WR450 - blown head gasket. Is this a crankcase vent issue?


6 replies to this topic
  • ack1961

Posted February 19, 2012 - 08:51 AM

#1

EDIT: Title should read "Valve Cover Gasket", not "Head Gasket"

All,

I apologize up front, as I don't know a lot about 4-stroke bikes.
A buddy was riding my '03 WR450 yesterday and we came to a stop (after a stream crossing) and someone else noticed oil spitting out one of the half moon rubber nubs on the valve cover gasket. The rubber nub had torn away from the gasket itself and was sitting at a 45 degree angle. It is the side closer to the radiator, which I think is the exhaust camshaft cover.

We were able to press it back in and ride back to base. Upon closer inspection, we see that a vent hose (which runs outside of the skid plate) had been crushed/pinched closed (probably at a log crossing). I think it's labeled as the "Cylinder Head Breather Hose" in my manual.

Not jumping to conclusions, but I think that the pinching of this breather hose caused so much back pressure that the gasket blew out (I'm guessing that's design intent).

Anyone else ever experience this?

My plan is to:
- Flush the oil a few times - we don't know how long that nub was off and some of the water crossings were deep & messsy
- Remove the cylinder head, replace the gasket
- Check the Valve clearances (something new to me as well)
- Un-pinch the breather tube and re-route it inside of the skid plate

Should I have other causes for concerns?

Thanks, Steve

Edited by ack1961, February 19, 2012 - 04:12 PM.


  • Leardriver

Posted February 19, 2012 - 10:08 AM

#2

The head gasket, which seals the cylinder to the cylinder head, can withstand insane pressures. A pinched vent hose may cause a crank seal to blow out, but that's not the symptom you are having.

I would unpinch and re-route the hose, clean up the oil mess, change it if you think you were in deep water, and ride it again. If there is a persistent leak, it will become apparent soon enough.

Riding in mud and deep water gets very expensive fast. Those are elements that you don't want in your engine, and you are rolling the dice.

  • Birdy426

Posted February 19, 2012 - 10:57 AM

#3

It sounds like you are talking about the valve cover gasket, not the head gasket...
Yes, pinching the breather will cause crank case pressure to build up and will blow out the half moon portions of the valve cover gasket. If the gasket is damaged, replace it. While you have the valve cover off, look fr dirt and crap in the area. Clean as appropriate. Change the oil a couple of times to be sure there's no water in there, and change the oil filter as well. It mihgt not hurt to clean out the screen filter at the bottom of the frame reservoir as well.

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  • ack1961

Posted February 19, 2012 - 11:05 AM

#4

It sounds like you are talking about the valve cover gasket, not the head gasket...
Yes, pinching the breather will cause crank case pressure to build up and will blow out the half moon portions of the valve cover gasket. If the gasket is damaged, replace it. While you have the valve cover off, look fr dirt and crap in the area. Clean as appropriate. Change the oil a couple of times to be sure there's no water in there, and change the oil filter as well. It mihgt not hurt to clean out the screen filter at the bottom of the frame reservoir as well.


Awesome...thanks.
Yes, the Valve Cover Gasket - you are correct...and thanks for the good advice.

  • ack1961

Posted February 19, 2012 - 11:06 AM

#5

Riding in mud and deep water gets very expensive fast. Those are elements that you don't want in your engine, and you are rolling the dice.


What does that mean?

  • MANIAC998

Posted February 19, 2012 - 12:27 PM

#6

A lot of people re-route the breather up and into the airbox, so as to keep it from sucking water up and into the head if you should happen to stall out in a stream. Maniac

  • ack1961

Posted February 20, 2012 - 06:25 AM

#7

A lot of people re-route the breather up and into the airbox, so as to keep it from sucking water up and into the head if you should happen to stall out in a stream. Maniac


Thanks. Will do.




 
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