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115 Johnny power head replacement

H

hiway

Member
Howdy fellers....noob here and it looks like a place I'm gonna enjoy. Long time boater and currently have a 98 Crest pontoon with a 115 Johnson .....and a 75 CeeBee Avenger jet boat.

My quest is: Replacing power head on my 98 115 bubble cross flow.....are there any "special" tools needed? Got manual and rebuilt head already....haven't turned the first nut yet though.
Any and all tips would be welcome! Old hot rodder but this is my first outboard or 2stroke adventure....
 
No special tools required to swap out a powerhead.-------Lifting the powerhead straight up may require an adapter to the crankshaft thread.
 
Patients i have....sorta! lol
Cool that no special tools are needed.
Looking ahead there are at least 3 things that i am concerned with: Removing flywheel, timing motor (prefer static time it first), and sync'ing carbs
of course that's assuming all comes apart easily
 
rosie motor.jpgwell gentlemen, it's offt!
 
i tried posting picture of damaged piston but won't load. It is flaked/beat up. Someone suggested the ethonal gas and moisture was the cause. My barge usually stays in a slip at the lake and probably had some 10% E gas in it.

I did buy a manual and water pump kit. Thermostat and fuel system should be gone thru also huh?
 
Broken piston rings / damaged piston is very common on these motors.----Possible cause is wrong propellor for the boat that the motor is on.--See this damage all the time.
 
Well guys she's alive. Engine ran great....starts easy, idles smooth, moves out fine. Guess my previous power head was weak because it never (in my 4yrs as owner) ran this smooth.

Now the issue...school me in the cooling system please. I replaced the water pump impeller with a kit. Seemed fine using the muffs...seemed fine at first while on the maiden voyage. Then the water "pee'ing" went to a drizzle....and i put boat in the slip. Engine wasn't hot cause i could hold my hand on heads. Did i mess up an o-ring putting foot back on? Let it set a few minutes and restarted. Took a few seconds to start pee then water starts coming out two rear holes at top of foot (half inch holes below power head) and pee slows to a trickle. And where is the thermostat? truely a rookie here....
 
There are 2 thermostat located under the exhaust bubble at the back of the exhaust housing.-----Post #6 / 7 mentions thermostats.----------Would have been an easy inspection when powerhead was off !!!
 
monitor oil? i mix it a little richer than 50 to 1.

Yes i should have looked at thermostats with power head off... I actually never realized that's where they were at that time. My bad.

Does ALL water exit thru the pee tube?
 
kimcrwbr1 said:
normally the telltale pulls water from the exhaust cover to tell you the powerhead is charged with water. Most of the water is dumped out the prop with the exhaust take a thin wire and ream out the telltale fitting on the cover and on the engine. The fitting on the engine may need to be removed to clean it good. Put your new thermostats in and then in a barrel of water flush it out good if you can with saltaway in the barrel. I believe the water coming out the exhaust reliefs should be hot when the thermostats open. Put new thermostats in and any parts necessary and flush it with saltaway and see how she does?
Click to expand...
dont rule out that the tell tale is plugged especially after a rebuild could have a piece of gasket material stuck in hole
 
so at idle...seeing water coming out of the two small ports at top of foot housing is a good sign it's getting water but possibly the telltale fitting is plugged? Telltale seemed fine at first part of outting (10minutes or so) and then dwindled to almost nothing
 
Did you replace the water deflectors in the block ?----2 on each side.----You should inspect the 2 thermostats and the 2 poppit valves in that housing !!!
 
i bought a complete power head (less carbs and ignition) and swapped it in place of my dead one.....then pulled foot and replaced water impeller. No looking at deflectors nor thermostats
 
since heads and all were in place....i'll assume the deflectors are there.

anyone's thoughts on the water coming out of the two small ports (exhaust?) at idle while it's barely pee'ing? Could i have screwed up something during water pump change?
 
the previous head always had strong pee at all times...idle included. Same thermostats as this new head (reman) and she was barely pee'n after a short first cruise. I did change impeller....hopefully correctly
 
so I've thought over my rebuild and think i've screwed up one of two ways....either i didn't include the bushing/seal at pump that connects to the tub (can't remember seeing it) OR i put the impeller in with the blades bent the wrong direction
 
Well the verdict is......trash. Yep, pulled lower unit off and pump apart and found nothing. WTCrap? So I pull the telltale off...the 90degree fitting inlet was full of some kinda plastic (dark) looking stuff. So re-assembled everything and hopefully will have time this evening to start it. Found plastic drum to cut top and put foot in instead of using muffs.
 
We boat in the salt and sandy areas, can't tell you how many times I have had to clean out the tell-tale hole due to a small pebble or some other crap making it's way thru the whole system only to get stuck there. An old marine mechanic told me a long time ago that usually about 85% of the time the motor isn't "peeing" out the tell-tale, it's due to that little hole getting clogged up. Usually a simple fix. Glad you were able to figure it out!

Dave
 
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