1973 Johnson 115

[bobsquatch]

Well last night I bought a 73 Johnson 115 to replace my blown 1990 88 SPL. Compression is good at 112 112 119 and 114. The lower unit oil is a little cloudy but still looks like oil not milk. The transmission is silent in forward and reverse and it seems to be in decent shape overall and runs fairly well at Idle and revs up fine on the muffs. The only obvious problem is that it will not start on it's own from the key and must be jumped at the starter to fire it up. Could be anything at this point but I bought it and took the controls with me and we will see how it works out. I only paid $270 for this motor about half what it will cost me to rebuild the 88.

 

[emdsapmgr]

Check the main fuse in the wire harness by the starter solenoid. If that fuse blows, the starter will not work.

 

[bobsquatch]

The saga continues so today I pulled the 88 off my boat and replaced it with the 115 and fortunately the controls are identical and functioning perfectly for both motors. I did however run into the same problem with my old controls that were in the boat the 115 will not start under its own power when you turn the key on the choke solenoid activates and everything is ready to go but it will not crank from the start position just like the original controls I tested power to the solenoid and found it did not click or anything when I turn the key although it did get 12 V so I assumed the solenoid is bad and I pulled the good one from the 88 in swapped it out. Now that I have installed a known good solenoid in place of a questionable one I get nothing. When I hook up the battery terminals in turn on the key the choke solenoid no longer activates and nothing happens when I turn the key to the start position. I swapped out the battery terminals positives from one side to the other and also the ignition and starter wires and still nothing. Any ideas what I may have done to kill the power to this Engine please feel free to chime in. Anyway it got dark on me so I quit for the evening I will probably wake up in the middle of the night and realize whatever it is that I have done to stop this engine from starting. Anyway I ordered a service manual for it this morning as well as a spacer for the prop and I am sure whatever else is going on will get resolved fairly easily if I didn't mention it earlier this motor has clearly been rebuilt as there is foreign gasket material all over it and that is probably why the compression is so high.

 

[bobsquatch]

Thanks emdsapmgr I will check the fuse next time I am working on it. (didn't even know it was there) It looks like rain here next weekend so no hurry as my wife's car needs work too. The manual should be here in a week or so and that will help tremendously. If anyone would like to chime in on this motors foibles please feel free. I would love some salty perspective.

 

[bobsquatch]

For a little perspective I bought a 1970 Chrysler Commando boat with a blown 1990 Johnson 88SPL. I have found this replacement 1973 Johnson 115 which fit up perfectly and I am now chasing off the gremlins. The hull is only good for 90HP so of course when I am done ironing out this 115 into a working replacement I will take it to my buddy's aqua dyno and adjust the throttle stops at 89.999999999999 HP. This little 1,000lb boat did ok on a blown 3 instead of 4 cylinder 88 horse with the throttles opening about 80% Roughly a 55HP setup. Cant wait to see what 90 HP does! I hit 30+ MPH before. I will post result with 90HP behind a 19 pitch prop.

 

[emdsapmgr]

The 73 engine was rated at the crankshaft back in then. When you rate that 73 by today's standards (propshaft rated) your horsepower would go down due to the driveline friction, or maybe 10%-12%. Unfortunately, the hp rating on the engine is what catches everyone's eye-and that's the 115 stamped on the top of the powerhead.

 

[Faztbullet]

Sounds like the safety switch on throttle linkage is out of adjustment. If throttle is advanced to far it breaks ground to solenoid and wont allow starter to function...

 

[bobsquatch]

I unplugged the safety switch to see if that would help even though it appears to be adjusted correctly and that didn't work. I am sure it is something simple like that though.

 

[bobsquatch]

The 73 engine was rated at the crankshaft back in then. When you rate that 73 by today's standards (propshaft rated) your horsepower would go down due to the driveline friction, or maybe 10%-12%. Unfortunately, the hp rating on the engine is what catches everyone's eye-and that's the 115 stamped on the top of the powerhead.

Either way it's way more hp than I need. I bought the 115 in the hope that it was more similar to my 88 than it turned out to be. Speaking of that the 1990 88 was probably rated at the crank too right? Any way you look at it I will nearly double the power I was getting with my sick 88.

 

[racerone]

The 73 model V-4 motors are " unique " as many / most internal powerhead parts will not fit the 1972 or 1974 model years.

 

[tblshur]

bobsquatch, dont mean to be bearer of bad news but if you reverse battery terminals , it will blow rectifier. dont ask how i know. ha ha :joyous:

 

[bobsquatch]

If you reverse the battery terminals sure. You don't mean connections on the solenoid do you? I wouldn't think it would matter either way connecting the solenoid because there is no ground. Also at no point when connecting the battery terminals back to the battery I did Not Ever get any kind or current draw or sparking.

 

[bobsquatch]

On these motors is it common to get more water out of one of the exhaust ports and than the other once warmed. up my starboard side spit pretty good in the Portside barely spit at all.

 

[F_R]

I unplugged the safety switch to see if that would help even though it appears to be adjusted correctly and that didn't work. I am sure it is something simple like that though.

"Unplugging" the safety switch would make it NOT work. If you want to check that part, ground the wire that goes to the safety switch. The safety switch grounds one of the small posts on the solenoid when it is safe to start. The other small post receives 12V from the key switch when you turn it to start position. Makes no difference which is which. If you are not getting that 12V in start position, my guess is the neutral start switch in the remote control is bad......OR it is not in neutral.

 

[bobsquatch]

Thanks F_R. I did manually put the linkage in the neutral position and look that the switch was being oriented properly in that position so I am confident it is in neutral also this is the control box I had running my 88 and it did not have these issues. this particular motor was having the Exact same issue with the control box that came with it so I am also reasonably certain it's in the motor not the controls. I am betting the fuse I was told to check is the culprit here now but I wonder why it would blow I will know more when I get home this evening.

 

[F_R]

Well then, it's time to stop guessing and properly test stuff. When you turn the key to start position, do you have 12V on one of the small solenoid terminals, and zero volts on the other? That is what it should be. The zero V is because the safety switch is closed (grounded). If you are not getting the 12V, the problem is ahead of there. The circuit is battery cable/small wire to fuse, to fuse, to ignition switch, to neutral start switch, and back to the small solenoid post. In between you have two passes through the big cable connector plug.

I trust you are sure the battery cable connections are clean and tight. (?).

 

[bobsquatch]

Thanks F_R. Yeah I just ran out of time last night after installing the motor on to the hull and connecting everything I started having these little problems and then I ran out of daylight I will be doing a much more thorough investigation when I get home this evening. The battery is new and charged and The cables and all other connections I have made are spotless. I am reasonably certain it was the solenoid that was bad and I must have blown a fuse when I swapped it out.

 

[bobsquatch]

Well that is odd. the 9A fuse is good but I have 0 volts at the main battery terminals on the engine. I have 12.7v at the battery so it must be in the control box???

I will check the manual for the 88 and see about the control box wiring.

 

[bobsquatch]

Good news. After determining there is no major power running through the control box I noticed the brand new battery cables at the battery don't match the older but good looking cables at the motor. I tied rope to the cables and started dragging them out of the hull... pop! The connection on between new and old ground cables had failed. Cleaned up, re crimped, sealed up and WALA!!! All is well again. Checked the other connection and routed them back to the battery. Still wouldn't crank from the key so I grounded the neutral safety switch and she fired right up. All is well for tonight. Thanks for all the help so far.

 

[pro-crastinator]

I just re read this post (new boat) and the last, and just want to make a comment on the lower end lube.
I know its a little off topic - but it may need to be said.
The synthetic lube you are using was not formulated to react "well" from water intrusion.
The marine grade lube is designed to take on water and still perform its job.
Just wanted to get this out there.