1978 115hp Johnson outboard newbie question

Bob Bismal

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Joined
Sep 25, 2005
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14
Howdy, First a little history so you know what a newbie I really am. I've only been in a boat 2 times in my life and those were about 20 and 25 years ago. Now I've got 2 boys and really want to take them fishing. I live on an island (with three roads going over the canals) and we've been just about the only people in this city without a boat sense we moved in about 7 years ago.<br /><br />Well now I've bought a boat. It's a 1978 Starcraft Holiday Closed bow, with a 115hp Johnson outboard. Everything on the boat is original and in pretty good shape. I paid $1900 for it. Good price? Now for the real questions.<br /><br />1. I know you need a battery to start the motor, but do outboards need a battery to run?<br /><br />2. It came with a Humminbird 4X6 fish finder and a radio. Should I worry about killing the battery if I run these while the motor is running? Or with it off? As far as I can tell the manual that came with the motor says it has an alternator, will that charge that battery / batteries?<br /> <br />3. I took it out yesterday for about 4 hours and when I got it home and pulled the bilge plug it had about 5 gallons of water come out. The bilge pump wasn't working, and I plan to fix that before I go out again. I's that much leaking normal or something I should fix asap?<br /><br />4. The tachometer doesn't work. Is that a big deal? I'd kinda like to have some idea what the motor is doing.<br /><br />5. Many more questions to come, just can't think of them right now so just tell me anything and everything a newbie might ask. BTW, when I took it out, it ran awesome. Nice, quiet smooth ride, started right up and went like a bat out a hell.<br />Best pic I've got so far<br />
boat.jpg
<br /><br />Thanks in advance for all your help.
 

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Re: 1978 115hp Johnson outboard newbie question

First off you need to find out how that water is getting in there. 5 Gal is too much. You need to keep a battery connected to the motor at all times. Check your charging circuit. Measure the voltage with the motor off, then while in the water increase the RPMs to about 2K and you should see an increase in voltage. If you do not see an increase, change your rectifier. That could also be the reason your tach doesn't work. Good luck and welcome to iboats.
 

Tacklewasher

Lieutenant Commander
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Sep 18, 2002
Messages
1,588
Re: 1978 115hp Johnson outboard newbie question

I've got the same boat (except mine is blue) and it looks like the same trailer ;) <br /><br />I'd like to say that's too much water, but I'm pretty sure I'd get that out of a 4 hour run as well. I have a winter project in mind to fix it, but I think it is just a case of an old hull and a lot of loose rivets. Get a working bilge pump, with a auto float, and save finding it for when you decide to pull the floor up. Not everyone will agree, but I think you will be chasing your tail trying to sort out leaks with the floor still in.<br /><br />I had my rectifier go (actually one wire broke) and it prevented charging AND made the tach not work.<br /><br />You want to keep the motor connected to the battery to charge it. It will run without, but no reason to.<br /><br />A fish finder will take a long time to run down a battery. I leave mine on.<br /><br />Any idea how fast you got the boat going? DO you have a speedo (or better a GPS)?<br /><br />I love my boat but am tracking down a couple of motor gremlins. When I find them, fishing season will be over (water gets kinda hard here in the winter) and am pulling the floor out. My plan is to tighten up the loose rivets and then paint the inside bottom of the boat with stuff you would paint on the roof of an RV. It's cheaper then truck bedliner, more flexible and will give me a nice waterproof seal insie the boat. I expect this to solve 90% of my water issue. A new floor and I have a boat that's as good as new.
 

Bob Bismal

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Joined
Sep 25, 2005
Messages
14
Re: 1978 115hp Johnson outboard newbie question

The guy I bought it from said it went about 42mph. I'd buy that. There is a road on Grosse Ile that runs along the water and the speed limit is 35. I was keeping up with the cars on the road (I'm sure they were going a little fast). <br /><br />I'm thinking about doing the same overhaul on mine this winter also but using a product called GLUVIT on the inside and bottom of the hull. After I tighten up the rivets and replace the pop rivets some retard put in it. I'll also be getting rid of that lovely orange color asap :D .
 

Tacklewasher

Lieutenant Commander
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Sep 18, 2002
Messages
1,588
Re: 1978 115hp Johnson outboard newbie question

Hmmm. That Gluvit may be a good idea as well. Just remember to leave the drain's in the ribs free of stuff or water will sit instead of draining.<br /><br />I can't seem to get mine over about 35. 42 sounds better.<br /><br />I really like my blue. Guess I should post a picture of it.<br /><br />One other thing I'm thinking about is converting to an open bow (hey, I already replaced a I/O with an outboard, should be able to open up the bow) and put in a casting platform.
 

Cricket Too

Lieutenant Commander
Joined
May 14, 2003
Messages
1,732
Re: 1978 115hp Johnson outboard newbie question

You may want to think about replacing those trailer rollers with bunks instead. The rivets in aluminum boats don't like those rollers, tends to put pressure on them and loosen them up when it rolls off and gets winched back on. At least that's what I've been told.
 

Bob Bismal

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Joined
Sep 25, 2005
Messages
14
Re: 1978 115hp Johnson outboard newbie question

Forgot to mention. When I first put it in the water, I backed up and went about 50' at very slow speed (no wake zone). Then a buzzer started going off. It sounded like it was comming from in the dashboard or in the Throttle Assembly / motor control (not sure what the correct name is). <br /><br />Anyways I shut it off for about 30 seconds and it fired right back up and never heard the noise again even when I was putting back to the dock in the no wake zone again. Any idea what the heck it was?
 

Marc J.

Petty Officer 1st Class
Joined
Mar 16, 2004
Messages
267
Re: 1978 115hp Johnson outboard newbie question

I'd bet it was overheating Bob. Changing the water pump impellor and thermostats is advised every 2-3 years. Another possibility is that the thermostats were recently changed and the ones used lacked the tiny hole that lets some water past. This creates a air pocket and results in what you experienced. Filing a small notch in the edge of each popet valve is advised in this case. Do a search for V4 thermostat replacement. Also buy a manual, the factory J/E service manual is the best.
 

Bob Bismal

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Sep 25, 2005
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Re: 1978 115hp Johnson outboard newbie question

Well I took it out again for about 4 hours with no beeping from anything. Should I even worry about what ever that beep was?<br /><br />When we were first going out the boat was leaning to the left side of the boat quite a bit. It cleared up when we went faster and didn't do it at all on the way back. Could this have just been the wind?
 

Solittle

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Joined
Apr 28, 2002
Messages
7,518
Re: 1978 115hp Johnson outboard newbie question

Bob - If you don't know the history of the engine it is good practice to change the water pump, thermostats, gear oil and plugs. And yes I would worry about the beep until you do the water pump & t-stats.
 

Bob Bismal

Cadet
Joined
Sep 25, 2005
Messages
14
Re: 1978 115hp Johnson outboard newbie question

Is it saft to run the motor with a pair of rabit ears hooked up? How long can the motor run with them? How long should you run it to flush out the system?
 

Tom Scully

Petty Officer 2nd Class
Joined
Oct 14, 2003
Messages
154
Re: 1978 115hp Johnson outboard newbie question

You can run the motor on the "rabbit ears" as long as you don't go above fast idle speed.<br />Run the motor long enough to get the thermostats to open plus 5 minutes.
 

Solittle

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Re: 1978 115hp Johnson outboard newbie question

What kind of water are you running in in SE Michigan ???? No need to flush unless you run in salt.
 

Bob Bismal

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Sep 25, 2005
Messages
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Re: 1978 115hp Johnson outboard newbie question

I'm right on the line between Detroit river and lake Erie. The water around here is only about 2' deep and I turn up quite a bit of dirt on the way to and from the dock. Lots of weeds also.<br /><br />btw, how do I know when the thermostat opens?<br />What's the cheapest place to get a service manual? Seem like there would be a pdf version out there somewhere.
 

MCM

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Basscat 1

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Feb 11, 2005
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444
Re: 1978 115hp Johnson outboard newbie question

Fix the tach, its the most important instrument you have.<br />The rpms should be 5800 at wide open throttle.
 

Bob Bismal

Cadet
Joined
Sep 25, 2005
Messages
14
Re: 1978 115hp Johnson outboard newbie question

I've found a 1976 115hp service manual. Is that the same motor as my 1978 115ph? Is there an easy way to tell?
 

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: 1978 115hp Johnson outboard newbie question

The 1976 115 is part of a series from 1973 through 1976. There are way too many differences for the manual to be very useful for your 1978 115.<br /><br />The 1978 Evinrude manual is the same as the Johnson, except for cosmetics, so either one will do.
 

Bob Bismal

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Sep 25, 2005
Messages
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Re: 1978 115hp Johnson outboard newbie question

So a 1977 - ? year are pretty much the same?
 
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