yz450f overflow problem

14 replies to this topic
  • Bigfoot0518

Posted June 25, 2016 - 08:21 AM


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?

  • Trailryder42

Posted June 25, 2016 - 08:31 AM


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?

  • Bigfoot0518

Posted June 25, 2016 - 08:39 AM


Its below the core after only a short ride.

  • Trailryder42

Posted June 25, 2016 - 12:04 PM


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?

  • Bigfoot0518

Posted June 25, 2016 - 12:56 PM


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

  • stevethe

Posted June 25, 2016 - 06:59 PM


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

  • Bigfoot0518

Posted June 25, 2016 - 07:25 PM


Yeah even tried engine ice
Yeah even tried engine ice

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  • Krannie McKranface

Posted June 25, 2016 - 08:42 PM


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?

  • Bigfoot0518

Posted June 26, 2016 - 04:13 AM


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

  • grayracer513

Posted June 26, 2016 - 06:47 AM


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?

  • Bigfoot0518

Posted June 26, 2016 - 07:26 AM


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

  • motohead13

Posted June 26, 2016 - 09:18 AM


Torque to spec, criss-cross pattern

  • damnbiker94

Posted June 26, 2016 - 10:20 AM


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

  • grayracer513

Posted June 27, 2016 - 05:50 AM


Yes, and the torque procedure is more complicated than simply running them up to a number, too. 


Read: http://www.thumperta...ead-tightening/


Torque pattern sequence is:


1) Left rear

2) Right front

3) Left front

4) Right rear

  • Bigfoot0518

Posted June 27, 2016 - 05:06 PM


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

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