yz450f overflow problem

I put a new top end on my 04 yz450f and it wont stop leaking out the overflow. I tried a new radiator cap (didnt work) checked the oil for water no water. The only think i can figure is i didn't toque the head right and compressed gas is getting in the cooling passages.what do yins think?

After having run the engine and the system cools off and you open the radiator cap, what is the level? Is it still slightly above the core or not?

Its below the core after only a short ride.

Is the new radiator cap the same temperature cap as the old cap?


And what temperature cap are you running?


Did you use new head / cylinder gaskets?

The new radiator caps rated higher 1.6 and yeah all new gaskets

First off are you using at least 50/50 to prevent boil over or more antifreeze.

Yeah even tried engine ice

Yeah even tried engine ice

Yeah even tried engine ice

Yeah even tried engine ice


And did you flush out all the water mixture per the engine ice instructions ?  


Have you bleed the radiators for air?

I flushed out the system when I put the engine ice in how would Ya get any air out of the system and would that really cause that problem

Air purges itself, so it's a non-issue.  If the system is filled at the radiator, that's all you need to worry about as relates to that.


My question is, how did you torque the the head?

Didn't use a torque wrench to torque the head to spec so I figured that was the prob

Torque to spec, criss-cross pattern

Time for new head gasket and a torque wrench. Hopefully the head wasn't warped by whatever tightening method you used the first time.

I torqued it to spec runs great now .. Thanks for all yins help

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