Intermitent water spray

[ecaroppo]

Hello:

I have a 1975 15 hp. Johnson. I just dropped the lower end to inspect the water pump because I wasn't getting very much water spray out of the top outlet. Everything looked to be in order. Once I re-assembled everything and sparked her up, water imediatley started to shoot out the orifice, More than ever before. I thought this was great so I shut it down. After about 5 min. I decided to run the fuel out. So i started it again and ran it until it bogged out. Problem is that this time there was NO water coming out for the duration of the motor running. I read that a thermostat would have to open up. Does this motor have one? If so why do you think I got spray before and not after? I am running the motor in a garbage can. Is this normal?

Thanks

 

[Joe Reeves]

Re: Intermitent water spray

Water should shoot out that hole with quite a force all the time regardless of the thermostats function. Water flows out the smaller holes/slots just above the cavitation plate when it opens.

I suspect that the water level in the garbage can had dropped somewhat and that might have allowed air to gain access to the water pickup areas. Always have the water level 2 or 3 inches above the area where the lower unit bolts on.

 

[ecaroppo]

Re: Intermitent water spray

Thanks for the quick reply. I did fill up the garbage can above the bolts before restarting it. Could there have been too much air in the water from the previous run?

 

[Joe Reeves]

Re: Intermitent water spray

No, that can't happen. Try another run and if you still have a problem, drop the lower unit to inspect your work. Perhaps the water pump plate to lower unit and impeller housing to plate wasn't sealed properly.

Use Boat Armor Sealer 1000 as a sealer, available at automotive stores and possible Wal*Mart, K-Mart etc.

 

[ecaroppo]

Re: Intermitent water spray

Hello:

I ran the motor today and still no water! I dropped the lower unit and shot water up the feed tube to notice that the water was coming back down the outside of the feed tube. So I pulled the power head and ordered a new water pump kit, gasket and grommet for the feed tube. Now I've noticed that there is only an in for the water and no out. So can anyone shed some light as to how this system works? Again the motor is a 74 johnson 15 hp. I am confused!!!!!!!

 

[Joe Reeves]

Re: Intermitent water spray

Water exits from the powerhead down the exhaust housing and then out thru the propeller opening. It also exits out the two holes at the top rear portion of the exhaust housing (lg hsg between PH and LU).

 

[iwombat]

Re: Intermitent water spray

While you have the powerhead out you might consider retrofitting a tell-tale. I think it'd save you some grief in the long-run.

 

[iwombat]

Re: Intermitent water spray

Hello:
So I pulled the power head and ordered a new water pump kit, gasket and grommet for the feed tube.

Okay, I read that again. Do you mean you pulled the lower-unit? You really didn't need to pull the powerhead to get at the water pump.

 

[ecaroppo]

Re: Intermitent water spray

How would I go about with the retro fit?

That aside! So once I get this thing back together and do the same with shooting water up the feed tube. It should exit through the exhaust housing and not down the outside of the tube?

 

[Joe Reeves]

Re: Intermitent water spray

Water will stop at the thermostat due to the fact that it is not open when cold. If you're going to experiment, temporarily remove the thermostat BUT DO NOT run that engine without a thermostat.

 

[iwombat]

Re: Intermitent water spray

The retro-fit is as simple as drilling and taping a hole in your crankcase someplace - I'm sure someone here knows the best place. And putting in some pipe-fittings and a tube. It's a pretty simple procedure.

I'm genuinely confused at what you're doing here though. It's just that it's not entirely clear from your post. I get the water pump replacement part. So, the LU is off. Are you replacing an exhaust gasket, and resealing where the water intake goes into the powerhead?

 

[ecaroppo]

Re: Intermitent water spray

Yes! That is exactly what I am doing. I figure that there must be something wrong with a seal at the top of the supply tube.

 

[iwombat]

Re: Intermitent water spray

The part#s for later model water indicators are:
0319415 elbow - this goes through the outer exhaust cover.
0321885 nipple - this goes through the lower cowling.

A hose connects the two.

 

[OptsyEagle]

Re: Intermitent water spray

Joe Reeves Comments: "Perhaps the water pump plate to lower unit and impeller housing to plate wasn't sealed properly.

Use Boat Armor Sealer 1000 as a sealer, available at automotive stores and possible Wal*Mart, K-Mart etc."



I can see sealing the plate to lower unit, but isn't it a concern when sealing the housing to plate, that some of this material may end up squeezing in with the impeller, and if so would it cause any damage.

Plus, I was told that OMC Sealer 1000 was the same as 3M-#847, is this true?

 

[OptsyEagle]

Re: Intermitent water spray

In addition to my above question about sealers, approximately how long do you let this stuff set before you can test the water pump?

 

[Joe Reeves]

Re: Intermitent water spray

By the time you get the rest of the engine together, the sealer is set.

There's no chance that the sealer will damage the impeller.

The top water tube grommet, under the powerhead, has a habit of swelling and restricting the water flow.

 

[OptsyEagle]

Re: Intermitent water spray

Does this swelling fix itself, because I too have seen this intermitent water spray? It may start out with a good spray, then change to a dribble and back to a medium spray and that type of thing. I always thought it was the thermostat cycling on and off, but from what I hear that may not be it.

 

[ezeke]

Re: Intermitent water spray

Here's a link that might help the discussion along:

http://www.sschapterpsa.com/ramblings/water_circulation.htm

The water flow diagram shows where the tell tale [overboard water indicator] is on a lot of models. It is better to run the line from the top though:

http://www.sschapterpsa.com/ramblings/OB%20images/water_passage.jpg

Click the diagram to enlarge it.