03 oil problem

5 replies to this topic
  • hdkawi

Posted May 24, 2011 - 04:38 PM


2003 yz 450f did my first oil change. went well ,drained tank and filter added new oil and was good to go. rode for a 1/2 day got it stuck in some water and rode it back to camp saw some white oil in the tank so changed oil. this time drained oil from bottom of crank case. no water just dirty. added new oil,started and let it run for 3 or 4 min and no oil in the tank. added oil to the tank, ran it for an outher 3 or 4 min and no oil in the tank. drained the oil becuse there is too much in the sump. bottom line oil goes in and nothing comes out.pulled oil lines off engine and still nothing. is there a blockage or is my pump shot? prime pump?? thanks

Edited by hdkawi, May 24, 2011 - 07:55 PM.
added model type

  • grayracer513

Posted May 24, 2011 - 09:04 PM


You have two oil pumps stacked up on the same shaft. The return pump will sometimes shear the pin that drives it. You might also have a bunch of trash up against the sump screen.

  • hdkawi

Posted May 25, 2011 - 02:23 PM


ya that makes sence thanks a lot . so how to do it? i have a manual and a see how to get to the pump by removing the cover off on the oil filter side. how do you get to the sump screen?

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  • grayracer513

Posted May 25, 2011 - 03:12 PM


When you get the pump opened up, look for a sheared drive pin that anchors the inner (return) rotor to the shaft.

The screen can't actually be removed short of splitting the cases. However, you can see it and the area immediately under it from the left if the flywheel cover is removed. A little custom work with some heat and an old tooth brush...

Also, with the inboard oil pump removed, the large passage that leads out of the pump cavity leads directly to the screen, so back flushing it is possible.

  • hdkawi

Posted May 25, 2011 - 06:40 PM


thanks again lets just hope it's just a sheared pin. that screen is in the same place in the kfx engine i just rebuilt. had to split the case its crazy how much junk builds up down there

  • hdkawi

Posted August 10, 2011 - 08:32 PM


took it all and found no broken pin but i think sump was plugged or a line was plugged blew out with air .anyways works great now thanks for the advice

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