1981 Johnson 115 slow water stream

81manatee

Seaman Apprentice
Joined
Aug 1, 2017
Messages
32
I have never messed with an outboard before. I've been working on the ignition system and just got it all working right I think. The engine was idling on the muffs and I did not like the very slow stream of water coming out of the rubber outlet hose. It ran for maybe 5 to 7 minutes. The flat plate between the heads was not hot or even warm to the touch. The heads were warm but not hot. There are two hose elbows connecting from below the engine to the heads. Neither felt like much water if any was moving through them. The parts listings show thermostats on this engine. How long does it take foe them to open? Will the pisser flow slowly until they open? When I say slowly I mean more than a dribble but not by much. Are there thermostats on this engine?

Input needed and appreciated.
 
Last edited:

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,033
There are 2 thermostats on the engine.---------And the thermostats have nothing to do with the flow out the telltale hose !
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,598
Run a piece of wire or monofilament up into the tell tale (weed whacker line works well). You probably won't get up to temp on muffs -- can't really test water pump or circulation that way. Can dip it deep in a barrel to test, if not close to the lake. (Think plastic trash can.) Has to be 4 or 5 inches above the water pump, not the intake -- idle or high idle only if in a barrel.
 

interalian

Commander
Joined
Jul 23, 2009
Messages
2,105
The 'pisser' stream taps off the water system at its coolest part, where the water enters the exhaust cover. Volume does not change with thermostat operation.
 

81manatee

Seaman Apprentice
Joined
Aug 1, 2017
Messages
32
There is a length of rubber vacuum line stuck on the outlet fitting. It's clear of obstruction. Are you suggesting to stick the trimmer lime into the fitting where the hose attaches?

The thermostats won't open on the muffs. Im guessing this is why I felt no flow through the hoses connected to the heads.

What controls the flow of the pisser tube? Rpm?
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,033
The more rpm the more output from the pump both in volume and pressure.
 

81manatee

Seaman Apprentice
Joined
Aug 1, 2017
Messages
32
Slow stream can be caused by clogged system or deteriorated impeller. Is this right?

I watched a video on water pump rebuild. Seems involved but straightforward. Is dropping the lower unit and performing a water pump rebuild a bad idea for a shadetree mechanic? How much of a pain is it to seal up and reconnect the shift linkage?
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,033
If you do not know the age or condition of the impeller you should install a new one ASAP.-----Not hard to do.
 

trailking82

Petty Officer 3rd Class
Joined
Dec 31, 2010
Messages
84
Its a fairly basic chore. Not too big that an average mechanically inclined person couldnt do.
 
Last edited:

interalian

Commander
Joined
Jul 23, 2009
Messages
2,105
Yes, pretty easy. Just be sure you do not rotate the shift rod while you have the leg off. About the hardest part is getting the shift pin/screw back in when you put the leg back.
 

81manatee

Seaman Apprentice
Joined
Aug 1, 2017
Messages
32
Service records from the previous owner show that a water pump kit was installed in February of 2017. I'm not even sure the boat was put in the water bewteen that & when I got it. I've ran the boat maybe 5 times. There are less than 5 hours of running time on the water pump. The last time I ran it, I got in some shallow water and started kicking up mud, while circling the launch waiting for my turn, then I cut the motor off right afterwards at the dock. Could some part of the system be clogged up with mud? Otherwise, the only other thing I can think of that could have deteriorated the impeller is that I cranked the motor around with the kill switch off a few times while troubleshooting the ignition system, and forgot to hook up the muffs first. Could this have trashed the impeller?
 
Last edited:

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,598
Mud/sand can chew up an impeller big time, and can clog up water passages. It's true you shouldn't crank it over dry, but will guess most of us have checked for spark or done compression checks without thinking about the lower unit.

I think I would test the motor with the lower unit in a barrel or in the lake -- water needs to be a few inches above the water pump (which is above the intake). Just dunk it about half way up the leg to be safe (floods the lower unit too, providing back pressure for testing ignition/compression/carb.) There's not much you can do on muffs in the way of testing the water pump.

If operation is good (pumps water, temp remains good), let it idle for a bit to clear it out.
 

Fed

Commander
Joined
Apr 1, 2010
Messages
2,457
Have you got the nipple fitted in the lower cowl, if you're only using the rubber hose without the fitting it will not squirt as well.
 

81manatee

Seaman Apprentice
Joined
Aug 1, 2017
Messages
32
I will have to find a barrel. The lake is about an hour away, and the next time I go, we're fishing, dangit!! :)

The 90 degree fitting on the engine has a hose hookes to it that runs out through the lower cowl and sticks out about 6". The previous owner put it on there so he could keep a close eye on the pisser while running the boat.
 

oldboat1

Fleet Admiral
Joined
Apr 3, 2002
Messages
9,598
Better to watch the water in front of you :) (temp gauge would be a better choice, if you feel it needs checking). But that little fitting for the tell tale should improve the way it works, and make it easier to see. (believe it would improve pressure in the passages too -- forcing water up and around instead of down and out. Not sure of that...)

You need a big plastic trash can -- put a drain at the bottom, so you can empty it to move it out from under the leg. Use the jack on the trailer tongue to get the depth right. Sounds a little hokey, but works -- idle or fast idle only; good idea to keep the hose running to keep the level up.
 
Top