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phobs

coolant coming out of spark plug drain hole

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I recently noticed that when i start my yz450 up and let it idle to warm up, that there are a few drops of coolant that come out of the spark plug drain hole. if i ride the bike around the block a few times, enough coolant will come out, that it will run down the side of the cover, and there will be a small puddle of coolant on the top of the engine case. it doesnt seem to drip all the time, mostly notice it when i start the bike up. any ideas of what may be causing this? thanks.

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I recently noticed that when i start my yz450 up and let it idle to warm up, that there are a few drops of coolant that come out of the spark plug drain hole. if i ride the bike around the block a few times, enough coolant will come out, that it will run down the side of the cover, and there will be a small puddle of coolant on the top of the engine case. it doesnt seem to drip all the time, mostly notice it when i start the bike up. any ideas of what may be causing this? thanks.

If you did blow the head gasket I wouldn't recommend riding it a lot. Some coolant could have gotten in the oil

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The kids right. The oil will foam up from the coolant and will cause more damage then you would think. Just so that you know the loss of the cooling system will completly destroy the engine if you keep riding it (crank, rings, piston could seize, etc) just fyi. Sorry, forgot to mention that earlier.

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What possible path could coolant follow from a blown head gasket to the spark plug drain hole?!??

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What possible path could coolant follow from a blown head gasket to the spark plug drain hole?!??

Exactly.... I think my guess would be cracked head. :thumbsup:

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i know that there is no damage done to the motor. a few weeks ago i rode at the dunes, and noticed that the waterpump was leaking. checked the radiator and it was very low. so filled it back up and went home. tore the entire top end down to see if any damage had been done. only thing wrong was the valves were out of spec, and i also replaced the waterpump seals. put the motor all together and now it has the coolant leaking from the spark plug drain hole. it never leaked from there before. even while i was at the dunes. so maybe i just need a new head gasket? i dont think that the head got cracked, but maybe it did. also, when i got back from the dunes, i changed my oil. and there was absolutely no coolant in the oil. everything looked perfectly normal. any ideas? thanks for all the help already.

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I don't see how coolant will get in to the spark plug hole from a blown head gasket. The head and cylinder are mated together below this. A cracked casting would be a possibility. Have you tried pressurizing the coolant system to see if you can see antifreeze coming out? That is a weird problem. How much coolant comes out of the spark plug hole?

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i am wondering if the sleeve that is in the head itself somehow has come loose and is causing the coolant to leak. by the sleeve, i mean the actual tunnel that is the spark plug drain hole. it looks like that is a sleeve that is pressed into the head. maybe that somehow has come loose and it seems as if the water passages in the head run right past this sleeve, that some of the coolant is seeping by it and coming thru the exit to the spark plug drain hole. there is enough coolant coming out to have a small puddle on top of the engine case when riding it around the block a few times. probably half a teaspoon worth.

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