Pressure from Top Cover - Blow by or blockage ?

[mistral]

Looking at buying an L400 with 4M40 motor with 200k on it and picked up significant blowing when I hold my hand over the oil filler hole with the cap off and engine idling. A fair amount of oil spatters out too. No significant oil in the intercooler and none in the air filter. No smoke from the rear. The owner claims it uses little or no oil between changes. What are the chances that this is due to blow-by, or simply a blocked vent/screen ?
Anything that helps me make an informed decision greatly appreciated.

[Krazyistkarl]

there's a lot of discussion about this around the web, most people say it's quite normal for these engines. Mine does the exact same thing, and as of lately its forcing oil out from the filler cap as well. I have tried cleaning the filter under the valve cover once before, this time I'll be drilling the rivets out to actually get at the screen.

browse through this thread
http://www2.pajeroclub.com.au/forum/sho ... hp?t=19999

[mistral]

Thanks for the feedback, very helpful.

[Krazyistkarl]

I bent the tabs on my oil cap to make a tighter seal, I more oil coming out from the filler car.