BF20D Honda cooling problem

[Goldi]

We are having issues with the cooling system on our engine! There is supposed to be a pee stream out of the back of the engine, obviously cool water comes in, warm(ish) water comes out..but theres no sign of any water coming out, so presumably none coming jn either? So far ive been able to scrub around the grate over the inlet that draws water in, my initial thought was there must be a blockage, nithing changed, I've not examined anything internally yet. Done a bit of resesrch online, a few articles say to take the engine out the water and stick it in a bucket of clean water.  Which isn't really something i want to do right away, also oretty sure that wouldnt fix the issue. Keen for advice and aby relevant resources or explanations, engines really arent something im confident with, please assume i know nothing! 

[frangar]

I’m no outboard expert but my first thought with any raw water cooling would be to check the water pump impeller. 

[magnetman]

This is a common problem with Honda. This is just an indicator not the full flow of cooling water. 

 

Rod it with a cable tie or a piece of wire.

It is usually just a bit of debris or scale buildup.

I mean clean out the exit hole where the 'tell tale' usually flows from. There isn't much pressure pushing water out of there so even minor blockages can stop it. 

 

 

Most of the cooling water exists through the exhaust 

 

 

 

(this isn't the same engine but the scheme will be generally similar)

Edited June 8, 2023 by magnetman

[Tony Brooks]

What Magnetman said. We had it all the time on our Merc. 8/9 hp hire outboards. Usually poking the tell tail hole with a bit of welding rod sorted it, especially if you did it with the engine running.

 

Having said that it could still be an impeller problem and that almost certainly means splitting the leg just above the prop and on rare occasions we had the odd one that bunged up some waterways formed by groves in the engine casting and the bottom "pan", but that may be a Mercury design feature. I have also had similar caused by an excess of gasket goo.

[Mad Harold]

The tell tale on most outboards is a rubber tube.

Best not to poke it with wire, but use a length of plastic strimmer cord.

[Alan de Enfield]

20 hours ago, Goldi said:

We are having issues with the cooling system on our engine! There is supposed to be a pee stream out of the back of the engine, obviously cool water comes in, warm(ish) water comes out..but theres no sign of any water coming out, so presumably none coming jn either? So far ive been able to scrub around the grate over the inlet that draws water in, my initial thought was there must be a blockage, nithing changed, I've not examined anything internally yet. Done a bit of resesrch online, a few articles say to take the engine out the water and stick it in a bucket of clean water.  Which isn't really something i want to do right away, also oretty sure that wouldnt fix the issue. Keen for advice and aby relevant resources or explanations, engines really arent something im confident with, please assume i know nothing! 

 

Here is the manual for your engine,

NEVER use  piece of wire to 'rod out' a P-pipe.  will punture the pipe somewhere inside.

 

If you have run the engine out of the water you could / will ave damaged the pump / impellor and it will need replacing.They should be replaced every year anyway.

 

I have the same engine on my tender.

 

 

 

 

BF20 Manual.pdf

[rusty69]

4 minutes ago, Alan de Enfield said:

 

Here is the manual for your engine,

NEVER use  piece of wire to 'rod out' a P-pipe.  will punture the pipe somewhere inside.

 

If you have run the engine out of the water you could / will ave damaged the pump / impellor and it will need replacing.They should be replaced every year anyway.

 

I have the same engine on my tender.

 

 

 

 

BF20 Manual.pdf 1 MB · 0 downloads

I think a bf20 is a bit bigger than your 2hp. 

 

 

[Alan de Enfield]

2 minutes ago, rusty69 said:

I think a bf20 is a bit bigger than your 2hp. 

 

 

 

The BF20 manual I attached to the post says it is 2hp !

 

(see page 37)

Edited June 9, 2023 by Alan de Enfield

[magnetman]

Yes the BF20D is a 20hp outboard. 

 

I have s BF10 and a BF2 . For some reason on the older outboards honda added an extra zero so the BF2 had 20 written on it and the old style BF10 had 100 written on it. 

 

 

 

 

OP outboard is BF20D

 

 

[Alan de Enfield]

1 minute ago, magnetman said:

Yes the BF20D is a 20hp outboard. 

 

I have s BF10 and a BF2 . For some reason on the older outboards honda added an extra zero so the BF2 had 20 written on it and the old style BF10 had 100 written on it. 

 

 

 

 

 

Fairy snuff - That confusing when I have a BF20 manual for a 2hp engine,

[rusty69]

2 minutes ago, Alan de Enfield said:

 

The BF20 manual I attached to the post says it is 2hp !

 

(see page 37)

Yeah, sorry. I meant bf20d as in ops title. 

 

 

[magnetman]

5 minutes ago, Alan de Enfield said:

 

Fairy snuff - That confusing when I have a BF20 manual for a 2hp engine,

 

It is odd that they added an extra zero. My silver cased BF2, which is same engine as yours, just has 2 written on it. 

 

Of course back in the day when they added the zero the range of outboards was 2, 5, 7.5 and 10hp. Nothing bigger from Honda in the early days to get confused about but now there is a 20, a 50, a 75 and a 100hp outboard in their range so the extra zero doesn't work. 

 

 

 

 

[rusty69]

10 minutes ago, magnetman said:

 

It is odd that they added an extra zero. My silver cased BF2, which is same engine as yours, just has 2 written on it. 

 

I have the silver BF2 as well. Changing the impeller on this engine is pretty straightfrowards. I've managed it at least once in 20 years.

[magnetman]

Yes it is an interesting design that one. The block is air cooled but it cools the exhaust with water. If the impeller goes the engine can still be run alright but not flat out. The newer versions are air cooled only but noisier. 

 

There are no cooling channels in the powerhead itself on the BF2. 

 

 

[Tacet]

45 minutes ago, magnetman said:

Of course back in the day when they added the zero the range of outboards was 2, 5, 7.5 and 10hp. Nothing bigger from Honda in the early days to get confused about but now..

 

 

 

 

In the old days, there was only the BF75 - and that is a new and wonderful thing compared to its competition.

[David Mack]

BF20D manual

https://cf.hondappsv.com/files/OM/OM001361NZL/32ZY0637_web.pdf

Edited June 9, 2023 by David Mack