Honda BF8 Cooling Problem

[wake_rider]

Hey All, I'm new here, new to owning a boat. But I'm having some problems with my motor.

I've just recently aquired a small boat with a Honda BF8 motor. I'm not sure what year it is, it's newer, on the cover it says it meets 2006 epa standards so I assume it's at least 2006.

Anyways, The engine starts ok, but no water flows from the tell-tale. I can feel air blowing out of it, but no water. If I connect a hose-adapter water flows out of it fine, as well as flowing out the intake and the holes around it.

The screen is clean and in good shape, however when I took it off I found a small pile of black rubber bits that were trapped on the inside. They look like they were some sort of flap or somthing that got ripped up. So I flushed the engine out with a hose again, replaced the screen and tried it again in the water. Still no flow....

Anyone have any ideas?

 

[wake_rider]

Re: Honda BF8 Cooling Problem

Ok found the problem, I decided to take the motor apart and hope I could figure out what the problem was and how to put it all back together.

Anyways it seems the rubber bits I found were the fins on the water pump impeller.

So the solution is to get a new impeller.




However I still have a question to somthing I don't understand....

in the 2 pictures below it shows the drive shaft without the impeller on it, and just the impeller on the ground... what I don't get is... is there a peice missing there? It just slides down the shaft into position, but nothing seems to lock it from spinning freely. So whats to stop it from just not moving while the shaft spins inside it? The shaft has a notch on it, and the impeller has a groove down the inside but there was no pin or connector that I saw, no mechanical way of locking it to the drive shaft to make it spin while under load.

Did I miss somthing? is somthing missing?

 

[gss036]

Re: Honda BF8 Cooling Problem

Looks like you are missing the little square key way keeper, about 3/16 X 3/4". That is why the impeller has a grove in it.
Also looks like you unscrewed the jam nut all the way down the threads on the shifting rod. You might have trouble getting it to shift correctly unless you marked the spot someway.

 

[Mas]

Re: Honda BF8 Cooling Problem

You also may want to remove the thermostat and "back flush" the cooling passages with a garden hose to see if any bits can be dislodged.

MAS

 

[wake_rider]

Re: Honda BF8 Cooling Problem

Looks like you are missing the little square key way keeper, about 3/16 X 3/4". That is why the impeller has a grove in it.
Also looks like you unscrewed the jam nut all the way down the threads on the shifting rod. You might have trouble getting it to shift correctly unless you marked the spot someway.

Thank you, that is exactly the info I was lookin for. I noticed the impeller housing is cracked with a little hole so I'm just going get a new kit which looks like it comes with key way.

I didn't end up marking the shifting rod because they we're just butted right together when I unscrewed them. So I think I'm safe that way.

You also may want to remove the thermostat and "back flush" the cooling passages with a garden hose to see if any bits can be dislodged.

How hard is that to do? I have no experience with outboard motors.

 

[gss036]

Re: Honda BF8 Cooling Problem

You will need to remember where the LONG nut was positioned, no they were not just butted together. The long nut is used for adjustment of the shift rod and the short/small nut simply is a jam nut to lock it into place. At least it accessible from the outside of the leg when your engine is place in reverse.
You are not going to hurt the engine flushing it, use whatever water pressure you have.

 

[wake_rider]

Re: Honda BF8 Cooling Problem

I wasn't too worried about the pressure, i was more wondering about where the thermostat was... I'm not sure where it is exactly or how hard it is to get to.

If it's fairly simple to get at and remove to flush out I'll tackle it, otherwize im hoping my hose attachment would do the trick at removing and debris.

 

[gss036]

Re: Honda BF8 Cooling Problem

My Honda had the stat on top port side, rear part of then engine. Should be a couple of 10 MM nuts and a gasket. Really simple job.
Must be as I did mine a couple om times ;-).

 

[wake_rider]

Re: Honda BF8 Cooling Problem

ok so i finally got a new impeller....

it seems that you're supposed to bend the little rubber fins to fit in the housing, now logic tells me that you bend them backwards so they trail behind as it spins, but I could also see it working if they were bent forward to cup the water.

but i'm not sure so here I am again asking the advice of somone who knows

 

[pvanv]

Re: Honda BF8 Cooling Problem

They will take the proper set when running, regardless of how you install them. They do trail, not cup.