Crf450r Head Gasket Nightmare

9/15/2019 3:32pm
Bought an 06 Crf450r that had the typical blown head gasket symptoms, white smoke, coolant filling crankcase, pressuring cooling system with exhuast, etc. Pull head and replace headgasket, runs great, no more smoke, no more coolant in oil, but then i notice from the back left portion of the cylinder it is leaking oil out of the headgasket, not coolant, but oil and oil alone. I have never had a headgasket leak oil. I assume slight warpage and pulled head and cylinder again and resurfaced them, (not with a machine, but with glass pane and varying grits of sandpaper adhered to it. I marked both surfaces with marker along the way to make sure it was getting wearing away to a uniform finish, I could not fit a .002 feeler gauge between the cylinder and head anywhere when I was finished, I installed yet ANOTHER new headgasket with copper spray this time to ensure no leak......and hours of labor later, it still leaks very slowly from the same spot. Anyone had this happen before?? Im maybe thinking the oil passages are overpressurized somehow, maybe a clog or something causing it to back up and leak out.....just wondering if anyone has delt with this before. I am so sick of f**king with it.
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9/15/2019 6:22pm
Do you have the steel pilot sleeves installed in the top of the cylinder? I’ve seen that cause it before.
kb228
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Mansfield, OH US
9/16/2019 5:10am
The back left would be where your timing chain is right? Theres no coolant there.

Something is still warped or your gaskets are defective.

Another issue could be..when you resurfaced the parts, they were warped in a manner where the parts didnt sit on the glass perfectly perpendicular to the centerline of the cylinder bore. So one surface could be 1/2 degree off one way and the other 1/2 degree off the other way. You may not be able to get a feeler gauge in there but there also may not be enough clamping pressure due to them not being flat AND square. That especially can be the case around the timing chain area. Theres usually only a couple small bolts clamping there. The big head bolts arent close - relatively speaking.

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