Oil Filter Well And Direction Of Flow

4 replies to this topic
  • bigred455

Posted August 11, 2008 - 09:15 AM


I have looked over the oil flow diagram in my service manual numerous times. For the life of me I cant seem to figure out how oil enters the well and where it exits. I have looked at the passages on the filter cover and cases,I dont want to know where the oil flows after it leaves the well,just how it enters,how it flows thru the filter and leaves.

If you are looking at the oil filter well,you have a small hole inside the well for the filter drain bolt which I PLUGGED up. To the right of that is a larger hole,does oil enter the well and hits the filter?,and then goes thru the holes in the filter cover?.Then oil gets distributes through the cases and the rest of the motor?. Does oil get filtered through the sides of the filter? What path does it follow in the well and which path through the filter? SCHOOL ME:confused:

  • grayracer513

Posted August 11, 2008 - 09:38 AM


Oil comes directly from the feed oil pump into the filter well through the larger hole. It passes through the element and out through the outboard end of the filter into the cover.

From the cover, it branches in two directions. The first is through the hole at 6 o'clock, next the the troublesome lower cover bolt. This routes downward through the right case cover to the end of the crankshaft, where it feeds through the right axle to the rod bearing.

The second branch flows back through the right case cover through a passage at 10 o'clock. In the early YZF's this passage feeds into the external oil manifold that lubes the trans and top end. In '06 and later 450's the passage continues into the crankcase, where it meets internal passages that do the same thing.

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  • bigred455

Posted August 11, 2008 - 09:47 AM


Hey grey that is what I thought how it enters. THANKS:thumbsup:

I am still a little confused,once it comes thru the larger hole it goes thru the right side of the filter and out the open end of the filter? I would have to say no what is the purpose for the other side of the filter,does it hit both sides of the filter? I totally understand the rest of the path, if you don't mind ONE MORE TIME.:)

  • grayracer513

Posted August 11, 2008 - 09:53 AM


Oil fills the well and flows through the filter media on all sides, then out through the center on the cover end. In the event that the filter becomes too restrictive, and the pressure drop across the media exceeds about 5-8 pounds (typically), the bypass valve at the inboard end of the filter will be forced open, and unfiltered oil will enter the filter and pass through to the lube circuit.

  • bigred455

Posted August 11, 2008 - 09:56 AM


Awesome,clear as a bell. Thanks for the 2nd comeback.:)

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