Motor not peeing water

Nov 19, 2011
1,489
MacGregor 26S Hampton, VA
I have a 9.9 merc 2 stroke. It's been a great motor. This week while out putting around I noticed I had no stream of water coming out. Is this typically just an impeller change? I always lift my motor out of the water when I am in my slip. So it's not likely marine growth. I don't want to run the motor when I don't see water coming out.

On this motor, there are no side inlets. There is just one and it's just above the prop. Not sure how one would flush it short of taking it off the boat and filling a barrel with fresh water.

What say you?
 

Joe

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Jun 1, 2004
8,198
Catalina 27 Mission Bay, San Diego
Get an owner's manual and learn how to service your motor. Besides changing the impeller (which means you will have to detach the lower unit) you should inspect the thermostat.
 
Aug 29, 2015
5
Ranger 29 Victoria
If you're running in salt water sometimes the "pee" tube at the outlet can become plugged with salt debris. I've had to ream mine out on a couple of occasions. First time a fine wire did the job. The second time I had to remove the tube to clean it out. I would do this before I started pulling the bottom end off for an impellor change but if your motor is getting on in hours you should think of changing the impellor anyway. Are there other signs the motor might be running hotter than usual like too hot to touch the block. If the block is obviously hotter than usual then it probably is the impellor.
 

Johnb

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Jan 22, 2008
1,461
Hunter 37-cutter Richmond CA
In the California delta there were bugs that used to lay eggs in the rubber tube on the cooling water outlet and then plug it with mud. On the Honda you could just pull it off and roll it between your fingers to get the plug out followed by some strange little green crawling things.
 

Joe

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Jun 1, 2004
8,198
Catalina 27 Mission Bay, San Diego
Here's part 1 of service manual for Mercury 9.9 two stroke O.B.

This is part 2 of the service manual.

In Part 2, looking at section 4, "cylinder block and covers" you can see that the tell-tale hose[part #30] (pee hole) and the thermostat[part 37] housing are at the rear and on top of the power head. It's right above the spark plugs... so you can easily service this area with the motor tilted up and the cover removed.

Anyway... sometimes when the thermostat malfunctions... water is not routed through the tell tale hose....

Only 6 - 8 HP pre 2000 models were not equipped with thermostats.

The point is... if you haven't serviced your OB for a while... these parts will deteriorate and need replacing... just like an automobile.
 
Nov 19, 2011
1,489
MacGregor 26S Hampton, VA
Thanks to all. I will pull the cowl cover and see if I can see this tube.
 
Feb 17, 2006
5,274
Lancer 27PS MCB Camp Pendleton KF6BL
Before I run my outboard, I will always attach the flushing hose and run it for a few minutes. This will allow me to check to see if there is any obstruction before starting the engine.

I also had problems with bugs getting into the pee hole. So I inserted a tooth pick to basically block the hole from bug infestation.
 

JTulls

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Dec 6, 2014
89
International 14 and J-Boat J80 San Diego
Try just flushing it with a hose and seeing if you can push a stream out -- if anything you'll be able to clean out the hose if it's gunked with salt or grime. Other than that my guess would be the thermostat.
 
Nov 19, 2011
1,489
MacGregor 26S Hampton, VA
Like I said this one doesn't have the side intakes like my old 25hp merc had. It has one opening above the prop and ear muffs won't work . I'll swim a running hose around and try to force it in.
 
Aug 29, 2015
5
Ranger 29 Victoria
Start with the simplest possible solution first and make sure the "pee hole" outlet by the powerhead is not plugged. The "pee hole" is the smallest opening in the cooling system so it's usually the first to plug up.
 
Feb 17, 2006
5,274
Lancer 27PS MCB Camp Pendleton KF6BL
Like I said this one doesn't have the side intakes like my old 25hp merc had. It has one opening above the prop and ear muffs won't work . I'll swim a running hose around and try to force it in.
My first Yammy had no flushing attachment. So I went to Home Depot and got an adapter to attach to the pee hose to back flush. You will have to use low water pressure so as not to bust any seals. As long as you have water coming out of the lower unit then the path should be clear.
 
Jan 27, 2008
3,086
ODay 35 Beaufort, NC
I had a 9.9 mercy two stroke and it had a fitting you could attach to connect a hose to flush it out after running in salt water. It was near the bottom of the power head. I had to buy the fitting to screw in the hole. See if yours is similar. Maybe get an owners manual it should describe it.
 
Jun 2, 2004
3,554
Hunter 23.5 Fort Walton Yacht Club, Florida
Flush Adapter

There is one available. It looks like half of the muffs you are familiar with.the problem is the hose sticks straight out the bottom and the prop has to be removed to use it. I pulled the hose attachment out of mine inserted a plastic elbow attached a piece of tubing to one end and stuck the other end back in the cup then put a hose end on the other end of the tube and it slips right on.
 
Jun 4, 2004
287
Beneteau Oceanis 352 NYC
I used Salt-Away and water in a 5 gallon bucket with the lower unit in the bucket, my peeing came back to normal after a few minutes of running the engine
 
Aug 29, 2015
5
Ranger 29 Victoria
I used Salt-Away and water in a 5 gallon bucket with the lower unit in the bucket, my peeing came back to normal after a few minutes of running the engine
Hey! Now I like that idea. Thanks for the tip. Think of it as Ex-lax for the motor.