YZ426f coolant in oil

3 replies to this topic
  • rbecker19

Posted February 21, 2016 - 04:03 PM


I am in need of help i have a 2001 yz426f that i bought a while back and i got done with riding for a weekend and when i went to change the oil it was very white, it looked like milk and if i look really close i can see coolant bubbles in my oil, is this a blown head gasket? water pump seal? any help or advice would be greatly appreciated!  

  • Thumbster21

Posted February 21, 2016 - 09:22 PM


The oil in my 09!yz250f looked like chocolate milk when I bought it. I feared the worst! I knew it had to be an internal cracked head or something gawd awful expensive. I couldn't see anything leaking.
Luckily I was wrong. Just a blown head gasket. It gave me a chance to become intimately familiar with my engine though. I bought a full gasket/seal kit and replaced everything that I could without splitting the cases. I went with the OEM gaskets and haven't had any trouble since.
I also thought that it could be a leaking water pump seal but there's a drain hole under the water pump and nothing was leaking out. I had hoped it was the water pump because that's easier to fix.

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  • grayracer513

Posted February 22, 2016 - 07:34 AM


Water pump seals won't contaminate the oil because there's an escape port (leads to the "weep hole") between the coolant and oil seals to prevent that.  The head gasket is the most likely culprit.  There can be a coolant leak between the crankcase and either the base gasket or the right side cover behind the water pump where the coolant passages are, too, but these are not common except when assembly errors are made. 

  • rbecker19

Posted February 22, 2016 - 03:10 PM


hmm makes me thing because i had just gotten my bike back from the shop a few weeks before and this was the first real hard ride with it but rode it around my neighborhood alot after i got it back

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