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Peeing Problem

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Don Coyote

New member
Well,....... not to get TOO personal,..... yes I'm speaking about my boat motor.

......... (THIS time).

I just "maintained" the impeller in a friend-of-mine's 1965-ish Mercury 6hp. (Some OTHER guy screwed it up).

I got the engine to "pee", but it only does it at idle. When I give it gas, it stops peeing. I idle down and it starts again... and the water gets pretty hot, then cools down.

I work on air-cooled snowmobiles, I don't work on water-cooled engines. (But hey....... if it burns gas, I'll wrench on it when it needs it).

I assume this is NOT normal? Shouldn't it pee even harder when I give it gas?
 
Are you running it in a barrel? Is it running in gear? I've seen guys report this problem and it turns out they're running in a barrel and in gear. The prop stirs the water up so much that the pick up for the water pump is no longer submerged. Get that motor in the water somewhere and see what it does. Or if you're suspecting a water pump impeller issue, drop the lower unit and replace the impeller. Not a tough job for a snow mobile mechanic!! Lots of videos out there if you need help.
 
It's in a barrel, but I've been running it in neutral.

The last Guy that worked on this thing "claims" that he replaced the impeller. When I got to it, I'm pretty sure it wasn't new. The "blades" were already bent over, and he might have put the old impeller back in backward... because half the blades were facing the wrong direction. (I can probably post a pic when I get home from work). After I got done with it, all the blades were facing the right way and everything looked pretty good. And like I said..... it pees now, just not like I think it should.

I have a 7.5hp just like this one, just a little newer. I've only ever used it once. (long story). My Kid used my old jon-boat and the 7.5 last year and he said it wasn't peeing, so I changed the water pump......... and then it hasn't been used since, I haven't even put it in a barrel to test it. (I'll probably do that when I'm done with this 6hp).
 
Having had extensive playing experience with my dad's 10 HP Scott-Atwater engine in a 55 gallon barrel, if combustion gasses enter the water it will heat up regardless of the shifter position. Course if you put it in gear and increase the RPMs the warming water will exit the barrel and you will have to have the garden hose replacing it which will cool things down. If you don't replace the water once you stop agitating the water in the barrel it most likely will be too low for the water pump to pump properly......contrary to you published problem.......which really doesn't make sense.

The water pump is not a "lifting" pump like one would have sitting on a dock sucking water out of a pond or what have you. When on a boat and at rest the impeller is several inches below the water's surface and it is well submerged. When underway, once the back wash leaves the transom (boat getting on plane), water inlets on the lower unit are positioned to accept "ram water" to "feed" the water pump.

Water pressure varies as a function of RPMs as folks with water pressure gauges in their boats realize. My experience with the pee source is that it's connected to the exhaust water jacket cover because the exhaust cooling water applied to the crankcase combustion exhaust plate is not connected to block internal passages which are usually controlled by a thermostat and larger engines with a high RPM bypass "popoff" valve allowing for more flow to dissipate the increased heat.

I don't know if anything in here will help you but I offered it in good faith.
 
Texasmark said:
When underway, once the back wash leaves the transom (boat getting on plane), water inlets on the lower unit are positioned to accept "ram water" to "feed" the water pump.
Click to expand...
Thanks, Tm......... The water in the barrel is higher than the pump. I know that these engines don't use a "self-priming" pump.

I suppose I/we should try giving it some "ram water" and see it that is all that I am missing. Get ot out of the barrel and into the lake. (More fun that way, anyway). :cool:
 
Don Coyote said:
Thanks, Tm......... The water in the barrel is higher than the pump. I know that these engines don't use a "self-priming" pump.

I suppose I/we should try giving it some "ram water" and see it that is all that I am missing. Get ot out of the barrel and into the lake. (More fun that way, anyway). :cool:
Click to expand...
Sounds like a plan and you may be pleasantly surprised.
 
Fact----There is a plastic washer ( unless updated ) at the top of the water tube.-----This washer melts on severe overheat.----Blocks waterflow after impeller replacement.-----The new replacement is a more durable material!
 
Here is a pic of the animal after I got the cover off. The guy told my Buddy that he put a new impeller in it.

I'm certain that he lied. It looks like he took it all apart and then put the impeller back in upside-down,... as it was already worn-in and rounded in one direction. (A NEW impeller has straight fins, not curved). Before I took the cover off, I put the lower-unit in a bucket of water and spun the shaft with an electric drill....... and the pump was NOT pumping. That's when I disassembled the pump and took the pic of what I found.

After I reassembled it, I did the "drill thing" again and it WAS pumping pretty good.

I'm thinkin' I'm done for the moment...... time to get it on a boat and see how it does in the real world. (I'll just give it back to Roy and let HIM test it out). I don't intend to charge him for this,..... but he'll probably insist on throwing me a bone.

Whatever,..... friends do what friends do.

......... HEY,..... my pic won't post......... do I need a minimum number of posts before I can post a pic?

(Lol,....... I just read that back..... sounds like there should be a "peck of peppers" in there, somewhere).
 
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