Impeller blow out

So wasn’t gonna post about it bc it was pretty bonehead move on my part but maybe it’s useful.

Last fall changed the water pump on my 120. Everything went well, continued on to take apart the carbs and whatnot so turned off the water, well decided to try the new tweaks and after smelling some weird burning smell noticed the water never got turned back on. Yikes.

Motor didn’t run for longer than a minute max, 30seconds more abouts but either way, in that short time the warpage already took place.

Plenty of fellows at the launches during cold water who really flush their systems out for extended periods, beware! Maybe this helps others, maybe not, make sure to turn on those hoses fellas!

Attachments:

1. 

   IMG_20170408_152919693.jpg
   

sorry to hear you are learning the hard way Nick!
wont forget that one will you???
check its plastic housing to make sure you didnt warp it.

it makes me cringe when I see someone start their motor up with it out of the water at the boat ramps just before they launch.
for the life of me I dont understand doing that,it takes as you learned,less than fifteen seconds for it to burn out the impeller,quicker if they rev the snot out of it.
water is the only lubrication/coolant that pump gets and with the tension its under,it generates heat right now.

there is no need to run it after pulling it out of cold water either,the water runs right back out the same hole it came in for the pump.

I’ve seen guys pull out in the late fall and run the motor for a few seconds to get all the water out of the lower unit before it freezes. I can see why they’d do that…but I always cringe at the thought of the impeller running around dry.

SR

Steve Root wrote:

I’ve seen guys pull out in the late fall and run the motor for a few seconds to get all the water out of the lower unit before it freezes. I can see why they’d do that…but I always cringe at the thought of the impeller running around dry.

SR

That would make no sense since running the motor would not squeeze any water out of the theoretically “sealed” lower unit. Only way is to open the plug and check for any water, better yet just replace lower unit lube.
FWIW, the only time I have ever run the motor (well not run the motor) would be just to start it for a second to make sure it fired up before releasing from the trailer.

Walleyestudent Andy Cox wrote:

That would make no sense since running the motor would not squeeze any water out of the theoretically “sealed” lower unit.

This blows all the water out of the water pump. Since the impeller is still wet, there is no friction. We are talking a 2-3 second burst here in cold weather.

-J.

Do you think getting a block in your nozzle where the water comes out would cause damage?
I had it happen twice last year where I sucked in a small piece of a stick and turned around to see no water coming out. I assume the pump isn’t pulling in any water when you have a block, but I would hope it got some water on it before the blockage occurred.

Yah that ones smoked! Good post though thankyou. Is powerhead ok?

Ive plugged my pee pee system several times by hitting stuff, usually wood while at speed. Just because the motor isnt peeing does not meean that the water pump is not doing its job. Thats why a water pressure guage is so important.

I think the old thought that by the time the audible alsrm sounds you already have cylinder damage holds sand.

red89 wrote:

Do you think getting a block in your nozzle where the water comes out would cause damage?
I had it happen twice last year where I sucked in a small piece of a stick and turned around to see no water coming out. I assume the pump isn’t pulling in any water when you have a block, but I would hope it got some water on it before the blockage occurred.

The pee hole is just a telltail signal to tell you the water pump is working. The majority of the water runs through the engine block and out the exhaust port in the hub of the prop. Still a good idea to stop and clear the clog in that little tube, but chances you caused any damage from that is nil.

Steve Root wrote:

I’ve seen guys pull out in the late fall and run the motor for a few seconds to get all the water out of the lower unit before it freezes. I can see why they’d do that…but I always cringe at the thought of the impeller running around dry.

SR

Still not a good idea considering the motors drain out with gravity and there should be little if any water left in the motor if it is vertical and drained for a minute or two. The water doesn’t freeze that fast. A few drops of water in various areas isn’t going to hurt anything.

munchy wrote:

Still not a good idea considering the motors drain out with gravity and there should be little if any water left in the motor if it is vertical and drained for a minute or two. The water doesn’t freeze that fast. A few drops of water in various areas isn’t going to hurt anything.

That is exactly what I thought. Always lower the motor all the way down when you tuck it away for the winter!

Walleyestudent Andy Cox wrote:

That is exactly what I thought. Always lower the motor all the way down when you tuck it away for the winter!

I should have mentioned this is for guys who run their boat all winter. Guys who are pulling out in sub freezing temps then parking an an unheated garage like me.

No need for most boaters to do this.

-J.