moisture from engine in the oil tank

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Jul 24, 2009
well i found water in the bottom of my oil tank when i drained it today, hundred little balls of it which is too much, in my opinion - according to ... lAej-9jqAQ
yikes- hope that link works - its an oldbrit schematic of the Mk 3 oil and breathing pipes- ive got it plumbed according to the schematic but the line going from the front of the tank to the K&N is too little ,i believe, not pulling enough H2O out of the tank as it goes into the oil tank from the timing box - i was initially thinking about not sending the wet air from the timing chest to give it a chance to pollute the oil with water, but not sure now - but i think if i send a bigger pipe to the air filter itll scavenge "fog" from the oil tank better (mikuni 34 MM)(i plumbed a pipe into the K&N)-
don't poodle around like a nanna and get the oil up to full operating temp and evaporate the water
don't poodle around like a nanna and get the oil up to full operating temp and evaporate the water
I think that there will always be a certain amount of condensation in the oil tank and it should never be hot enough there to boil it off.

Even if there were to be no moisture from the engine, as the tank cools, it will draw moist air in.

Not a bad idea to tug the bike over when draining the oil as the last half inch otherwise remains in the tank. It is also worthwhile removing the rear tank filter and with a lint-free cloth making sure that all the residue is wiped clean from the tank. Simply draining it on the mainstand will not empty it.
It would be interesting to know where you live that you get that much water in your oil and never warm enough to boil it off.
By running the oil line breather to your K&N you are effectively having it breathe to atmosphere--hence, as the tank and it's oil contents cool after running, cool moist air is drawn back into the tank and condenses into water. There is endless debate abiout what is often referred to as "splooge" , for want of a better word, and it always occurs after people modify their intake systems. "all this water-contaminated oil in my motor"--well, by having your engine breathe straight to atmosphere without any form of valving, that is what you get. I was guilty of this--put a breather off my Commandos intake rocker cover into a catch can. It generated great amounts of disgusting emulsified oil. Giving this some thought, and observation, after a while I realised that it mainly occurred straight after start-up. So all I was seeing was what had formed in the hose(and, probably, the rocker cover,)as the motor cooled down from the previous ride. So I put a cheap simple non-return valve in the line, so air could not be drawn back in. Problem solved, all i get in that can now is a tiny amount of clean water, which would only be condensing in the tin itself as it cools down. So the can is irrelevant, and I am going to route the line back into the air filter, with the valve at the very end. And fitted one to my oil-tank breather, on the same principle. Opening your engine internals to the air is really not a good idea, IMO.

After a hard run, the oil in the tank should be over 100°C. I've checked mine with a couple of different thermometers. This would mean the oil temp in the head would be much higher than 100°C. Are you making a lot of slow, short trips? Do you have any engine or oil tank leaks? Maybe starting and idling for a short while, without riding? The oil temperature should be quite capable of boiling off small amounts of condensation.
When buying older cars, (mini's and old fords etc) one of the first things I would do is remove the oil cap and see if it had a mayo covering. It could just be short runs and the bike not getting up to temperature?

I have a lining of mayo oil in the inside of my primary case (when it was last emptied). Any ideas?
100% humidity lately here in Michigan - good thing the oil pickup is an inch off the floor of the tank it allows the water blobs from the timing chest to fall past it , and the screen wont let them in -- it does run pretty hot, but the oil tank stays cool enough to not burn water out - ive got a restriction in my what ill call "oil tank fog pipe" the little one in front of the tank, thinking removing this restriction will allow beetter scavenging of the oily H2O mist to be burned in the combustion chamber - just never been comfortable with water near the oil , and this system sends it straightaway there
i now have a black rubber 3/8ths id hose evacuating H2O from the tank- i cant see in it , i dont worry about it
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