The other night I was tinkering around with the engine and I noticed oil in the inlet of the turbocharger. The hose that comes down from the valve cover intersects with other hoses from the vacuum pump. While the engine was running I momentarily disconnected the hose from the vavle cover and blocked off the pipe. Within 3 to 4 seconds the engine almost died. Is this normal or is this too much. I am starting to question the 75K that is on this car.

PeterG


79 300SD 75K
96 Chrysler Concorde 120K
69 Shelby GT Conv 54K
89 Jeep 180K

With the engine running, take off the oil cap. Normally you should see a little smoke coming out, that is normal. But if there is alot of smoke and dropletts of oil shooting out, then you have excessive blowby.

Hi Bill,

I had a question regarding the correlation between blocking off the valve cover pipe and the engine cutting off. Why is it that the engine does cut off when this is done? Does pressure build up somewhere causing that to happen and if so where?

Also, what are the time parameters of what is a sign for a good engine versus bad when you do block off the valve cover pipe. For example, if the engine dies in XXX seconds it is good. IF it dies in YYY seconds it may be bad.

Herb
'87 300SDL
'82 240D

I have a 87 300TD with 202K miles. I blocked the vent line from the valve cover to the air intake. With the car still running at 20 seconds, I stopped the test. I did not notice any back pressure on my thumb. I would assume that the crank case gets pressurized to positive pressure and backs up into the piston chamber through leaky rings and in essence starves the engine from nice clean oxygen rich air. It would be interesting to see a comparison between a compression test and the "thumb test". Not very technical but the thumb works the best.
Henry

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63 190d (sold)
69 220D (sold)
69 280SL (sold)
76 BMW 2002 (sold)
86 190E-16v (Demised at Laguna Seca Turn 9)
87 300SDL (sold)
87 300SDL 135k
87 300TD 280k (sold)
95 E320W 211k
95 E320w 111k
05 C320 4matic
06 E320 CDI 90k (Totaled by a texting 19 year old girl in a nissan)
2013 GLK 250 Bluetek 4MATIC

How much does altitude affect this test? I live in Denver at 5000ft. My 77 300d has 56k on it and shut down at 5 seconds when cold. Can anyone do the math to translate this into an equivavlent at sea level?

My '85 300cd with 175,000 miles shut down in 8.5 seconds via the vent blocking test. Outside temp 71 f, 480 ft above sea level at full operating temp. I use very little oil between changes and change every 5k and I use 20/50 castrol.

I purchased this car as a daily driver because I was commuting between San Diego and Los Angeles once a week two years ago. I now wish I had purchased one new.

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1990 420SEL
1995 E320 Coupe
2000 SL500
2009 ML320