.

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1985 500SL Euro w/ AMG bits 130k
1984 300SD Turbodiesel 192k
1980 240D Stick China 188k
2001 CLK55 AMG 101k
2007 S600 Biturbo 149k Overheated Project, IT'S ALIVE!!!

I did this test the other day with my 240D for the first time on any of the three old diesels that I have owned. The cap would dance for a bit and then float off if I would let it (didn't want to have to go under the car to retrieve it, so I kept pushing it back down). Also, oil droplets were spraying around a fair amount - had to wipe some off the bumper.

The engine was only running for a couple minutes when I tried it.

I suppose that means I probably have alot of blowby, but it still starts fine and drives smooth... it does consume some oil, but I'll worry about it some other time, like after the clutch is working again

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I wonder how much this really say's about how much life is left in your engine? There are a lot of variables.

I've done this test with 20w-50 with no oil droplets escaping. With 0w-30 oil splatters about halfway across the engine bay.

Big difference in weight between the metal & plastic caps, as mentioned.

After driving my car a few weeks ago, I did the blowby test, and concluded my car had moderate blowby at normal operating temperature. Then I checked my air cleaner and discovered the filter was still clean. I also didn't see any evidence of oil getting sucked down the throat of my intake. So now I'm wondering if my crankcase ventilation is functioning normally.

Back in the olden days I had a VW Rabbit that ran away on me when it had 150k miles on it. Blowby was bad enough that oil was making the full "round trip", back down into the engine through the air intake. I thought my engine was toast! The VW dealer installed an improved style blowby tube that routed the oil back into the crankcase. The timing belt had also jumped 2 cogs during the event.

That engine was still running well at 340k miles, and I know it still ran up to 380k miles, with my sister driving (and neglecting) it.

My sister got rear ended on the freeway, which is what finally took that car off the road. In general, Rabbit diesels are not supposed to be as durable as Mercedes, but that's a lot of miles with moderate to severe blowby. I changed my oil religiously @ between 2k and 3500 miles. (I judged it by driving conditions, and smell.) I also drove the heck out of it.

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1979 240D, 4spd manual, Power Sunroof, manual windows, 147k miles, Pastel gray/Black MB Tex.
1991 300D 2.5 - Smokes like it's on Crack!

1980 240D - 182,000

runs strong, but the cap FLIES off and covers me with oil drops...

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http://i106.photobucket.com/albums/m...73378_30-1.jpg

Did anybody see where my oil cap went?

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Remember, Safety Third!
'99 E300 Turbodiesel, '82 300TD, 1996 12V Cummins Turbo, '94 Neoplan - Detroit 6V92TA

162K and very little blowby. The air cleaner housing got oil soaked where the vent tube grommet is but I think that is because the IP mechanic overfilled the oil.