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enduro400

YZ 426 Head Gasket Leaking?

3 posts in this topic

My friends 426 blew a head gasket (so he says). He asked me to help him with the repairs. He ran it hot and now it leaks coolant, still runs but leaks. Just wondering if this is a "easy" job that a mechaniclly inclined person could do himself? What are some things to look for while we are tearing it down? Any machine work to be done (i.e. resurfacing the head) before reinstalling new gasket? Thanks in advance :)

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You can do it. Head gasket is not bad,. You can do it in a few hours. I sent a pm I would be gald to help with the details. It will be easier by email. Have him drain the coolant, get the tank, seat, and exaust off. Disconnect compression release. Take off the coolant line off the front of the head. Remove the breather hoses on top of the valve cover. Remove the head stay. Remove the valve cover. Release the cam chain tension. You wind it up with a screwdriver, refer to manual. Remove the cams. I put a zip tie around the cam chain so it is easy to retrieve. The cams must be out before you can reach all the headbolts. Remove all the head bolts. Be VERY carefull to catch the littl crescent clip/key thingymebobbers that locate the big bearing by the cam gears when removing the cams. They are easy to drop down in the motor and hard to retrieve. Remove the head. Check the head gasket surfaces with a little parrelel or othe flat machined surface. I really doubt the head or cylinder is warped as these are substantial chucks of metal, but it is possible. At least use a vey good straight edge. You can lightly coat the head gasket with 3 bond if you want some insurance but it is messy. Do not use 3bond on the base gasket if you do take the cylinder off. Put her back together and torque per the manuel. The manuel has all the info you need to do this job. I hope this helps! ---Mike

Ohh! The manuel shows how to set the cam timing follow it, no big deal. Just do one step at a time.

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