What is the exact reason for foamy oil out the breather tube?



12 replies to this topic
  • MN_Kevin

Posted February 07, 2001 - 01:42 PM

#1

I know what a mixture of oil and water make. I learned it a long time ago when the block cracked on my 1970 Camaro. I too have seen the stuff excreet from my vent line. I do know it is common.

Why though? I initially thought head gasket leak. The engine oil is still a pretty black with little shiny specs...oops, that was my neighbors YZ250 stroke after it seized. :)

Anyone know the exact reason...Clark or James?

------------------
'99 WZ with all YZ mods, FMF PowerBomb header, Stroker SX-1 silencer, SS front brake line, forked over by Pro-Action, OEM YZ tank and IMS seat.

  • Boit

Posted February 07, 2001 - 02:01 PM

#2

Kevin: I realize you didn't ask me but, I'm gonna give my observations anyway. I've noticed that my breather tube will emit that milkish discharge at times. It's more prominent when the ambient temperature is cool...or cold. As hot oil cools, it absorbs moisture. If the outside temperature is cold and also humid, this milkish discharge is more apt to occur. At any rate, it's prefectly normal for this engine venting design.


I remember hearing as a teen working at a full service gas station back in the late 60's and early 70's about how important it was to thoroughly warm up an engine before stopping it...and that that frequent short runs on an engine were extremely harmful. This was right on the money! When an engine is brought up to normal operating temperatures and then shut off, the slow cooling will cause a gradual vacuum effect drawing in outside air with it's accompanying moisture. This moisture condenses and leaves small water droplets at the bottom of the oil pan(crankcase). This happens to a greater degree in high humdity environments. Short engine run times never gives the engine enough time to evaporate these droplets out and sludge begins to accumulate. If you've just ran your engine really hard, try to give it a cool down time by putting around at the outskirts of the pits before shutting it down and see if the discharge goes away. I'd say the extreme temperatue difference is what's causing the discharge. Try to avoid shutting down the engine when it's really really hot.

[This message has been edited by Boit (edited 02-07-2001).]

[This message has been edited by Boit (edited 02-07-2001).]

  • Guest_Guest_*

Posted February 07, 2001 - 03:57 PM

#3

I know you didn't ask me either, but it sounds like your bike has the CLAP.

  • Vincent

Posted February 07, 2001 - 04:17 PM

#4

Another really helpful unregistered input.

  • Guest_Guest_*

Posted February 07, 2001 - 05:53 PM

#5

Gee Vince, maybe Brian will close this thing to members only. I would think that would make you happy. But then, what would you do next? I'm sure you will tell me.
Where is your sense of humor? Or do you know what that is?
I guess being a member makes you special.

  • Vincent

Posted February 07, 2001 - 06:25 PM

#6

I rest my case.

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  • mcarp

Posted February 07, 2001 - 07:25 PM

#7

Clyde- Go slither away...

Kevin-

I believe what has been said is correct. I might add another issue that could be confusing, or more likely adding to the symptom is frothing.

As air is mixed with the oil coming out the breather (from churning in your crankcase like a blender), it will change the appearance. Just like the little faucet filter aerates (I know I spelled that one wrong :) your tap water, it appears cloudy coming out, yet clears up when the air bubbles settle to the top of your glass.

Chances are it's more water condensation than air as mentioned above, but it can be a factor. Anyone else agree or has Sammy Adams hampered my reason?

  • Team_Oatmeal_Pie

Posted February 07, 2001 - 07:55 PM

#8

Foamy white stuff?
Damn Kev you stud, last time I saw that stuff it was coming from out of a hot 19 year old chick, but you.... must be really pouring it to the wr, I've tried everything and just cant seem to massage my blue lady to do the same, whats your secret?

Actually I run a filter on the end of my breather, looks like a mini K&N but round, seems to keep it clean. Going to install my ims tank and seat tommorrow if I can get out of vegas on time. Those in the know Cheetahs was nice but Crazy Horse was nicer. Uh Huh...

  • Bruce_in_Phoenix

Posted February 07, 2001 - 08:14 PM

#9

When your piston goes up it pushes air out of the valves when it goes down it pushes air out the breather. When your motor is spinning at 10,000 RPM the oil is flying all over the place in your motor. Well the cam chain brings oil up to the top of the motor and some of the mist ends up in the line and makes its way down the tube onto your skid plate or boot.

  • Bruce_in_Phoenix

Posted February 07, 2001 - 08:14 PM

#10

When your piston goes up it pushes air out of the valves when it goes down it pushes air out the breather. When your motor is spinning at 10,000 RPM the oil is flying all over the place in your motor. Well the cam chain brings oil up to the top of the motor and some of the mist ends up in the line and makes its way down the tube onto your skid plate or boot.

  • Bruce_in_Phoenix

Posted February 07, 2001 - 08:28 PM

#11

When your piston goes up it pushes air out of the valves when it goes down it pushes air out the breather. When your motor is spinning at 10,000 RPM the oil is flying all over the place in your motor. Well the cam chain brings oil up to the top of the motor and some of the mist ends up in the line and makes its way down the tube onto your skid plate or boot.

  • MN_Kevin

Posted February 08, 2001 - 12:34 AM

#12

OK, aerated oil w/ maybe some moisture in it.

I hope the aeration is AFTER the lubrication part of the oils job.

  • mcarp

Posted February 12, 2001 - 07:09 PM

#13

I doubt it, Kevin. It probably aerated once it reaches 2-3 minutes running time. ALL vehicles do this to some extent.

Here's a test. Drain the oil in a clean pyrex pan. Let it sit for a few hours. If the cloudiness/milky stuff dissappears, it'a just air. If it's there overnight in your cold NH garage, heat it on your stove (mid heat, 7-10 minutes) and see again if the milkiness goes away. If it does, it's water condensation. If it doesn't it's coolant.

I think it's just a little air and little water condensation, no worries...




 
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