07 yz450f head gasket difficulty


5 replies to this topic
  • msliker22

Posted June 02, 2014 - 06:01 PM

#1

I'm blowing coolent out of my radiator cap after I run it up an down the road for about 2 min I was told to replace the head gasket how hard is that to do on this bike this is my first 4 stroke

  • ekulb14

Posted June 02, 2014 - 06:49 PM

#2

  :jawdrop:  ok so umm wait, your leaking coolant out of the radiator cap after it builds pressure. just replace the readiator cap im guessing the o ring just went bad. there is no need to replace the head gasket unless im not reading your post right. 



  • dirtbeater

Posted June 03, 2014 - 06:05 PM

#3

I believe the theory behind this is the engine explosion is pushing air into the coolant system. I am not too familiar with four strokes either. I do know a smoker is much easier to work on the top end. You would have to pull the valve cover, cams and cam chain. I also believe the head gasket is a one use thing. I do know you should replace your cam chain since you are there already.

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  • Mike in OK

Posted June 03, 2014 - 06:13 PM

#4

If you had a blown head gasket you would likely be getting coolant in your engine oil. Try the simple thing first, get a new radiator cap.

  • grayracer513

Posted June 04, 2014 - 06:53 AM

#5

If you had a blown head gasket you would likely be getting coolant in your engine oil. .

 

That is not necessarily true at all.  It may simply take more than 16 psi to push past the gasket.  They quite often leak combustion pressure into the cooling system without contaminating the oil. 

 

BTW, this is about the fourth thread this gentleman has put up about this same problem, and he's gotten the same answer each time; head gasket.  The circulation should be checked to see if the water pump is moving water, but if he gets coolant blowing out of a cold engine in 3 minutes of running up and down a street, he's either got the weakest radiator cap around, or a head gasket.

 

 

 I was told to replace the head gasket how hard is that to do on this bike this is my first 4 stroke

 

Complicated, but not too difficult.  On a 1-10 scale, it's about a 7.5 for first timers. Get a manual:

 

http://www.yamaha-mo...uals/index.aspx

http://www.yamahaown...ook.com.au/?r=0



  • 72degrees

Posted June 04, 2014 - 07:14 AM

#6

That is not necessarily true at all.  It may simply take more than 16 psi to push past the gasket.  They quite often leak combustion pressure into the cooling system without contaminating the oil. 

 

 

My Gilera Nordwest with FPM  604cc big bore conversion gave great problems with the head gasket as the mating surfaces around the coolant passages were left so narrow in the 102mm cylinder. The kit came with a solid copper head gasket rather than the OEM composition type but even after careful re-torqueing after a couple of minutes running it would start to pressurise the cooling system after a while.

 

That was very dependent on how much you gave it the beans. Ride it relatively gently and it was fine. Lots of throttle at low revs and the radiator expansion tank would quickly fill up. Just once I found a few drops of coolant in the oil. As it was only being used for speed hill climbs,  A little radweld in the system stopped that and I resorted to using a bicycle pump on the expansion chamber breather once cold after each run to force the coolant back where it belonged. I managed to finish the season that way but I never cured it 100% and many other Nordwest tuners using the same kit had the same problem.

 

The best I got it was by changing to a new known un-warped head, fitting new studs that hadn't been stretched and using a bit more torque than standard on those as advised by Luigi Frigerio who produced the kits. Even then, one run up the 5 Km hill on the IoM TT course had it puking coolant again.


Edited by 72degrees, June 04, 2014 - 07:16 AM.






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