Greyish liquid for Breather Hose

6 replies to this topic
  • Dusty_Roads

Posted June 13, 2007 - 05:31 PM


My sons' freind just bought a used 2002 YZF426. I didn't see it, but after a short ride a greyish liquid came out of the cam cover breather hose. The liquid may have been oil w/ water or coolant in it, but I'm not sure. Drained some oil and looked under the cam cover. Both looked ok. Coolant was filled up to the cap. Not good. Possibly over filled with oil. Bike is actually in good shape and seems to have have fewer hours than my son's 01. Could there be a possible problem with gaskets or something? Any suggestions? Are we over reacting.

  • TeamPrecisionIT

Posted June 13, 2007 - 05:45 PM


Could be caused from the humidity of the bike sitting for so long and made the top end have some mixed oil/water which once was heated, came out of the breather tube. Do an oil change or two and it shouldn't happen again. And if this was an indication of the previous owner's maintenance record, I would go ahead and perform a complete service of everything that you can do. Regrease bearings, swingarm pivots, swingarm axle, replace chain/sprockets, drain and refill coolant/water, clean/rebuild carb, etc.


  • grayracer513

Posted June 13, 2007 - 07:34 PM


Coolant was filled up to the cap. Not good.

Why would that not be good? The coolant should be full. If there was oil in it, the oil would have floated to the top and slimed the bottom of the cap.

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  • MaDgamEr

Posted June 14, 2007 - 01:59 AM


Grayish oil could also be an indication of high metal content in the oil. If you have a coolant in your oil, the oil will tend to be lighter on colour and "frothy".

  • Ga426owner

Posted June 14, 2007 - 06:06 AM


grey color could be the result of water sucked up into the motor also - through that breather tube....never stop and restart these in water or mud holes:prof:
I would drain all the oil, inspect /clean oil fiter and refill with good oil.
I had this happen myself...took me like 4 oil changes to get all the moisture out

  • mkporn

Posted June 14, 2007 - 06:40 AM


It ain't no thing......I know exactly what you are seeing, a little drip of grey liquid in the hose and a small drip... This is not a huge issue. What happens is, air is being pulled and pushed thru this hose every time the piston moves... Due to tempature change between the outside air and the inside air, you get condensation in the hose. The motor oil gets a bit of a mist in the motor and some of this is pushed out the hose.....The moisture in the hose and the oil mix and you a get a small amount of milky grey stuff...

This is by no way an indication of how the bike is maintained nor is it a problem if there is no milk in the rads or in the actual motor.....

Next time you ride in the rain, put a clean pan under the hose when you stop, you will see what looks like a huge oil slick (rainbow) develop in the pan...Completely normal. This is why emissions bikes have the breather retuning to the motor, don't want that litrtle bit of oil to get out...

  • blue9red9

Posted June 21, 2007 - 02:16 PM


I've seen it on my floor too just like you are saying. It comes and goes depending on the time of year. It's not always there. I never paid it any mind because it's not all the time.

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