Honda BF15 Water Path & Cooling

[Paul in Beaufort]

I have a 1997 Honda BF15 with a cooling issue. I recently acquired this motor and when I started it there was no water coming from the indicator port ("pee hole"). I checked the impeller and except for a tiny chip on one of the vanes it looked okay. (I've ordered a new one anyhow.) I cleaned the inlet ports on the foot and the passage seems clear into the water pump housing. I removed the thermostat cover and started the engine and there was no water flowing.

I have a couple of questions. I cannot see where the outlet hose from the pump goes. Does it go to the block or is there a hose somewhere that I cannot see that takes it elsewhere? In other words, where does the water go when it leaves the pump? Does the thermostat control flow from upstream or downstream of the water jacket? And lastly, short of taking the powerhead apart, how do you check and clear the tube from the pump up into the top?

I have poured water down the hose from the thermostat and that seems to be the outlet which exits with the exhaust through the prop so even if water were getting to that point it would keep flowing....but it's not.

Any help or information would be helpful.

Thanks,
Paul

 

[Sea Rider]

Re: Honda BF15 Water Path & Cooling

Paul, some issues to check :

Remove tail, place it on a bucket filled with water, insert an appropriate drill machine head onto engine's upper shaft. Turn on drill check the amount of water flowing through upper WP grommet. If pressure is low, replace impeller could be worn, dried and hardened, that's assuming other WP parts are not heavily scratched or severely worn. If so, replace ccomplete WP kit.

Insert a hose into lower water tube, the one that inserts into WP grommet, remove thermo and screw thmo lid back onto powerhead, open faucett, check if pee hole pees. If with a light internal water passage clog, water pressure should remove it.

If not, will neeed to remove power head off pan and open all water side lids including cylinder head and mechanically remove all saly crusts and layers formed there if previous owner happens to constantly used his engine on salt water and not knowing a thing about flushing it with fresh water at each outing. Seems a typical salt clogged pandora box...

When all water pasages are visible squirt an overdose of pure vinegar, let soak into each passage, with a shushi wooden or plastic stick go through each passage and scrape crust and salt layers away. Repeat with vinegar squirts while doing so. Don't use a metal or sharp instrument to do so, could end scratching water passagess severely and salt will enevitably will start to be formed there. Good luck on your findings...

BTW, will need to buy new thmo, water lids, pan and cylinder head gaskets.

Happy Boating

 

[HaMm3r]

Re: Honda BF15 Water Path & Cooling

Question...are you running it on muffs or in a barrel? A lot of times muffs don't provide adequate water pressure to prime the pump. If using muffs, try squeezing them tightly against the intake ports with your hands. Just be careful you don't accidentally put the motor in gear.

If you're sure water supply is adequate I would tape off all the intakes on the lower unit and block the telltale (pee hole). Then remove the thermostat cover and fill the entire cooling system with vinegar and let soak for a few hours. Then remove the tape/block, replace the stat cover and try running it again.

 

[isaksp00]

Re: Honda BF15 Water Path & Cooling

On my Honda 8HP, I have had problems putting the tail back on and ensuring the water tube actually goes into the grommet at the top of the pump housing - it is a bit tough to line up as you replace the lower unit. If you find that the pump is sending a good flow when you test it in a bucket (as Luis suggested) and also that water from a hose up the tube flows well through the pee hole, it may be that they didn't line up when you put the LU back.