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08' CRF 250R has milky yellowish oil (only in engine)

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Recently purchased a 2008 CRF 250R that wasn't running. Hasn't been ran in two years. It had a milky oil in it when I bought it but wasn't too worried. When I brought it home I cleaned out the carb really good, put new gas in it and changed the oil and filter. Got it running after kicking it numerous times but it runs great. After the fresh oil change I just did it still has a milky oil in it ( in the engine only though ) . I was thinking it could be the waterpump seal but if that goes bad would it go into the transmission oil as well ? I've just heard that it can be the waterpump seal or top end gasket. Can someone help me with this ?

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Unless the "weep hole" is plugged no water can get into the cases. Milky oil is definitely a sign of water in the oil. Most often a bike that has been overheated will damage the head gasket and that can allow water and oil to mix. You can pressure check the cooling system to find out. Was the coolant low?

Whenever the engine oil looks nasty for whatever reason (new purchase, bike took a swim in a creek, etc.) I will run about 30% ATF (automatic trans fluid) mixed into some cheap automotive oil. Fill the motor to proper level, start and let it warm up to normal temp, then I shut off and allow the bike to cool and then drain the oil. I do this 2-3 times depending on how it looks when it drains out. I follow up with a fresh high quality bike specific oil and change it once more after a good long ride.

ATF is very high "detergent" and helps loosen up and remove all the nastyness. I personally dont ride the bike with any significant amout of ATF even though it most likely wouldnt harm anything. I simply use it as a flushing agent.

Edited by Justin Pearson

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Thanks for the quick response. The coolant level was a little low when I first checked it but seeing how it hasn't been ran for a couple years it could be down a little. I added a little Honda coolant in it so it was an inch under the cap. I was thinking of doing a few flushes of oil but wasn't sure to use an additive. I'm thinking too that there is some nasty stuff still tucked in the engine and a little water so its probably just picking it up when it gets warm and mixes. I'm sure it only takes a few drops to make it milky. I will try to do a couple oil changes with the cheap oil and atf and see how that works. I just don't feel like pulling the engine apart and trying different gaskets.

Just to confirm though. If the water-pump seal went would it ruin the transmission oil or just work its way into the engine oil only ?

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Again, I appreciate the response. I did exactly what you said and the Honda oil I put in last is clear as day. I'm sure after sitting for 2 years the engine built up condensation or it was sunk in water and was just stuck in all the different parts in the motor and needed to be flushed out.

Thanks again !!

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If the water-pump seal went would it ruin the transmission oil or just work its way into the engine oil only ?

Neither, there is a "weep hole" that works as a drain and early warning. If the seal is leaking the water drains out the weep hole onto the ground and gives you a heads up something is wrong. The only way for a water pump seal leak to push water into the engine is if someone plugs the weep hole (surprisingly common). I suppose someone who doesnt understand the reason coolant is dripping out the weep hole might think if they plug it, the leak will stop. Which it will, sort of, it will be pumped into the crankcase instead! xD

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Again, I appreciate the response. I did exactly what you said and the Honda oil I put in last is clear as day. I'm sure after sitting for 2 years the engine built up condensation or it was sunk in water and was just stuck in all the different parts in the motor and needed to be flushed out.

Thanks again !!

*** Can close thread **

Hopefully it was just condensation. If there was a sizeable amount of water left inside for a long time that a lot of things can be damaged inside. If you dont jump the bike you may chosse to just ride it. If the bike spends anytime in the air I would definitely recommend at least pulling the valve cover, and both crancase covers and take a good look inside to see if anything looks bad (rust, corrosion, etc.)

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