Honda b100 pre 97 1200000 serial number

Hey guys. Pretty new to boating and in need of advice. I bought a b100 and am having a hell of a time getting water to the top. New impeller checked and double checked for damage. Can’t find any blockages. Air will move through all jackets just fine. I took the intake manifold off and everything looked ok other than it had no stat. And everything seemed to be working ok until a road trip. I’m getting tired of pulling out my hair.

So the road trip was with boat on trailer, outboard on transom?
Mucho bouncing up and down?
I see that these old gals have a LOT of "erosion" take place in the metal where the seal holds the water tube in the bottom of the block.
Check out items 6, 7 and 18 in link below. When upper #7 gets worn and deformed, the tube is then free to move and grind away at the aluminum port it sits in from the considerable vibrations this engine produces. This also wears the tube itself and, as time goes by, the connection ends up leaking pretty badly and less and less water makes it into the engine block.

https://www.boats.net/catalog/honda...p/bf100-la-pre-1997/water-pump-vertical-shaft

It's just as likely though that all the bouncing caused an old piece of broken off impeller arm to dislodge from its resting place and is now blocking water flow somewhere inside the block. Since you can't see inside the block, this might be difficult to remedy. Blowing high pressure compressed air might do it but high pressure water would be more effective.

Yeah road trip was outboard on transom. Boat on trailer. I’m wondering if it’s not the water tube going up as it’s pretty hard to tell when it’s running. I’ll check that out for sure.

It's always a good idea to check that area on these old outboards. I have built that area back up and re-formed the seal and tube seat area with epoxy. As far as I know those have held up well for years now.

If you find that you need to do that, drill some very small diameter, very shallow holes in the metal to serve as anchor points. The tube seat doesn't need to be factory perfect. You have to shape it and get it as close as you can.

Good luck.

I will check that out! Thanks

Try placing garden hose directly to water tube,pull thermostat housing off,start engine, water should gush out of housing if everything is intact

Can’t start with stat housing off. Stat housing, intake manifold and exhaust manifold are all one casting