by the loosened oil filler cap method i have a steady dancing on the crankcase, doesn't blow off or anything. so today i decided to pull the vent hose and plug the hole to time how long it would take to die. i hear 1-5 seconds is bad, 5-10 is good, and anything over 10 is very good. well, either i have totally missed a step in the process or something isn't right because my car never did die...i let it go 30 seconds twice in a row at which point i got nervous about the pressure build up and removed my thumb. there was an initial burst of gases (which tells me the pressure was building) while the crankcase equalized and then back to normal.

so while the optimist in me would love to take this as a sign that i have millions of miles left on my engine, it is much more likely that i screwed up or that something else is going on. from what i understand, the pressure acts on the fuel diaphragm when it builds up enough and cuts the flow thereby stalling the engine, so i guess there could be a few points of failure, but i would like to know what you guys think.

1983 300d with 196k-ish otherwise runs smoothly - valves done recently, rotella 15w40, etc. the engine was operating temp (85c) when i tried it. if the best answer is "shut up and just drive it" then i'm cool with that, but i need to hear it from someone else (besides my wife of course ).

thanks!

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1983 300D classic white 196,xxx
2007 toyota yaris lb
2007 nissan versa (wife's)
2001 nissan frontier
2006 bmw r1150gs
2001 ducati monster 900
2003 zr7s
2007 klr650

It's not a reliable test because a leaky gasket somewhere will let the gasses escape. In addition, it could blow a gasket. Shut up and drive it. I'm not your wife.

At one time we had an experiment going on a thread where a (30gallon?)garbage bag was attached to the vent hose and the number of seconds it took to fill was recorded. You may be able to find some data on that thread and do some comparisons.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Plugging the CCV hose is a very BAD test and does more harm (blowing out oil seals) than it tells you about engine health.

The CCV hose should never be plugged with the engine running.