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Coolant in crank/cylinder!?

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Last weekend I was out riding my bike (2005 crf250x) and it cut out on me while I was cruising 5th gear down the road. Got it back home and tore into it, and there was coolant sitting on my piston, and coolant in my crankcase oil. We figured it was the head and cylinder gasket due to a little damage in them, but after replacement, there is still coolant getting into my crank oil. No more water is getting into my cylinder, and there doesn't seem to be any noticeable coolant loss out of the radiator, and the bike runs fine. I have changed the oil twice now after running it for a few minutes each time, but the oil is still milky after two changes... I did a pressure test on the coolant system, and it has held 10 psi for two days now....So I guess my question is could there be a crack appearing when the engine heats up, or could there still be residual coolant in the crank from the head and cylinder basket going out?

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Last weekend I was out riding my bike (2005 crf250x) and it cut out on me while I was cruising 5th gear down the road. Got it back home and tore into it, and there was coolant sitting on my piston, and coolant in my crankcase oil. We figured it was the head and cylinder gasket due to a little damage in them, but after replacement, there is still coolant getting into my crank oil. No more water is getting into my cylinder, and there doesn't seem to be any noticeable coolant loss out of the radiator, and the bike runs fine. I have changed the oil twice now after running it for a few minutes each time, but the oil is still milky after two changes... I did a pressure test on the coolant system, and it has held 10 psi for two days now....So I guess my question is could there be a crack appearing when the engine heats up, or could there still be residual coolant in the crank from the head and cylinder basket going out?

I'd go with the theory of residual coolant. Has to be if your system is holding pressure, unless it only leaks when running. I've had that with radiators but not the engine. I think I'd but some cheap oil, and keep flushing warm, shouldn't take too many?

Mike

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I dont know that bike/engine specifically, but is there a chance it could be the water pump seal?  It could be any of the things you mentioned at the end of your post also thou.

 

Also if it were me I would probably try pressure testing with more than 10psi, if the rad cap is a 1.6 bar which seems pretty common, then that equates to about 23psi.  Thou if it can hold 10psi perfectly for 2 days then more pressure may not show anything either.

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I dont know that bike/engine specifically, but is there a chance it could be the water pump seal?  It could be any of the things you mentioned at the end of your post also thou.

 

Also if it were me I would probably try pressure testing with more than 10psi, if the rad cap is a 1.6 bar which seems pretty common, then that equates to about 23psi.  Thou if it can hold 10psi perfectly for 2 days then more pressure may not show anything either.

Yes, Mylers if I remember, suggests 20#. I think most water pumps leak to the outside, through a weep hole.

Mike

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Hey thanks. Yeah my weep hole is dry, so I think that seal is good... and thats good to know. I wasnt sure how many psi i dared go, so i will try that. I think I will go get some cheap oil like you say and change it a few more times first..thanks again

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The water pump is driven by the crank via some gears inside the clutch cavity.  As JD said two seals on the water pump shaft; one keeps water in the pump and the other keeps tranny oil in the clutch cavity.  The space between the two seals is open to the weep hole. If the pump seal fails coolant drains out the weep hole, if the other seal fails tranny oil could drain out the weep hole. This is good engineering design and typical Honda, but not typical on some other motorcycle brands.

 

So the only likely places that coolant could get into the engine oil are from the cylinder/head and their associated gaskets, and it is usually the gaskets rather than a crack leak in the cylinder or head. Coolant could get into the tranny oil via the O ring on the coolant transfer passage between the right side cover and the right crankcase.

 

It doesn't take much water to froth up oil and thickening it so it doesn't drain well, so the oil change didn't drain all of the oil/water.  Couple that with the oil that doesn't drain because it is in oil passages and it may take a few oil changes to get it all out.

Edited by Chuck.
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Chuck is right on with his diagnosis.  Water pump replacement should be a regular maintenance item for both the X and R as they do wear out over time.  Not uncommon at all and not the end of the world.  And, even if it isn't a gasket leak on the top end, there is nothing wrong with giving the bike a little love and replacing the top end.  Both the top end and water pump kit are fairly easy garage projects depending on your skill with a wrench.  If you have a manual and some time, this can be done in a day for both of the items.

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I ran a few more quarts of oil through the crank case, and the oil finally cleared up, so I think there was just residual coolant in there. And for the top end, I think it is still in pretty good shape. The previous owner changed it not too long ago, and there are still visible honing marks in the cylinder and the rings still look good. But I will look into the water pump kit.

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I ran a few more quarts of oil through the crank case, and the oil finally cleared up, so I think there was just residual coolant in there. And for the top end, I think it is still in pretty good shape. The previous owner changed it not too long ago, and there are still visible honing marks in the cylinder and the rings still look good. But I will look into the water pump kit.

What ever became of it? If i may ask.

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