HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
msliker22

07 yz450f head gasket difficulty

6 posts in this topic

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

Share this post


Link to post
Share on other sites

  :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. 

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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-motor.eu/eu/services/owner-manuals/index.aspx

http://www.yamahaownershandbook.com.au/?r=0

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0