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Strange cooling problem with BF40A

B

Blue Skies

New member
I recently purchased a boat that came with a nice dinghy with a 2007 40 HP four stroke Honda outboard. During the purchase process, the broker and I took the dinghy out and it performed well. I believe the tell tale was pissing out the side of the engine. WE finished up and the broker said he would lift the dink back up after I had gone. I suspect that he may not have flushed the engine. The boat sat from the end of December until last week while we went thru the purchase and repair process.

I took the dinghy down last week and it started right up, but no water from the tell tale. I assumed that the impeller was probably shot so I loaded it on a trailer and brought it home. I rebuilt the entire water pump with an OEM kit and reinstalled the lower end on the motor. I was super disappointed to see that I still had no flow at the tell tale. I pulled the discharge hose and the fitting going into the block, everything seems clear, but I'm getting no water at all. I even tried running a weed wacker cord down thru the fitting but encountered no obstructions. I then removed the water jacket cover. It appeared to be clear, but it looks like someone had added some gasket maker to the o-ring/gasket. I then turned the water on to the ear muffs again and started the engine. I believe that I should be seeing water flow in this jacket cover, but once again I had no water at all.

At this point, I'm stumped. I'm thinking of pulling the lower end again, putting it into a tray of water and spinning the shaft with a battery drill to prove that the pump is working. I don't have a manual yet so I don't know where else to look. Any of you Honda experts have any sage advice for me?

Thanks , in advance.

Blue Skies,
Dave
 
Hi,

You might want to pull the intake screens off and make sure nothing like seagrass or seaweed or "other" is fouling the pump intake.

If that looks ok, I would try unscrewing the fitting that the tell tale tube attaches to from the engine block.

Put the lower end in a trashcan full of water... stand clear... and start the engine.

But be ready to shut it down immediately!

If the pump is good and the water tube is hooked up properly then anything in the bypass circuit WILL be instantly dislodged and ejected along with LOTS of water.

Trimmer string, wire and compressed air only works sometimes. This works every time for clearing the passage.....if all else is good that is.

If still no water then, yes, pull the lower end and investigate because that's where you'll find the problem.


Good luck (but you're probably going to get wet! ;>)
 
I had this exact chronic problem with my 2001 BF40 LTRA beginning 5 years ago. Replaced the water pump many times and flushed with product to remove corrosion, but the output stopped every time I was out in the boat, extremely frustrating for several years.

Turned out to be corrosion blockage: white scale particles accumulating in the bottom of the interior engine block water passages and blocking the tell-tale outlet.

Solution: with the motor running, remove the water exit hose from the tell-tale port and use a straight section of clothes hanger wire to insert into tell-tale and remove, jam in and pull out, repeat repeat until the particles clear and output is strong. If this is your problem too, the particles will accumulate in water under the tell-tale outlet at the base of the engine block.

Always keep a straight 10-inch section of clothes hanger wire in the boat to treat blockages this way as they form while the motor is running. For me, the particles eventually cleared and now the stream is strong.
 
alanization said:
I had this exact chronic problem with my 2001 BF40 LTRA beginning 5 years ago. Replaced the water pump many times and flushed with product to remove corrosion, but the output stopped every time I was out in the boat, extremely frustrating for several years.

Turned out to be corrosion blockage: white scale particles accumulating in the bottom of the interior engine block water passages and blocking the tell-tale outlet.

Solution: with the motor running, remove the water exit hose from the tell-tale port and use a straight section of clothes hanger wire to insert into tell-tale and remove, jam in and pull out, repeat repeat until the particles clear and output is strong. If this is your problem too, the particles will accumulate in water under the tell-tale outlet at the base of the engine block.

Always keep a straight 10-inch section of clothes hanger wire in the boat to treat blockages this way as they form while the motor is running. For me, the particles eventually cleared and now the stream is strong.
Click to expand...
Thank you, I’m going to try this.
 
Thanks for your ideas... A questiion on my honda outboarrd...

Iv noticed the short rubber tube that goes over the water tube can be pushed up so it gives no seal between the output of the water pump and water tube. The tube seal has no stop to prevent it slipping up the tube. If not careful when installing the lower into the upper case you can easily push that tube seal up on the alum tube. i think the water pump output design is a weak point, if not sealed just right it allow water to be pumped in the lower cavity instead up the water tube for cooling..
Im having trouble get the lower installed without screwing up this connection.
any ideas are appreciated!
brad p
 
Hi,
I haven't done a pump on one of these but I do understand what you're saying.


My experience with the water tube seal rings (item 9 in link above) on pumps I have worked on is that they fit snug enough on the tube they don't tend to move out of place as easily as you say.

So, I'm wondering if the ring you have is old or distorted/deformed in some way?

Like all rubberized parts they will tend to harden over time and that could cause problems.
You may want to try using a new one to see if that helps with the issue.

Good luck.
 
JGMO, great points.... the tube seal is new. it is somewhat tight on the alum water tube, but messing with the lower to get it to mate with the splines its easy to accidentally push the seal tube up and away from the end of the water tube.... I wish they designed this with a pump exit tube that fits inside the water tube, maybe with a grommet to help the seal. IMHO this is a very bad design that is all that and a bag of chips when new, but as things age, not so good.
Im going to put a pipe clamp on the rubber seal tube to increase the tension and hold in place. I wish you could see it when mated, but a guess will have to do. PITA in my opinion..

thank you for your ideas
brad
 
Well, like I said, I have not worked on a 40 so I don't know.

I was thinking that maybe wrap a sturdy rubber band on the tube might work or even a zip tie to form a "flange" or step on the tube to prevent or, at least, resist slippage.

But you're the man on the scene so let us know how your solution works.

Good luck.
 
I realize this is a year old thread. I've just bought a boat with a bf40a outboard.
In replacing the water pump I think that grommet is supposed to be installed in the water pump cap, then when you install the lower unit the pipe slides into the grommet. By saying "in the water pump cap" I mean the grommet goes in the underside of the cap not on top. Please let me know if I'm wrong because that's the way I understand it.
 
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