800r eating coolant

[Concrete Mike]

I have an 07 xrs with 3500km on a skidoo rebuild. i replaced the pistons 600km ago as the were getting rattaly.it started leaking coolant from the rad cap so i tweaked the cap thinking it was loose then it started to burn the coolant.i tore the motor down and didn't see anything wrong with the base gasket or orings.put new gaskets in and it seemed fine for 150km and it starting to use coolant again.there is some presure in the coolant system but not like a typical blown head gasket. The coolant looks like mud.

Where else can the coolant come in contact with the combustion chamber?
Any ideas woulkd be great
Thanks Mike

 

[byeatts]

I have an 07 xrs with 3500km on a skidoo rebuild. i replaced the pistons 600km ago as the were getting rattaly.it started leaking coolant from the rad cap so i tweaked the cap thinking it was loose then it started to burn the coolant.i tore the motor down and didn't see anything wrong with the base gasket or orings.put new gaskets in and it seemed fine for 150km and it starting to use coolant again.there is some presure in the coolant system but not like a typical blown head gasket. The coolant looks like mud.

Where else can the coolant come in contact with the combustion chamber?
Any ideas woulkd be great
Thanks Mike

.O ring , Cracked cylinder , cracked head

 

[Concrete Mike]

so i pulled the head off and one oring was melted. when i ran a straight edge accross the aftermarket head one dome was recessed. the back side of the dome was worn, i turned it abit and all seems good

 

[byeatts]

so i pulled the head off and one oring was melted. when i ran a straight edge accross the aftermarket head one dome was recessed. the back side of the dome was worn, i turned it abit and all seems good

hmm the dome needs to be strong and seat before the outside of head seats?You using Vitron O rings?

 

[Concrete Mike]

just useing stock doo o-ring.i marked the dome to the head and when i torqed the plugs the dome didn't move.If it don't work this time the tabs that push on the dome must be worn and the head is junk. I guess the real ? is why would the domes have moved in the first place.there must be close to 4000miles on this head.

 

[dicey]

just useing stock doo o-ring.i marked the dome to the head and when i torqed the plugs the dome didn't move.If it don't work this time the tabs that push on the dome must be worn and the head is junk. I guess the real ? is why would the domes have moved in the first place.there must be close to 4000miles on this head.

i have had the same thing happen just shave the head housing a bit and buy a new dome. fwiw mine had about the same miles