I have a 1980 300SD with 171,XXX on it, seems like alot of blow by is comeing out of the vent tube on top of the valve cover.

How much is too much?? Mine seems like a continous stream and if I hold my finger over the tube for a few seconds it builds quite a bit of pressure.

 

What is "Blow By"?

 

How much amount of smoke is tolerable without the use of measuring equipment? If anyone has the time, view the clips below and rate it.

1. http://www.youtube.com/watch?v=pYUsi0yUxH8
2. http://www.youtube.com/watch?v=DmvlFIW4CUY
3. http://www.youtube.com/watch?v=SZAGzRnJD0I
4. http://www.youtube.com/watch?v=ubWlNpokKTI&NR=1 (change engine?)
5. http://www.youtube.com/watch?v=iVzdNTw_Niw (perfect?)

 

The thing is the engine doesnt run too great, but I ordered a compression tester and I will check that before I decide what to do with it.