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Oil in cooling system

Joined Apr 2005
55 Posts | 0+
Mobile Alabama
It appears I have oil getting into my cooling system. I noticed last week when checking the level (I use Evans) that there was a mysterious paste accumulating on the metal end of the radiator cap. I drained the coolant, cleaned off the mysterious paste, and hoped it would never come back. After an enduro this weekend (1st place 4 stroke B) :D the goo has returned. I guess it has to be oil, so where's the most obvious place for it to seep into the coolant? Other things to check for?

Thanks,
Dalton
 

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It does not have the typical look or consistancy of engine oil in a cooling system. I'm not really sure what it would look like with Evans though. I would have to think the characteristics would be the same. I think I would keep an eye on it for alittle while longer before any tear down. Keep wiping it off and notice if it subsides or gets worse, especially if there is no sign of coolant in the oil.

Some suspect places for oil contamination would be.
1) O-ring for the clutch cover.
2) Head gasket
3) possibly the cylinder sleeve seals
4) possibly the water pump seal and bearing
 
Yeah, head gasket is the wise money choice. the water pump seal would do it all the time so would allow the oil to mix cold, and look like oil floating on the coolant. the head gasket is the more likely after the hard work the engine did during an enduro. and when mixing hot the oil forms an emulsion like lathe fluid.
 
I'll replace the head gasket and see if that solves it.

Just out of curiosity, is the oil pressure higher than the water pressure? Otherwise, wouldn't I have water in the oil?

If I use Evans (Propylene Glycol) which is a zero pressure coolant, but I haven't modified the rad cap, is the water pressure the same as if I was using Ethylene Glycol?


Thanks for the replies,
Dalton
 
You should be running close to a zero pressure cooling system with the Evans, especially if you run a cooling fan.
 

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