yz426f blowing head gaskets



3 replies to this topic
  • superjetrider18

Posted April 19, 2013 - 08:38 PM

#1

I got a yz426f that i picked up a couple months ago, was mixen my oil and coolant together. After changing all the gaskets, and being timed and gettin the valves adjusted, it started right up, however, about a minute later it started leakin oily coolant outta the head gasket, so I immediatly shut it off, but then tried starting it after, it would just backfire, but wouldnt start. Now , I took it apart, and found out that the gasket was blown. Anyone have any ideas why I keep blowin my gaskets? Any and all ideas, I gotta figure out the problem

  • RMC233

Posted April 19, 2013 - 08:43 PM

#2

Have your head resurfaced (probably warped) and make sure you torque the bolts/nuts properly and to spec.

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  • tranqwhl

Posted April 19, 2013 - 10:26 PM

#3

thin coat of the permatex copper coat, or whatever it's called now, on both sides, let dry, install; and no more blown head gasket.

I had similar issue; not again since I started using that stuff.

(could be something else too, like warped head)

  • marv02

Posted April 20, 2013 - 07:28 AM

#4

Get a FLAT surface get some 400 Grit sand paper lay it flat spray some WD 40 of the sand paper then place the head down flat and with the gasket mating surface flat down on the sand paper move the head in a figure 8 Patten until the head is flat then use some 600 grit for final pass.

If the Cylinder off do the same for it When I rebuilt my 426 I noticed even the bottom of the cylinder was not totally flat I made a fixture for it to make it flat I also did the center cases as long I had it all a part.

Nothing leaks.

MAKE SURE what ever you end up using it FLAT to put your sand paper on I had a piece of marble tile from Home depot work make sure it flat I used a flat piece of .250 thick Aluminum plate last time.





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