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BF20D water pump problem

T

Tedmarx38

New member
I have a new impeller arriving on Thursday but will value guidance on how to proceed in light of this sequence.

The old one was two years old but I’d only run the boat for five hours over the past two seasons, on four outings. The other day, I started the engine for the first time this spring with the muffs and hose attached, as I’ve done many times. It took a few stalls and then maybe 30 seconds of operating before I got a pee stream. I thought about shutting it off before then but with the auto shutoff backing me up, and figuring I might need a new impeller anyway, I let it play out.

I revved the engine and there was a strong stream. It felt warmer than usual though and after one minute or so the stream felt hot, the overheat buzzer sounded, and the thing shut off.

I retrieved the impeller and while some of the vanes were chipped, it didn’t look all that bad. I’m concerned that something else is amiss and don’t want to put the new impeller on and have it get ruined.

What all should I check regarding whether there’s a bigger problem and how? I don’t want to tear the motor to pieces because I’m not proficient at this stuff. Nothing visually obvious (mouse or bees nest etc). Thanks.
 
Well, not trying to be rude to you but I would caution you about ever using thr engine protection system as a "back up". Intentionally overheating your engine risks causing major damage.

The fact that it took so long to get a pee stream suggests that the water tube may have had a blockage.

On the other hand the tell tale bypass could have simply been blocked and then cleared itself. Take particular note as to the routing of the tell tale tube as you remove the port side cover. Unscrew the tell tale tube nipple from the engine block and push garden hose water or compressed air through the tell tale hole in the block. This will clear most any debris from the bypass and out of the water tube.
If the tell tale tube isn't soft and supple, replace it as a hardened tube will trap debris. Take particular care to route it back out to the side cover fitting just as it was before.

There could be a problem with the water tube grommet. Item 3 in the link below.

https://www.boats.net/catalog/honda...00001-to-bamj-1499999/oil-case-oil-pan-gasket

Try to account for any pieces of the impeller. They will usually fall and end up behind the water inlet screens but can sometimes be thrust up into the water tube and even the engine block.

It is also very likely that the engine thermostat may be stuck closed. You should remove it and inspect and test it at the very least but I recommend replacing it if you've never done so.

I always recommend replacing the entire water pump assembly instead of just the impeller. Always use a new drive key too. If you look closely and carefully enough, you will see all those items have some degree of wear.

Good luck.
 
jgmo said:
Well, not trying to be rude to you but I would caution you about ever using thr engine protection system as a "back up". Intentionally overheating your engine risks causing major damage.

The fact that it took so long to get a pee stream suggests that the water tube may have had a blockage.

On the other hand the tell tale bypass could have simply been blocked and then cleared itself. Take particular note as to the routing of the tell tale tube as you remove the port side cover. Unscrew the tell tale tube nipple from the engine block and push garden hose water or compressed air through the tell tale hole in the block. This will clear most any debris from the bypass and out of the water tube.
If the tell tale tube isn't soft and supple, replace it as a hardened tube will trap debris. Take particular care to route it back out to the side cover fitting just as it was before.

There could be a problem with the water tube grommet. Item 3 in the link below.

https://www.boats.net/catalog/honda...00001-to-bamj-1499999/oil-case-oil-pan-gasket

Try to account for any pieces of the impeller. They will usually fall and end up behind the water inlet screens but can sometimes be thrust up into the water tube and even the engine block.

It is also very likely that the engine thermostat may be stuck closed. You should remove it and inspect and test it at the very least but I recommend replacing it if you've never done so.

I always recommend replacing the entire water pump assembly instead of just the impeller. Always use a new drive key too. If you look closely and carefully enough, you will see all those items have some degree of wear.

Good luck.
Click to expand...

Thanks. I will replace the entire assembly and let you know what happens. At this point, if it fails I’m going to dump the pontoon along with the engine etc. I’ve wasted way too much time on this thing and don’t use it much. Cheers.
 
Sorry, I meant to say starboard side cover when replacing/removing the water tell tale tube.

Good luck.
 
jgmo said:
Sorry, I meant to say starboard side cover when replacing/removing the water tell tale tube.

Good luck.
Click to expand...

So I’m one er trip and four stitches into this one already. Tried blasting water from the pressure washer up the water tube to see if it would come out the tell tale. It didn’t. And I got cut trying. So…. If the the thermostat is stuck closed would that cause this, or am I going to have to dissemble a bunch of stuff to see if there’s a blockage? The way the tube sits up in the housing makes it tough to tell if I’m even hitting into it when I test it. It would seem that there should be little resistance and with the motor tilted up up you’d think some sort of stream would appear.

Its perplexing though because when it failed initially, the stream was strong once it started. That said, I don’t want to burn another impeller up. I haven’t checked the term pay yet but I believe If its stuck closed, the telltale should still show a stream?
 
Well, I guess you misinterpreted my first reply. Third paragraph...I suggested to you to remove the tell tale tube/hose along with the stbd cowling cover. Then remove the tell tale tube/hose fitting from the engine block and force full hose water pressure.... and/or compressed air.... into that passage to see if you can clear it that way.

BUT....stressing out about the tell tale not peeing won't solve an overheat. The tell tale is just an indicator and the engine will NOT overheat if it is COMPLETELY blocked. A stuck T-stat will NOT block the tell tale. The tell tale passage is a bypass or T circuit. Water should still circulate to the engine if it is completely clogged up. That is IF the water pump is actually pumping.

Remove the fitting, backflush that passage and, if you can, reinstall your old impeller, leave the fitting out and side cover off. Run the engine briefly IN A BUCKET OR TRASHCAN with enough water to cover the splash plate. Even with a damaged impeller, water should GUSH out of the tell tale hole.

Troubleshooting a waterpump problem by using the muffs just doesn't give you the information you need. Use the trashcan and run your tests in short bursts to avoid overheat. If you don't get a gusher from the tell tale hole, can choose to try back flushing again.

Regardless of the outcome of that, I urge you remove the t-stat and see what is going on there. With it removed, you can again start the engine and water should gush out. If it doesn't then the pump isn't pushing water and you will need to find out why.

Make sure there's nothing blocking it's ability to pull in water. Make sure the drive key didn't fall out.

I have seen pumps with only 1 impeller vane left move enough water to have a tell tale stream and the engine not overheating right away so it should be something you can easily see or there's a blockage someplace.

While the stat is out and the gearcase off you can use the hose to backflush the system. Put the hose in the openings you see in the housing and use a rag to form a seal to help direct and maximize the water pressure.

When you have verified the t-stat will open in a pot of hot water (about 150° to 160°.f) and you have no blockages, you can fit a new pump.

Good luck
 
jgmo said:
Well, I guess you misinterpreted my first reply. Third paragraph...I suggested to you to remove the tell tale tube/hose along with the stbd cowling cover. Then remove the tell tale tube/hose fitting from the engine block and force full hose water pressure.... and/or compressed air.... into that passage to see if you can clear it that way.

BUT....stressing out about the tell tale not peeing won't solve an overheat. The tell tale is just an indicator and the engine will NOT overheat if it is COMPLETELY blocked. A stuck T-stat will NOT block the tell tale. The tell tale passage is a bypass or T circuit. Water should still circulate to the engine if it is completely clogged up. That is IF the water pump is actually pumping.

Remove the fitting, backflush that passage and, if you can, reinstall your old impeller, leave the fitting out and side cover off. Run the engine briefly IN A BUCKET OR TRASHCAN with enough water to cover the splash plate. Even with a damaged impeller, water should GUSH out of the tell tale hole.

Troubleshooting a waterpump problem by using the muffs just doesn't give you the information you need. Use the trashcan and run your tests in short bursts to avoid overheat. If you don't get a gusher from the tell tale hole, can choose to try back flushing again.

Regardless of the outcome of that, I urge you remove the t-stat and see what is going on there. With it removed, you can again start the engine and water should gush out. If it doesn't then the pump isn't pushing water and you will need to find out why.

Make sure there's nothing blocking it's ability to pull in water. Make sure the drive key didn't fall out.

I have seen pumps with only 1 impeller vane left move enough water to have a tell tale stream and the engine not overheating right away so it should be something you can easily see or there's a blockage someplace.

While the stat is out and the gearcase off you can use the hose to backflush the system. Put the hose in the openings you see in the housing and use a rag to form a seal to help direct and maximize the water pressure.

When you have verified the t-stat will open in a pot of hot water (about 150° to 160°.f) and you have no blockages, you can fit a new pump.

Good luck
Click to expand...

I’m ditching the thing for whatever I can get. We rarely use it, the lake we frequent is overly crowded, and the craft takes up more time than it’s worth. Cheers.
 
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