2008 yz450f no oil pressure from check screw


14 replies to this topic
  • yamie

Posted April 28, 2013 - 08:47 PM

#1

Hey guys, sorry to repost this similar topic, but trust me I have read every topic on this site regarding this issue and have tried all suggestions.. Really stumped , here's my issue.

Recently rebuilt my motor (new crank and bearings and big bore kit), was working fine. Have less than 10 hours on the rebuild, and now there is no oil coming out of the check oil screw by the carb. Bike still runs good, I drained the oil several times, followed the proper steps on oil changes from the manual, but no oil comes out when I take out the screw. I have oil coming out of the bottom hole when taking out the filter. I have taken off the vent hose and I cannot blow through this when the dipstick is in. I can take out the dipstick and blow through the vent line with no problem. With the bike running I can take out the dipstick and oil is shooting out (which leads me to believe I am getting good oil returns). I pulled off the left side crankcase and while kicking the bike over there is oil coming out of the return hole as well. I also can see the screen from here and the screen looks like it is not obstructed in anyway. I cannot see any holes by the balancer as some other post has stated to look for. So I took off the top end and the cams do look like they have oil on them. I also tried to blow air into the oil pressure check screw and didn't change anything. Not sure what else to look for.

Sorry again for a similar post, but i'm stuck :(

  • grayracer513

Posted April 29, 2013 - 06:10 AM

#2

Model & year?

  • FinchFan194

Posted April 29, 2013 - 06:18 AM

#3

Thread title.

  • grayracer513

Posted April 29, 2013 - 09:33 AM

#4

I wish they wouldn't do that.

So, it seems obvious enough that the return pump at least is working. It also stands to reason that the feed circuit is at least partly functional because there is something for the return pump to return.

The check bolt on an '08 should be tucked under the intake port on the left side of the cylinder head. The bolt may need to be almost completely removed in order to ooze oil at an idle. Start by verifying oil pressure at the filter. Loosening one or two of the cover bolts should result in a leak when it runs. from the filter, the system goes in two directions, one of which splits off again. The first is to feed the crank pin and piston cooler. The second runs behind the cylinder to feed the transmission, and runs around the base of the left rear head bolt and then up next to it to get to the head. You can verify the oil getting to the trans branch by dislodging the clutch release arm seal or loosening the front sprocket. Either one should cause a leak of pressure fed oil when running.

The things that spring to mind right away as errors that could be made during a rebuild that might cause a lack of pressure to the top are:
  • Gasket sealer blocking the oil flow around the head bolt
  • Head or base gasket flipped over (not sure this can be done and still put it together)
  • Trans bearings in the left case installed backward or unsealed bearings used.


  • yamie

Posted April 29, 2013 - 10:32 AM

#5

thanks for the response.. I checked the gasket above the cylinder head and all holes are opened and gasket is not covering any holes. I loosened the front spocket as well and when starting the bike oil is dripping out of there. The only bearings that I replaced was the crank bearings.

I have the check oil pressure screw taken all the way out and sitting on the work bench, and not a drip off oil coming out. Had bike running for at least 5min, but something seems strange. And the bike seems to be running a little hotter than normal (And I know these bikes run real hot, mine always turns the exhaust bright red lol), but lately just a little hotter. And also a little more noise coming from it on my last ride. not sure if all this is related but there seems to be a lot of similar issues with this year of bike. After reading about this issue I just don't know why I can't get any oil to at least drip out of the screw. (And I have the correct screw taken out for sure lol)

  • grayracer513

Posted April 29, 2013 - 12:22 PM

#6

Remove the filter cover and locate the oil passage next to the upper left cover bolt hole. Remove the pressure check screw. Using compressed air, blow through the oil passage at the right crankcase cover and see if air comes out the check bolt hole.

  • yamie

Posted April 29, 2013 - 02:50 PM

#7

I removed the filter cover and blew air, it mostly came out of the vent on top of the cam cover, so i plugged that with my finger and i could feel some air coming out of the oil pressure screw. didn't blow my hand away but there is some there. Also when i started the bike again i put my finger over the hole (oil pressure screw removed) and I could feel air pressure with just the bike running. but no oil. I let the bike run for 10 min, and then shut it off and waiting 30 sec and checked the oil and it's right at the full mark.

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  • yamie

Posted February 20, 2014 - 11:06 PM

#8

Been almost a year now and I still haven't figured out the issue. I have put about 50 hours on the bike, and the past 2 weeks I have stripped the motor down and split the cases again. I replaced the main oil pump seeing how I had the case apart, replaced a couple other bearing just because... I finally got everything back together, and still no oil coming for the oil pressure screw. Also picked myself up a 2006 yz450f, and took the entire top end off that bike and put in on my 08 (including valves and cams), and still no oil lol. Just wondering if anyone has figured out why this is happening and if I should stop riding the bike and spend the money on a dealer to check it out.. I believe they will rape me cause I had the motor down to nothing, cleaned all passage ways with compressed air, check everything and can't figure it out.. Thoughts???



  • grayracer513

Posted February 21, 2014 - 07:22 AM

#9

Are the cams getting oil?



  • yamie

Posted February 21, 2014 - 02:43 PM

#10

after running the bike for couple mins, I take the valve cover off and the cams do have oil on them. Oil is not dripping off them but they seem to have a light coat. not sure how much oil should be on them but they are for sure getting some



  • jojo1224

Posted February 21, 2014 - 06:30 PM

#11

I removed the filter cover and blew air, it mostly came out of the vent on top of the cam cover, so i plugged that with my finger and i could feel some air coming out of the oil pressure screw. didn't blow my hand away but there is some there. Also when i started the bike again i put my finger over the hole (oil pressure screw removed) and I could feel air pressure with just the bike running. but no oil. I let the bike run for 10 min, and then shut it off and waiting 30 sec and checked the oil and it's right at the full mark.

Do you have pictures from tear down? If you have air coming from check screw you definitely have a leak somewhere. I have not had a gen 2 450 apart but studying the diagrams and some pictures the one spot that would make the most sense to me would be from the spot I have circled in red in the picture below. The red dot feeds to the transmission by the looks of it.
1tChuRT.jpg

(image stolen from ebay user fastguypartsstore)


Edited by jojo1224, February 21, 2014 - 06:31 PM.


  • yamie

Posted April 28, 2015 - 08:39 PM

#12

I am in the process of going through the entire bike again, and found this when taking the right case cover off.  The first pic is my bike, and the second is another pic of a 2006 yz450f. Not sure where oil goes from here but is this the possible issue for no oil to the oil pressure screw? Looks like mine is washed out completely

 

 

IMG_5422.JPG

 

IMG_5423.JPG



  • grayracer513

Posted April 29, 2015 - 06:37 AM

#13

That could do it.  It looks like the piston squirter nozzle is gone.  Number 2 in the picture, PN 2S2-15155-00-00.  Without that there, the socket where it belongs is too big a hole to allow oil pressure to develop.

Attached Thumbnails

  • case.png


  • yamie

Posted April 29, 2015 - 06:47 AM

#14

Could this be the missing piece? I seen it lying on the bottom of the case as I was taking the cover off. Doesn't look fixable, so I'm guessing a new right side crankcase is needed

IMG_5421.JPG



  • grayracer513

Posted April 29, 2015 - 06:53 AM

#15

Yes, I believe that's it.  Examine the case around the area where it's supposed to be pressed in, see if there is damage. Some of the nozzle may still be in the case.  There should be some way to repair the situation, I would think, but you will want a new nozzle.







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