honda bf 15a problems after impeller/thermostat install

[bclark1974]

I recently bought a 15hp Honda 4 stroke. It ran well but it wasn't peeing water the way I thought it should. So I bought an impeller rebuild kit along with a thermostat. I put them both in today and it peed water better then It did previously. During high rpms it stops pissing but I shrugged that off to not enough water intake from a garden hose. When I drop it back down to idling or just above idling it starts peeing again, after a few seconds, like i would expect it to. After about 10 mins of running the engine and checking temperature of the water as it came out, it seemed ok but could be better, and then the motor shuts off. The motor doesn't feel overly hot to touch so I start again. It starts right up but then a couple seconds later it shuts off again. It does this several times till eventually i gave up on starting and started looking into a possible clog in the manifold keeping it from peeing properly. I pull the manifold off and notice lots of corrosion, one of the reasons for replacing the thermostat, so I try to clean it up a little. I decided to give up for the night and come inside and post to see if anyone has anything to add or suggestions of why the engine would cut off and if the corrosion in the manifold would possibly make it **** somewhat funny. Any input would be greatly appreciated for this is my first outboard and could possibly getting over my head fast.

 

[Sea Rider]

Welcome to Iboats,

What usually do when suspect having internal salt, debris clogs is high pressure water jetting all internal water passages using a engine flush adapter conected to a garden hose that provides high water pressure. Must remove thermo from housinmg, place back housing and flush engine off for at least 5 minutes to free clogs. Buy a Honda flushing adapter to hook onto engine, muffs don't work well for this specific cleaning procedure. Run a wire, W40, carb spray cannula, thin plastic tie & wrap up/down through pee hole when jetting.

If previous owner, which you probably don't know about, was not a big fan of flushing engine specially when used at sea definitely will have narrowed water passages and salt clogs which are hard to remove by high water jetting. In most cases will need to tear cylinder head and all water lids and scrape all water passages mechanically for engine to cool properly as when out of tthe box.

Once all water passages are at least clog free, if engine continues to shut down could be a electrical related issue, electrical components internally heats up, shorts and shuts engine down, will need to test with tester all electrical components.

Happy Boating

 

[bclark1974]

Very helpful. Thank you