Does this impeller look ok or bad?

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Birdman

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My Mariner 20hp 2 stroke isn't pumping water so I've dismantled it and looked at the obvious. I'm new to boats and outboards but the impeller looks in fairly good nick, but can I have experienced opinions please?

There is water in the pump housing but nothing coming out of the top pee hole when running. I have checked the pipe that comes off the pump housing and that is clear.

Thanks.

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Birdman said:
My Mariner 20hp 2 stroke isn't pumping water so I've dismantled it and looked at the obvious. I'm new to boats and outboards but the impeller looks in fairly good nick, but can I have experienced opinions please?

There is water in the pump housing but nothing coming out of the top pee hole when running. I have checked the pipe that comes off the pump housing and that is clear.

Thanks.

I would suggest replacing it. If this is not your problem it one thing out of the equation.
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It sounds more like the powerhead is blocked with salt. First check the impeller bush has not delaminated and spinning. Try injecting some vinegar up the pee hole the engines that is! Leave overnight and then carefully poke about with some wire.
 
Birdman said:
My Mariner 20hp 2 stroke isn't pumping water so I've dismantled it and looked at the obvious. I'm new to boats and outboards but the impeller looks in fairly good nick, but can I have experienced opinions please?

There is water in the pump housing but nothing coming out of the top pee hole when running. I have checked the pipe that comes off the pump housing and that is clear.
Click to expand...

Reassemble water pump and lower leg. Put in bucket of water and drive it with a drill on the drive shaft. Any output?
 
Thanks all for the quick replies, especially on a Saturday night!

Smithy - I'll check the pipe tomorrow to make sure it's not blocked.

NickC - So reassemble the pump including my old impeller and stick my drill on the splines at the top of the drive shaft? And this should then chuck water out of the smaller pipe, correct?

Cheers all.
 
Birdman said:
NickC - So reassemble the pump including my old impeller and stick my drill on the splines at the top of the drive shaft? And this should then chuck water out of the smaller pipe, correct?
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Exactly.

Next thing to do, but this may depend on exact design of engine, is to remove the hose adapter blanking screw and with the engine put back together and running see if that hole has water output but don't run it for long like this.
 
Thanks Nick.

Not entirely sure what you mean being new but ready to learn and very practical. I Can't get a replacement impeller tomorrow so can test it the way you mentioned first. May just need to come back and clarify when I'm ready.

Thanks again.
 
Most likely a blocked pee hole, completely different to a non-working pump or blocked pipes. Try using a bit of wire to poke out the crud from the pee hole, then run in a tub of fresh water to check. If you are worried about it overheating then only run for a few seconds. I bought a boat with a Yamaha 9.9hp that took 10 minutes to clear the pee hole, I removed the pipe and cleaned it out using a piece of monel wire pushed through, pumped just fine from the pee hole tell tale, the other 95% of the water gets pushed out underneath the water or at the back.
 
Lazy Kipper said:
Most likely a blocked pee hole, completely different to a non-working pump or blocked pipes. Try using a bit of wire to poke out the crud from the pee hole, then run in a tub of fresh water to check. If you are worried about it overheating then only run for a few seconds. I bought a boat with a Yamaha 9.9hp that took 10 minutes to clear the pee hole, I removed the pipe and cleaned it out using a piece of monel wire pushed through, pumped just fine from the pee hole tell tale, the other 95% of the water gets pushed out underneath the water or at the back.
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You've made me think of a vital point I missed. I had the outboard fitted to my boat with the controls as I didn't feel I had enough knowledge. When I got it back I'd bought some muffs to test it and it started fine and didn't think much more. Then I had a thought a few weeks later that I hadn't seen any water coming out so bought a barrel and filled it with fresh water just to make sure the intakes were covered. I started it again to see what happened and no water came out after 10 seconds but it was smoking/steaming so that might well mean the pipe is not blocked?

I stopped the engine straight away.
 
Birdman said:
Thanks Nick.

Not entirely sure what you mean being new but ready to learn and very practical. I Can't get a replacement impeller tomorrow so can test it the way you mentioned first. May just need to come back and clarify when I'm ready.

Thanks again.
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Ok guess I didn't explain too well.

Many engines have a blanking screw or bolt underneath the main body for attachment of an adapter designed for connection of a water hose for flushing purposes. Again not always but often that bolts into the same cavity as the indicator jet. So if you remove that blanking plug, that is if you have one, while the engine is running you should see cooling water being pumped out of that hole.

Thats it for the night, off to the pub now, good luck with it.
 
Ok, makes more sense but not your description Nick, just my lack of knowledge currently.

Thanks again for your help.
 
All the ones I've seen, the arms stick out radially. Yours are swept back so I would think that is old and has been in the pump a long time. Best replace it.
 
Birdman said:
My Mariner 20hp 2 stroke isn't pumping water so I've dismantled it and looked at the obvious. I'm new to boats and outboards but the impeller looks in fairly good nick, but can I have experienced opinions please?

There is water in the pump housing but nothing coming out of the top pee hole when running. I have checked the pipe that comes off the pump housing and that is clear.

Thanks.
Click to expand...

ghostlymoron said:
All the ones I've seen, the arms stick out radially. Yours are swept back so I would think that is old and has been in the pump a long time. Best replace it.
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The impeller looks OK but inspect the ends of the vanes for wear.

The vanes are straight when new but a used one will always be curved... the older it is the more curved it will be

The impeller drive key is in position ??? easy to lose it when reassembling


Check the Pee hole, hose and connection at the engine end for blockage as suggested but steaming is a sign that there is inadequate water flow through the engine.

Check for overheating. It should be possible to touch and maintain finger contact briefly on any part of the engine except for perhaps the head close to the spark plugs. If you cannot or if a splash of water sizzles and bois off its overheating.

Difficult to give precise info without exact model details ( serial number or age)

Do you have an owners manual if not down load one from Brunswick marines down load center http://download.brunswick-marine.com/download/main;jsessionid=105vjo07c1lcd?type=corp
 
I had same thing last year albeit on smaller 8 hp two stroke ,eventually I removed cyclinder head which being two stroke is simple enough and found the water passageways stuffed with a mixture of hardened salt and sand , it took a while to clear everything completely but not such a bad job , my first thought like you was the impeller but as it looked okay I thought even a worn impeller would produce some flow . By dismantle lying very carefully I was able to re use the gaskets so the job only cost me time .Good luck .
 
ostra4 said:
I had same thing last year albeit on smaller 8 hp two stroke ,eventually I removed cyclinder head which being two stroke is simple enough and found the water passageways stuffed with a mixture of hardened salt and sand , it took a while to clear everything completely but not such a bad job , my first thought like you was the impeller but as it looked okay I thought even a worn impeller would produce some flow . By dismantle lying very carefully I was able to re use the gaskets so the job only cost me time .Good luck .
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Get hold of some citric acid ( a benign acid used in jams, soft drinks etc) and work a solution back into cylinder head which is likely blocked; leave it to soak and then deposits will be dissolved. (Quite a lot of citric acid in coke etc so that might work too!)
Lie outboard horizontally and put solution into pump intake and/or through the tell tale hole. You do not need to dismantle cylinder head but if you did hunwould of course see the blockage, invariably caused by not frequently flushing with fresh water.
Good luck.
 
SimonJ said:
Get hold of some citric acid ( a benign acid used in jams, soft drinks etc)
Click to expand...

Benign is probably the operative word. I doubt if even something quite aggressive like hydrochloric would do much good. As already suggested take the head off and physically clean the water passages.

Then, if you are determined to avoid a recurrence, flush EVERY time you use the engine. No excuses :D
 
Well new impeller fitted and all back together today. I get a slight drip from the pee how but nothing of any substance. What I did notice though is water coming from low down at the front of the outboard, from the top of the gear housing.

When I had it apart, the old water pump housing didn't look in great shape but I wasn't sure how good it had to be considering there's an O ring in there. So I'm going to replace the water pump housing and all the washers in case it's leaking from there, that's all I can think of. That would also reduce the pressure on the water going up the pipe, hence I would guess it's finding the easiest route out.

Looking at the serial number, it just tells me it's a 1985 Belgium produced 20 (2 stroke). One site I've found kit on shows a very similar kit but they class it as a 20XD. What's an XD model? Serial number is 9525762
 
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