Engine oil from dipstick tube

[nyko46]

I post a thread a week ago about my Mercedes Benz 1982 300 SD having too much pressure build up in the crank case and having a lot of white smoke and after many replies to my thread I found out that the breathing tube from top of the valve cover to air cleaner was restricting that ventilation from engine. I had it fixed and even the smoke from engine that was an issue at that time is much better now. One thing still bothering me: If I plug half way (not completely) that vent tube I will have oil coming out from the dipstick tube. I check my oil level with cold engine and it is a little bid below the maximum but as soon I start my engine the oil level will show much higher than engine not running. As far I know oil level should show lower with engine running than with engine not running. I still trying to find out why it is happening. I will appreciated all comments from every one on this forum. Thanks for your help.

[Diesel911]

What is the Mileage on your Engine?
I would try doing the same test with the Oil Fill Cap removed and see if the Oil level is lower.
If the Oil level rises when you put the Oil Fill Cap back on I would guess you are still haveing an exccesive Crank Case Pressure Issue.

Try changing the O-ring up on the Dip Stick to a Tighter one to help decrease the chanc of a leak and hope for the best.

[Diesel911]

I have not read all of my FSM and have not noticed if they have a specific way to measure the Crankcase pressure with a Gauge or Manometer.
However, If you are having to much crankcase pressure and you are not going to fix the cause the next best thind to do would be to provide more ventilation.
Meaning create another additional vent hose setup or find a way to enlarge the present one.

[kerry]

I have a vague recollection of reading in the FSM how to measure crankcase pressure.

[leathermang]

Originally Posted by kerry

I have a vague recollection of reading in the FSM how to measure crankcase pressure.

Yes, MB has a special ( and you can bet expensive ) tool to measure this.
We had a very funny thread going about this a few years ago.. some suggested they would time the filling of large garbage bags and compare notes...

[oldsinner111]

Put new O ring from any Hardware store on dipstick.

[kerry]

Originally Posted by leathermang

Yes, MB has a special ( and you can bet expensive ) tool to measure this.
We had a very funny thread going about this a few years ago.. some suggested they would time the filling of large garbage bags and compare notes...

That process began. There's a thread with a video of a garbage bag being timed while it fills. I still think that's a reasonable means of comparison for rednecks like us.

[Cr from Texas]

Originally Posted by nyko46

I check my oil level with cold engine and it is a little bid below the maximum but as soon I start my engine the oil level will show much higher than engine not running. As far I know oil level should show lower with engine running than with engine not running. I still trying to find out why it is happening. I will appreciated all comments from every one on this forum. Thanks for your help.

Never heard of checking the oil dipstick with the engine running. I'd expect the turbulence in the oil pan would coat most of the lower end of the dipstick.

[Dee8go]

Originally Posted by Cr from Texas

Never heard of checking the oil dipstick with the engine running. I'd expect the turbulence in the oil pan would coat most of the lower end of the dipstick.

That's what I thought, too.

[SD Blue]

One thing I've noticed is that you need to pull, wipe the dipstick and reinsert for an accurate reading of the oil level after running.

[jkubica]

Originally Posted by nyko46

I post a thread a week ago about my Mercedes Benz 1982 300 SD having too much pressure build up in the crank case and having a lot of white smoke and after many replies to my thread I found out that the breathing tube from top of the valve cover to air cleaner was restricting that ventilation from engine. I had it fixed and even the smoke from engine that was an issue at that time is much better now. One thing still bothering me: If I plug half way (not completely) that vent tube I will have oil coming out from the dipstick tube. I check my oil level with cold engine and it is a little bid below the maximum but as soon I start my engine the oil level will show much higher than engine not running. As far I know oil level should show lower with engine running than with engine not running. I still trying to find out why it is happening. I will appreciated all comments from every one on this forum. Thanks for your help.

Hi
The idea is not to allow any pressure to build up in the crankcase - that's the purpose of having the breather hose on the valve cover going to the air filter/intake. The pressure is from blowby - combution gases that are leaking past the piston rings and pressurizing the crankcase. If not vented by the breather hose, the blowby will build up enough pressure to force oil out the dip stick and even blow out the oil seals.

You don't say what engine you have, but many 617s have an oil serarator in the air filter that removes the excessive oil from the blowby and returns it to the crankcase. The de-oiled blowby is then directed to the intake where it is burned in the engine. If the oil separator is badly gunked up - it can reduce the blowby venting resulting in higher crankcase pressure.

Oil dipstick level can't be measured with the engine running because of all of the oil being spashed around by the crankshaft anf blowby gases. To measure the dipstick oil level the engine must be off and allowed to sit a few minutes to allow all the oil in the upper engine time to drain back into the crankcase.

You can check for blowby by letting the oil fill cap sit loose on the valve cover hole while the engine is ar idle. Its OK for the cap to dance around a little but it shouldn't blow off.

Good Luck,

Joseph

[nyko46]

Originally Posted by jkubica

Hi
The idea is not to allow any pressure to build up in the crankcase - that's the purpose of having the breather hose on the valve cover going to the air filter/intake. The pressure is from blowby - combution gases that are leaking past the piston rings and pressurizing the crankcase. If not vented by the breather hose, the blowby will build up enough pressure to force oil out the dip stick and even blow out the oil seals.

You don't say what engine you have, but many 617s have an oil serarator in the air filter that removes the excessive oil from the blowby and returns it to the crankcase. The de-oiled blowby is then directed to the intake where it is burned in the engine. If the oil separator is badly gunked up - it can reduce the blowby venting resulting in higher crankcase pressure.

Oil dipstick level can't be measured with the engine running because of all of the oil being spashed around by the crankshaft anf blowby gases. To measure the dipstick oil level the engine must be off and allowed to sit a few minutes to allow all the oil in the upper engine time to drain back into the crankcase.

You can check for blowby by letting the oil fill cap sit loose on the valve cover hole while the engine is ar idle. Its OK for the cap to dance around a little but it shouldn't blow off.

Good Luck,

Joseph

Thanks for your helpful post.
My engine is a 617 and it has 244 Kmiles I just mentioned that I checked the oil levelwith engine running and also with engine not running to see the difference with breather hose in place and without breather hose and the result was the one that I post on my thread. If I remove the oil fill cap from valve cover it will dance but not poping out of the valve cover. About the oil separator, I would like to be informed how is the best way to have it cleaned to eliminate one more chance of low ventilation. If I run engine without breather hose from top of the valve cover, oil will not raise on the dipstick.

[SD Blue]

Originally Posted by nyko46

................. If I run engine without breather hose from top of the valve cover, oil will not raise on the dipstick.

Before you go to the trouble of a compression test, etc..., You need to find the blockage. It could be the breather hose and the oil separator drain.

The breather hose should be removed and flushed with brake cleaner to ensure that it's not obstructed. Also, make sure there isn't something pinching it with the hood closed. (such as a loose hood pad)

The oil separator, inside the air filter housing, is very simple. The oil mist condenses on the inside and is fed by gravity, through the drain tube, back to the crankcase. There are usually 2-3 areas of concern with that system. First, ensure there are good o-rings on the drain located on the bottom of the air filter housing. Second, check the bottom of the drain tube where it enters the crankcase. Last, on the next oil change, run some of that "engine flush" through the tube after you have drained the oil. If that tube has been open to the air, it may have collected dust and clogged. (mine had this problem)

[nyko46]

SD Blue:
As you are in the Fort Worth area in Texas, do you know some good guy that have knowledge in Mercedes Benz diesel engines?
I am going to change my rear oil seal (the rope seal) but every shop that I know are scary to touch diesel engines and other that work with diesel engines want to charge more than the price of the used car. I found a guy in Richardson-TX that took two days to give me a quote price for that job and asked me $1500.00 just to replace that seal.
I will also need to change the bushings on both sub frame (the aluminum piece in a shape of L ) but I have the spare parts for this job and also the real seal.
If you know someone that can do it, please let me know.
Thanks.

[Cr from Texas]

Originally Posted by nyko46

SD Blue:
As you are in the Fort Worth area in Texas, do you know some good guy that have knowledge in Mercedes Benz diesel engines?
I am going to change my rear oil seal (the rope seal) but every shop that I know are scary to touch diesel engines and other that work with diesel engines want to charge more than the price of the used car. I found a guy in Richardson-TX that took two days to give me a quote price for that job and asked me $1500.00 just to replace that seal.
I will also need to change the bushings on both sub frame (the aluminum piece in a shape of L ) but I have the spare parts for this job and also the real seal.
If you know someone that can do it, please let me know.
Thanks.

Mine goes to Dave's Foreign Car Service, 400 South Elm, Denton 940 387 2886. Brian usually does the diesel work.