oil out my dipstick

[ododge]

Just purchased an 82 300D turbo. I changed the oil and drove it for 60 miles on the highway checked the oil level, added 1/2 a quart and drove home. three miles from home the oil pressure began to plummet. I stopped and looked under the hood, oil on the hood above the not completely seated dip stick and lots of oil all over drivers side of the engine. took four quarts to get back me back on the dipstick and home. Today I hooked a hose to the dipstick tube and over to a plastic container and sure enough in 20 minutes the car pumped 1/2 a quart of oil into the container! Is there a breather that could be clogged or have I just get excessive blow by? fyi I tried the same hose on the breather nipple on the valve cover and got some oily residue in 1/2 an hour of driving but no liquid oil. Any thoughts?

[kerry]

If you search on it, there are a number of threads on this topic. Could be you have an excessive pressure problem or, it could be that you simply did not seal the dipstick into the tube after checking it while changing the oil.

[jt20]

I don't know if this has been covered in the threads that Kerry is alluding to...

But make sure to inspect the breather cover on the inside of the valve cover. It may be a legitimate culprit in the 'clogged PCV system' theory

If it is not sludged up, try removing the the breather hose on the VC and replace it w/ a short length of tube. If your car doesn't puke, then perhaps the blockage is in your oil seperator / air filter etc..

the last thing I can think of is incorrect oil level. Next time you change the oil, measure the amount you put in. Record where it sits on your dipstick.

[SD Blue]

I believe your first suspicion of a clogged breather hose must be the problem. Nothing else will build that kind of pressure, that I can think of. Too much blow-by is very doubtful as I would think the engine wouldn't even start if it was that extreme.

Originally Posted by SD Blue

Too much blow-by is very doubtful as I would think the engine wouldn't even start if it was that extreme.

Thats not possible. A few PSI in the crankcase would blow out all the seals long before it could possibly stop the engine from rotating.

There is a rubber o-ring on the dipstick that usually gets ignored, replace it first and see if the problem repeats.

[Shorebilly]

The Vacuum Pump pulls from the entire vacuum system.....Power Brakes, ignition shutdown, door locks, and AC/Heat valves...and then some.....the Vacuum Pump discharges into the crankcase......so if you have a large vacuum leak....or maybe several small ones......you could be pumping air directly into your crankcase......

I believe that the engine should run under a slight positive pressure....so that "O" ring on the dipstick, is important as well......

SB

[Rocketrider]

I replaced my breather hose on the w126 with a new one that someone gave me. The engine wouldn't run with it on, but ran fine with it off. I ran a piece of wire through the hose and found that it was clogged by mud dobbers. I don't think it's a clogged breather hose, but that's easy enough to check for. If your oil level is low, I would take the top off the oil separator and add oil there to see if it makes its way down to the crankcase. If not, then you have a clogged separator or return.

Originally Posted by SD Blue

I believe your first suspicion of a clogged breather hose must be the problem. Nothing else will build that kind of pressure, that I can think of. Too much blow-by is very doubtful as I would think the engine wouldn't even start if it was that extreme.

[ododge]

My breather hose was not constricted and the oil return in the air cleaner was not overly caked up with grunge. so I'm liking the vacuum pump idea I need to go through that system anyway. However I will never again let the dipstick be anything but well seated with a good o ring.

[pawoSD]

The dead motor we pulled from my dad's SD (had 313k on it) died belching oil out the dipstick....it still ran, but leaked oil and burned oil all over the place. (huge clouds) Haven't opened it up for a look yet....oh, and it had about 20hp or so, it could barely get up the driveway with the pedal to the floor!

New motor is awesome though. Its got some sick power!!! It will pull past 90-100 with EASE.

It was a factory MB replacement (into a car with 161k on it when it was pulled) (we cleaned it up and found the factory rebuild tag on the block), so it probably has less than 90k on it. Amazing. Paid $550 for it!!!

[Beagle]

Crankcase pressure should be neutral at idle and negative above 1000rpm in a healthy engine. Pressure between the turbocharger and air filter is always negative and more than sufficient to scavenge normal blow-by from the crankcase.

A simple test is to remove oil filler cap and seal a thin piece of pollythene sheet over it with grease. At idle it should not blow off and as rpm is increased to about 2000rpm should suck into the cover slightly. If blow-by is sufficient to lift off a loose filler cap it's time for a rebuild!

A word of caution!Never block the breather with your finger (or anything else) while the engine is running. While this should cut the fuel in +/- 10 secs,if it fails to do so you will distort or even burst the valve cover.

[jt20]

Originally Posted by Beagle

A word of caution!Never block the breather with your finger (or anything else) while the engine is running. While this should cut the fuel in +/- 10 secs,if it fails to do so you will distort or even burst the valve cover.

2 things.

you are saying the force exerted by your hand on the VC will be greater than the pressure required to BLOW APART the cast aluminum valve cover. And, that the VC has the weakest seal on the engine. I find both of these very difficult to believe, please explain.

2nd- do you think that the absence of a postive crankcase ventilation system would cause harm to an engine? Lets say the the crankcase pressure only had to overcome atmospheric pressure at all times.

[t walgamuth]

Originally Posted by ForcedInduction

Thats not possible. A few PSI in the crankcase would blow out all the seals long before it could possibly stop the engine from rotating.

There is a rubber o-ring on the dipstick that usually gets ignored, replace it first and see if the problem repeats.

I am thinking he meant it would lack sufficient compression to start, not be actually locked up.

[Beagle]

Originally Posted by jt20

2 things.

you are saying the force exerted by your hand on the VC will be greater than the pressure required to BLOW APART the cast aluminum valve cover. And, that the VC has the weakest seal on the engine. I find both of these very difficult to believe, please explain.

Correct and the answer is in the theory of hydraulics. Let us assume you hold your thumb over the valve cover vent pipe sealing the crankcase and the pressure fails to move the pump shutoff diaphragm cutting the fuel. Let us also assume that the pressure rises to 10 psi.(as it would quickly with high blow-by). The area of the breather pipe is approx 1/2 square inch – i.e. a force of 5 lbs on your thumb. The area of the VC is approx 25in x 6in = 150 in² x 10 psi. A vertical force of 1,500lbs on this 3mm aluminum casting held down with 4 screws and this same pressure is pushing horizontally on the sides of the cover. We have the same story down below on the crankcase.

Originally Posted by jt20

2nd- do you think that the absence of a postive crankcase ventilation system would cause harm to an engine? Lets say the the crankcase pressure only had to overcome atmospheric pressure at all times.

If your breather were to be left open to atmos. you would always have positive pressure in the crankcase as blow-by is now being pushed out instead of being sucked out. Vacuum between T/C and filter is 4 to 5 inches at 3000rpm and increases with rpm – it’s not insignificant! Blow-by reaches a maximum under high load/high rpm. Crankcase pressure is undesirable, causes leaking F/E and R/E oil seals and in extreme cases as the subject of this thread can blow oil out of dipstick. My own 300D with 465k miles on original engine still passes the test I describe in a post above.

High blow-by, indicated by positive crankcase pressure, poor compression and high oil consumption that all go hand in hand is really decision time.

Realistically you have 3 options:

1) Sell now as a runner for what you can get if the car is not worth a rebuild.
2) Run it into the ground and sell to a junkyard.
3) If the car is worth a rebuild and you intend to keep for the long term, say 5 years or more, rebuild sooner rather than later. The longer you leave it the more it will cost and you may as well have the benefit of the new engine now rather than in a year or two.

Have a nice day

Originally Posted by Beagle

If blow-by is sufficient to lift off a loose filler cap it's time for a rebuild!

That would be a total waste of money to rebuild a good engine based on minor blowby.

2nd- do you think that the absence of a positive crankcase ventilation system would cause harm to an engine? Lets say the the crankcase pressure only had to overcome atmospheric pressure at all times.

Not at all. The CCV system is for emissions control only (to burn leftover hydrocarbons and oil vapor), almost all modern diesel engines in semi's and off-road vent their CC gases straight to the atmosphere and have done so for decades.

Vacuum between T/C and filter is 4 to 5 inches at 3000rpm and increases with rpm

If you have that much vacuum then your air filter is dirty or too restrictive.

Crankcase pressure is undesirable, causes leaking F/E and R/E oil seals and in extreme cases as the subject of this thread can blow oil out of dipstick.

If you have enough positive pressure to blow out those seals, they were either LONG overdue to be replaced or the breather is severely restricted.

[pawoSD]

Rebuild an engine because of blowby? Yeah right! My engine has had a significant amount since I bought it. 70k later, it still runs great and starts right up in the cold.....I say no to rebuilding!