Why would my valve cover gasket blow?-01 yz426

5 replies to this topic
  • matt04xr250r

Posted January 17, 2010 - 04:44 PM


Im in ohio and it was about the 20's out, i was trying to start my 01 yz426f. after i got it started it ran for about a min or less and the valve cover gasket blew. The front little half circle popped out. i was reving the engine slightly after it started also. Do u guys know why this would happen?

also the guy that had it b4 me put cams in it but took it to a shop to do it. i didnt notice that the old gasket was bad or out of place anywhere.
I just replaced it and was going to change the oil and noticed there were metal shavings in the oil fiter. Is this normal? or not?

Let me know what you guys think

  • lumpy790

Posted January 17, 2010 - 05:08 PM


Check to see if the crank case breather hose is pinched or kinked. That would pressurize the crank case and pop the gasket out.

  • Lota Fun R

Posted January 18, 2010 - 12:59 AM


Metal shavings? No, that's not normal.

Gasket popping out? It's likely that the breather tube was plugged. Water frozen in there will do it. I would not be surprised to see that in sub 32f temps.

If that's not the case then it's inferior mechanics skills.

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  • cwcarter

Posted January 18, 2010 - 01:45 AM


You will get a certain amount of metal shavings there, thats what its made for catching clutch particles and other metal suspended in the oil. Like the others have said check the breather and make sure the gasket is mounted properly.

  • grayracer513

Posted January 18, 2010 - 09:22 AM


"Metal shavings" is a broad term, but yes, it's normal. Normal sources of metallic debris large enough to be seen as shavings are the transmission, and in particular, the clutch, both of which share oil with the engine. Small slivers and bits mean nothing bad as long as they show up in the same quantity or less from one oil change to another. If there is a sudden increase in the size, shape, or quantity, it could be a bad sign. Squarish flakes of steel, for instance, can indicate a ball bearing race spalling off metal.

  • matt04xr250r

Posted January 18, 2010 - 03:19 PM


Thanks guys. I cleaned my bike really good and the breather tubes look clear and i think thats all it was.

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