Uh Oh?.....

Changed the oil yesterday (Rotella T 15W-40...) and took it to the track today.  After about 20 minutes on the track...noticed that my front brake was not not working well.  Told myself it was time for some new pads.  About 5 minutes later...I start smelling the motor running hot.  It still did not click.  Then as I am idling in...I notice my boots...forks...everything on the front of the bike...it oiled up.  I stop the bike...  The breather bolt on the top of the oil tank came off...and it spit out almost all the oil!  The motor was still running fine....

I pushed it back in and loaded up.  When I got home...I drained what was left of the oil...which was about 200cc.  Gotta figure there was another 200 cc in the motor...and mayben 100 in the filter.  To all told...I ran the thing down to less than 25% of its oil.  The oil that drained out was pretty dark...

So...my question is this.  When you run a YZ250F low on oil...what is the most likely thing that will be damaged. Let me know what you think...and I have no experience with running 4 strokes out of oil!  I would assume the following order of most likely damage.

1.  Camshaft journal to aluminum cylinder head/cap bores.  Measure with a plastigage...
2.  Upper rod bearing / wrist pin.  Just replace with upper end.
3.  Clutch.  I was probably looking at a new clutch soon...
4.  Rings.  Replace with upper end.
5.  Lower rod bearing....new pin and cage.
6.  Lower end main bearings... and tranny bearing.  I hope not...I really dont want to change these at only 85 hours...
7. Anything else...??

The motor had 85 hours on it...and I was getting ready to tear it down for a rebuild anyways....  it looks like the rebuild might have gotten a lot more expensive.  I would be surprised if the clutch was not fried now...

Should I just tear it down 100% and measure everything...to be sure?

The only thing that might save me was that during this practice session...I was working on th same rutted corner over and over...and not going very fast at all.  1/2 the time I was tooling around at idle reentering the track between other riders...  Hopefully that saved me from destorying the motor....

Edited by Blutarsky, 12 August 2012 - 03:23 PM.

Don't panic.  Change the filter, fix the leak, fill with fresh oil and run it.  Unless it gives you some indication that something is really wrong, there is a good chance it is just fine.

this exact same thing happened to my frends '11 yz250f he just replaced the leaking part and everything was fun.  ran it for a few more months.

so you had some oil come out the bottom.  That means there was some fresh good quality oil still running through the oil pump.  Fix the leak and top off the oil and  rock n' roll!!!
Let's say for a moment you didn't have any oil in the oil pump, You still had oil built up in the bearings and clutch and in the top end.  Lots of little puddles of oil in that vibrating engine splashing around a lubing everything.
Consider yourself lucking you found the problem before Boom.
Usually the first things to get damaged are in the top end.  If your concerned take the valve cover off and inspect cams and stuff.  Easy and Cheap.
A couple weeks ago I was trail riding in the middle of nowhere.  I dropped my bike and picked it up before anyone could see me.  A mile later I got a flat tire.  When I started changing the tube I notice oil on the ground.  I had a hole in my engine cover.   Flat tire saved my engine.

Well there is two ways you can go about this.

1.) You can play the ignorance game and throw some oil in there and pray to whom ever you pray to that nothing happens in the near future.

2.) Take off your valve cover and inspect the cam and journals also the cam bearings. If damage is found keep working down. You may find minor damage and fix it now instead of minor damage ending in catastrophic failure at the absolute worst possible time.

Thanks guys. I will check the cams journals, bores and tolerances and see what it looks like.  Crossed fingers....

swede gave you perfect advice.  follow it!

Swede73, on 12 August 2012 - 08:45 PM, said:

+1.  Not just looking for damage from lack of oil, but also from any contamination that got in through the vent bolt hole.

peski111, on 13 August 2012 - 05:23 PM, said:

If anything got in through there...it should be trapped in the oil tank.  I will flush it with diesel to clean it out.....

I pulled the valve cover off, and did a detailed inspection on the cams.  They are perfect....

• Everything was still very wet with oil
  
• Camshaft journal to cap clearances were like new...  0.0012" for the exhaust cam, and .0016" for the intake (measured with plastigage...)
  
• Camshaft bearing journal ODs were perfect at 0.8649"
  
• There was some polishing on the exhaust cam bearing journal OD opposite the cam lobe.  This is probably from starting the motor and the cams spinnng a bit before there is oil up there....not due to my low oil event. There is no difference in diameter on the bearing journal ODs in line and perpendicualr to the lobe...so it is just polishing.
  
• The cap surfaces all look perfect.
  
• Cam lobe look perfect
  
• Rolling element bearings felt perfect
  
• I even checked the valve clearances...not that that has anything to do with the low oil issue..  They were all within spec.

So....the camshafts and cylinder head have no issues.  Should I assume that the rest of the motor is probably AOK?

My plan is to flush the oil tank, change the filter, re-fill with oil...then run it a bit....and then change the oil again while it is hot to flush things out...then go ride....

Edited by Blutarsky, 13 August 2012 - 11:32 PM.

It's hard to kill a Yamaha even if you try.

You ran it low on oil not out of oil.

beezer, on 14 August 2012 - 07:26 AM, said:

Yep...that is why I chose Yamaha.....

Finally, I'm not the only one who oils his boots!

A couple of years ago a buddy ran his YZ250F with almost no coolant in it for at least an hour.  He filled the radiator up from his camelback and off he went.

The thing is still running.

beezer, on 15 August 2012 - 12:04 PM, said:

cool story bro

I had an brand new 09' a few years back and the oil tank screw decided to fall out on the first breakin/ride day at Southwick. Came in after 5 laps and noticed oil all over the front of the bike...screw missing and hole full of sand. Flushed tank/oil/filter a couple times and never had an issue. Talk about shitting your pants!!!