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Honda 8hp Bf8 Water Getting into the Motor Oil??? Help! Update....

D

dillon

Member
OK, new head gasket and O-ring inbetween block and head. I had the lower unit & tower off and ran a plastic hose line of water through the motor water intake for about an hour, (without the motor running) water was coming out of the exhaust and water hole check, after an hour no water got into the oil. I then ran the motor shortly, no water in oil. Then ran it till it warmed up, To make a long story short it looks like after the motor warms up and the thermostat opens and the water goes through all of its paths water gets into the oil, Can this narrow down the Problem as to where the water is coming from?? Starts on 1st pull and runs great. Its an 8hp BACL-1001299, I beleive its a 1991 model. I do have a Honda shop manual coming but don't have it yet, the seloc manual isn't much help, it even said you could pull the oil pan without pullin the powerhead but by looking at it I don't think so, (solid metal below the oil pan).. it would be nice to see a diagram of the water travel path. Just not to familiar with these 4 stroke motors, have always had 2 stroke's. Thanks for any input on this.
 
My opinion is that you may have a cracked cylinder head. Here's why I say that:

With the thermostat closed, water entering the engine circulates through the engine block via the water jackets surrounding each cylinder. Water is blocked from entering the cylinder head but is allowed to enter the intake manifold and exit the engine through the exhaust and water check tube via a "bypass" circuit.

When the thermostat opens, water is then directed through the cylinder head and from the head, most is directed out the exhaust. Flow through the bypass circuit continues to supply some flow to the intake manifold and exits there through the water check tube.

So, water is flowing through all parts of the system when the thermostat is open and is flowing through all parts of the system EXCEPT the head when the Tstat is closed.

Since you have determined that the leakage takes place ONLY after the thermostat is OPEN, then it stands to reason that the leak is in the head. Where exactly in the head would probably only be detected by removing the head and performing a pressure check.

You sound like you aren't afraid to dig in and problem solve so you may be able to figure out a way to seal the head and introduce slightly pressurized water through the thermostat inlet and find where it's leaking.

Another possibility;

Did you use a straight edge to check the head and the block for warping when you replaced the head gasket? Even with a new gasket, if one or both is warped bad enough it could still leak at the interface.

Those are my wild guesses. I hope the solution turns out to be simple and inexpensive.
 
I would have to answer that question by saying ANYTHING is possible. But, and remember, it's just MY opinion, I don't think so. Others may disagree and I would be interested in hearing how that could happen. I've given you my best guess and, without some testing, that's all it is...a guess.

Now, what about the question I asked you? Did you check your block and head for flatness?
 
yes, on glass. I tore it down, block looked very good, looks like the problem might have been the oil dip stick holder gasket, is this common? thx
 
It would not make any difference if the thermostat was open or closed. The dipstick fixture leaking should probably cause a leak at all times but, anything being possible, I guess it could occur with the engine hot and not when it was cold.

So you KNOW that was it or it just stopped? Or haven't you tried it again?
 
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