Where could the coolant be going?


10 replies to this topic
  • Dan_187

Posted July 29, 2008 - 10:06 PM

#1

I tore apart my 06 yz450 to the piston. it is sucking coolant somewhere somehow, the coolant is not in the oil so it is getting into the combustion chamber, it is being blown out the overflow tube as white vapor smoke. Its loosing a lot of coolant not just a bit it will be empty if i dont retop it

I'm thinking its faulty gaskets, either the head gasket or the base cylinder gasket. Could this be the case??

  • KJ790

Posted July 30, 2008 - 03:32 AM

#2

The most common way that coolant gets into the combustion chamber is a bad head gasket. A cracked head can also do it, but that is rare (especially for these bikes). Coolant in the combustion chamber also often causes white smoke to come out of the exhaust when the engine is running.

  • grayracer513

Posted July 30, 2008 - 07:45 AM

#3

The base gasket won't do it, because that would leak either externally, which you could see evidence of, or internally, which would pollute your oil, as we have already discussed.

Your culprit is probably either the head gasket, as KJ says, and/or the radiator cap.

  • lilyamaharacer9

Posted July 30, 2008 - 07:49 AM

#4

The most common way that coolant gets into the combustion chamber is a bad head gasket. A cracked head can also do it, but that is rare (especially for these bikes). Coolant in the combustion chamber also often causes white smoke to come out of the exhaust when the engine is running.


I dont think that it could be the head gasket because then he would have "milky" oil, and that would not make it come out the overflow tube.

Im stumped on this one the only time that ive ever seen coolant coming out the overflow that is white vapor, is when my bike overheats, but you can see coolant come out too not just the white vapor.

  • mkporn

Posted July 30, 2008 - 07:58 AM

#5

I dont think that it could be the head gasket because then he would have "milky" oil, and that would not make it come out the overflow tube.

Im stumped on this one the only time that ive ever seen coolant coming out the overflow that is white vapor, is when my bike overheats, but you can see coolant come out too not just the white vapor.


you can smoke a head gasket and not have water in your oil. infact this is very common with new 4 strokes. take a peek at the head gasket next time you have one in your hands. if it goes it is way more likely that it will be at the water jacket then any other place.........


that said, if the gasket is bad enough to leak just sitting there not running you have the possibility of coolant running into the cylinder and leaking by the rings into the crank case...

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  • matt4x4

Posted July 30, 2008 - 08:07 AM

#6

if the head gasket goes between the water jacket and the inside of the piston chamber, it'll bur it off in the cylinder upon combustion and nothing will get to your oil - you would also see your piston cleaned off abnormally in a spot or two - not your normal looking evenly discolored piston.

  • grayracer513

Posted July 30, 2008 - 08:17 AM

#7

you can smoke a head gasket and not have water in your oil.


if the head gasket goes between the water jacket and the inside of the piston chamber, it'll bur it off in the cylinder upon combustion and nothing will get to your oil - you would also see your piston cleaned off abnormally in a spot or two - not your normal looking evenly discolored piston.

True, in fact a head gasket leaking from inadequate torque may not even show any damage. For coolant to leak to the crankcase from a head gasket, it has to leak along the left of the combustion chamber, and into the cam chain tower. If it leaks on the other 3 sides instead, there's no oil contamination.

The point Matt makes about carbon is also a good one. Cylinders that have been chewing water will be uncommonly clean because of it.

  • yamaha542

Posted July 30, 2008 - 08:43 AM

#8

Replace the head gasket and check head bolts for stretch, easy fix, not a whole lot of things it could be.

  • Dan_187

Posted July 30, 2008 - 07:20 PM

#9

I'm going to put everything back together with fresh gaskets and properly torqued bolts, hopefully it fixes the problems. I took my cylinder head to the shop they couldnt see any wear or cracks that could have caused a problem like this so we will see what happens

  • mkporn

Posted August 14, 2008 - 07:40 PM

#10

True, in fact a head gasket leaking from inadequate torque may not even show any damage. For coolant to leak to the crankcase from a head gasket, it has to leak along the left of the combustion chamber, and into the cam chain tower. If it leaks on the other 3 sides instead, there's no oil contamination.

The point Matt makes about carbon is also a good one. Cylinders that have been chewing water will be uncommonly clean because of it.


Known as steam cleaning and actually a common practice to induce small amounts into a cylinger to effectively burn off carbon....:)

  • Dan_187

Posted August 15, 2008 - 12:09 PM

#11

put a new piston in it, honed the cylinder, new base and head gaskets and a timing chain for good measure and guess what?? NO MORE COOLANT BURNING :) :D :worthy: :ride: :banghead: :banghead: :banghead: :banghead: :banghead: :banghead: :banghead: :ride: :ride:


also, i always had that black sludge drip a few drops out of the crankcase vent tube and now it doesnt drip anymore either





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