2004 WR450 Coolant issue


5 replies to this topic
  • Lucas_wr450

Posted January 03, 2009 - 12:30 AM

#1

Hey everyone,

I've got a 04 Wr450 and after riding it the coolant heats up (obviously) and flows into the overflow tank, my problem is that it never flows back into the radiator, even after overnight cooling. I have changed the radiator cap and the line is clear, does anyone have any ideas whats wrong?

Cheers

Lucas

  • Birdy426

Posted January 03, 2009 - 12:39 AM

#2

Had a similar problem on my big bore 426 (444). It turned out to be a blown head gasket. Two things happened...first, when running, the water jackets were pressurized by the compression leaking into them, forcing more coolant out of the radiators than could be recovered, and second, the vacuum necessary to suck the coolant back into the radiators couldn't be generated, because the cooling system was vented into the cylinder thru the blown gasket.

Make sure that there are no vacuum leaks in the line that runs between the radiator and the catch tank (especially at the connection to the radiator), and then have the cooling system pressure checked.

  • Lucas_wr450

Posted January 03, 2009 - 01:06 AM

#3

i thought about the head gasket but there are no visible leaks anywhere and with the rad cap off there are no bubbles forming in the radiator, but i'll have to pressure check it.

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  • Birdy426

Posted January 03, 2009 - 09:52 AM

#4

i thought about the head gasket but there are no visible leaks anywhere and with the rad cap off there are no bubbles forming in the radiator, but i'll have to pressure check it.


Mine was the same way. The leak was a small one between the water jacket and cylinder at the rear of the head where the stud comes thru the boss on the barrel. No bubbles in the coolant (which I found odd), no water in the oil or oil in the water either, which wasn't so odd as it was a small leak into the combustion chamber on a fairly fresh engine rebuild.

My bike just started displaying the same symptoms again yesterday on a 100 mile desert loop. I'm wondering if the combination of big bore and hi-compression is a bit much for the gasket...

  • Thumper_Bloke

Posted January 03, 2009 - 04:28 PM

#5

I had a similar problem. I found that the long small clear hose had a small pinhole in it. I think pinched it once putting on the tank. Got a new hose, and all is good.

  • Lucas_wr450

Posted January 03, 2009 - 08:00 PM

#6

I might get some new hose tomorrow and hopefully that works, thanks for the help




 
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