Oil check 03 yzf 450

11 replies to this topic
  • 03yzf450-kuke

Posted March 18, 2015 - 03:42 PM


Was wondering if anybody knows is there any thing in the 03 yzf 450's oil tank that keeps oil from quickly running back down into the crankcase? I run the bike for couple minutes and shut down. If I check oil right away it reads full if I wait thirty seconds it reads half way and another ten seconds or so it reads empty. Hard to tell what my oil level is when it drains back to crankcase so quickly.any input would be much my appreciated...hoping to hear from grayracer513 as I have read MANY of your posts and feel you know your way around the yzfs very well. Thanks.

  • grayracer513

Posted March 18, 2015 - 03:54 PM


Nothing in the oil tank, but there is in the engine.  In the picture here, items 25-27 are the low pressure check valve that is intended to do exactly that.  25 is both a seal and a seat for the check ball.  It could be missing, damaged, or have something lodged in it. 
The second possibility is the feed oil pump (There are two pumps in the engine on the same common shaft. The feed pump is the one that unbolts off of the crankcase in its own housing as an assembly.  Read:
http://www.thumperta...714#post3117714 ) Oil flows from the tank, through an external line on the right side, then up to the feed pump.  With the engine off, the pump rotors create an obstruction to flowing farther, but not a complete obstruction.  Oil can leak past the pump because of the pump's internal clearances, but then it runs up against the low pressure check valve and gets stopped.  If the check valve holds, the only other path is out of the oil pump around the pump shaft. 
In order for the pump itself to leak that much oil, it would have to be very badly worn.  The most likely suspect is the low pressure check.



  • 03yzf450-kuke

Posted March 18, 2015 - 05:11 PM


That's awesome gray thank you so much that is what I suspected but cannot find it anywhere in my manual I've bin trying to figure this one out for days now. Only thing is now is I still don't have a pic showing me where the check valve is located. Is it just inside the side cover from the oil feed line?

  • grayracer513

Posted March 18, 2015 - 06:27 PM


Oops.   Fixed.


The hole just below the bore where the valve sits is the port the oil line connects to.

  • 03yzf450-kuke

Posted March 19, 2015 - 02:42 AM


Sry to bother you gray but when I click on this picture it won't show me 25-27 it only shows me the middle and I can't scroll side to side. Also another question is other than not getting an accurate oil level reading can this problem of it leaking back down cause any damage to my engine on startup?

  • grayracer513

Posted March 19, 2015 - 06:17 AM


Using a phone?  Get on a computer. 


Probably no real harm.  You may burn a bit of oil until it all gets back in the tank, and you should be a little cautious on startup as far as how much load you put on it right away.  But either condition could also indicate that oil isn't being delivered at the correct rate due to the leakage at either the seal or the pump, so you should investigate.

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  • 03yzf450-kuke

Posted March 19, 2015 - 06:46 AM


Great thanks gray I knew you would be able to help me out ur the man gray so glad I finally joined tt

  • 03yzf450-kuke

Posted March 22, 2015 - 06:10 AM


Hey gray so In my investigating my check valve seems OK the ball and seal are still there . is there any chance this is just happening because I'm using thinner oil like 10w30 for the cold season?

  • 03yzf450-kuke

Posted March 22, 2015 - 06:41 AM


Also my oil feed line bolt is stripped and a cc cover bolt near the feed line is stripped, they won't torque to spec. Would that possibly have anything to do with it?

  • nucular

Posted March 22, 2015 - 06:57 AM


My 08 did the same thing. Replacing the check valve seal,ball,and spring took care of it.

  • grayracer513

Posted March 22, 2015 - 07:54 AM


Hey gray so In my investigating my check valve seems OK the ball and seal are still there . is there any chance this is just happening because I'm using thinner oil like 10w30 for the cold season?


No. It should hold 10w-whatever for at least a day or two, even in summer.  The spring and ball are probably OK.  Replace the ball seat/seal and check your oil pump.  This time, use a new gasket on the cover.  This is the second time I know of you've had it off.

  • 03yzf450-kuke

Posted March 22, 2015 - 08:05 AM


Yes I will be changing the seals this time as it is my third time with it off and the gasket is now pretty stretched and no longer will line up with bolt holes properly. I'll replace the check valve seal too and hopefully this fixes it. I have looked at oil pump and it looks fine and it did hold oil in the tank before and haven't rode much since then so I'm thinking it must be that seal since it only started happening recently

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