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Discussion Starter · #1 ·
So I’ve got a 15hp Mercury it runs fine tool the leg of tested it in a bucket with a drill and got a good spray of water from the water pump also checked impeller while it was off. Put some air through the copper intake pipe and there’s air coming through. Put it all back together tried it in a bin of water and got no water through the pee hole. Added more water up to where the exhaust holes are and got a nice steady stream through the pee hole. Can anyone tell me what’s going on I made doubly sure the copper inlet pipe went back in the water pump correctly. If anyone can help would be greatly appreciated.
 

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You seem to need a good depth of water in a container to get flow from the pee hole, not sure why. Perhaps the water gets disturbed and shallow round the intake when running?
That’s exactly right, if it’s properly assembled and all working some engines need more water in the bucket because the exhaust and or prop disturb the limited volume of water in the bucket. Use flush muffs and the problem should disappear.
 

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Discussion Starter · #5 ·
Thanks for all your help guys I understand it needs to be fairly deep as in covering the whole lower leg section but the only way I could get it to pump water out the pee hole was to fill up the bin meaning the water was just fellow the mounting bracket way higher that it would be in reality. With the leg off it works fine in a bucket but it’s just not sending water to the pee hole and I can’t fathom why. Only thing I can think is a poor connection to the long copper intake pipe the runs to the head?
 

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Yes you may to not to connected the pipe properly. An old ob i did to have was a fiddle to do when i did to take the leg off.
It also may to a small block into the head. If you do thick mono you can to fish it through to clear.
To check pipe first.
 

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Discussion Starter · #8 ·
Yes it is a nightmare to get it connected properly as there no visibility. We have taken the inspection cover off the head and checked all the water ways are clear it’s so frustrating because the engine runs lovely. Would it be worth replacing the impeller and water pump even though with the leg off it pumps water? Maybe it’s not producing enough pressure to get up the pipe?
 

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Yes it is a nightmare to get it connected properly as there no visibility. We have taken the inspection cover off the head and checked all the water ways are clear it’s so frustrating because the engine runs lovely. Would it be worth replacing the impeller and water pump even though with the leg off it pumps water? Maybe it’s not producing enough pressure to get up the pipe?
What did you the leg off for?
Always worth to change impeller. It may to look okay but could be 10 mins from break apart. If it not to be done this year, yes to change.
Buy you some xray vision for the pipe.
 

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Discussion Starter · #12 ·
The outboard is new to me yes checked the woodruff key that connects impeller to drive shaft it seems fine took everything off bellow the power head checked all the pipes everything seems fine took inspection cover off the power head water ways are not blocked the only thing we are unsure of it weather it’s seating properly when we push the leg back on I’ve ordered a water pump kit so will change that and try again. If it’s not that I don’t really know what else it could be?
 

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If you did toncheck all else, and it to not be the pipe i to not to know further.
It to be a long time since i did work on an outboard. I to think the pipe may to push into the top and to the bottom on some models and makes. If you do to try to take the pipe from the head you can to seat it onto the pump and to try that way.
Or to maybe tape the pipe so it to extend and to have a guide to go into the slot. it not to go anywhere like into the engine so to be easier that way maybe.

If this not to work then to take to a mechanic who can to diagnose and to fix But do please poat the solution back so people to know what it was.
 

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It’s possibly the water tube is broken/corroded through. With the lower unit removed, use a short piece of fuel tube one end into into a hosepipe, the other attached to the water tube and fix it up so you can flow some water up the leg, takes a good look up there while it’s flowing to see if water is leaking out the tube, this should also give you a flow out the tell tale and back down with the exhaust, if that all works then it’s likely the water pump is not efficient enough, take a good look at the impeller and sleeve where the water pipe meets into the pump outlet.
 
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