Starting again, '80s Johnson 115hp

nswtex

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Jul 12, 2009
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17
I just got the boat out of the shop and am having these issues. This is a presumably 1982 model Johnson 115. It had been out of the water for three years. However, it was started occasionally on muffs It went in to the shop and had a tuneup, waterpump and some housekeeping work done as well as a pump out. Well I think they pumped out the old fuel.

Motor starts fine, I let her warm up and then take her out, after about 10-15 minutes of running I get little surges, then it cuts out all together. I was able to start her back up and limp back to the ramp but it got increasingly difficult each time it died and on start-up it blew more and more white smoke each time.

I can not recall if the bulb stayed firm, but I did have a full tank of fresh 97 octane?

Thanks for the help guys.
 

kenmyfam

Supreme Mariner
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Aug 10, 2006
Messages
14,385
Re: Starting again, '80s Johnson 115hp

Did the carb's get a service ???
Post your model number (port side of the transom bracket) to give everyone a better idea as to which motor you have.
 

Silvertip

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Sep 22, 2003
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28,758
Re: Starting again, '80s Johnson 115hp

1) Why 97 octane fuel. Waste of money, not necessary, and slower burn than regular so loss of power on top end. High octane fuel is required in high compression engines to avoid detonation. You do not have a high compression engine.
2) White smoke and engine stalling is never good. Does your overheat alarm work?
3) This can be a blown head gasket (water leaking into the combustion chambers) due to an overheat.
4) Was the water pump impeller replaced since you've owned the boat. (Possible overheat).
5) Stuck thermostat or bypass valve. (possible overheat)

Remove the plugs and check them carefully. If they look like like brand new, but really aren't, that's a since of being exposed to very hot water (as in a head gasket leak).

A compression check may show which cylinder(s) are leaking.

Verify that the alarm system is working.
 

ezeke

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Sep 19, 2003
Messages
12,532
Re: Starting again, '80s Johnson 115hp

Agree with Silvertip, sure sounds like overheat/ blown cylinder head gasket.

What are the results of your compression test?
 

nswtex

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Jul 12, 2009
Messages
17
Re: Starting again, '80s Johnson 115hp

I am going to call mechanic back today that I just picked up from. They did do a compression check before service and it was good. The water pump was replaced. At least I paid for it to be replaced lol. The 'pee' hole had a constant stream of water the entire time engine was running. The smoke I mentioned was only at startup and once it puffed out there was no visible smoke at all.

Spark plugs were replaced as part of tuneup so may be hard to tell if I were to check them?

I will update this afternoon with model number and what mechanic said.
 
Last edited:

SparkieBoat

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Aug 17, 2009
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3,643
Re: Starting again, '80s Johnson 115hp

try pumping fuel bulb and see if engine temporary surges, this would indicate fuel pump or fuel line issues. check all fuel line connections and pick up tube in tank as well as tank vent...you need to eliminate fuel problems first then move on to compression and ignition test..
 

nswtex

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Jul 12, 2009
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Re: Starting again, '80s Johnson 115hp

Soooo..

If a mod can move this to the stupid human tricks section I guess it belongs there now.

My mechanic, who just gave me the boat back like 48 hours ago, says my issues may have something to do with putting a full tank of fuel in the boat and not adding even a drop of oil to the mix. :(

I was thinking about that before I picked her up and it totally left my head until he mentioned it on the phone and I almost threw up. I will let you guys know what happens. This is my first boat, I grew up with friends with boats and spent quite a bit of time on the lakes but never in the maintenance portion of this lifestyle. This is my first ,and hopefully last at least for a little bit, bonehead move. I am so embarrased I want to wear a disguise to drop the boat back off to be checked over for damage. :cool:
 

SparkieBoat

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Aug 17, 2009
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3,643
Re: Starting again, '80s Johnson 115hp

you can get a good used 80s model 115 for around 1K..I would not even mess with the one you got.
 

Cthom5436

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Sep 20, 2007
Messages
29
Re: Starting again, '80s Johnson 115hp

I'm not a mechanic, but if you ran the cyclinders dry shouldn't you double the oil mixture, like you are breaking in an engine?
 

SparkieBoat

Captain
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Aug 17, 2009
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3,643
Re: Starting again, '80s Johnson 115hp

doubling the oil will not fix damage to pistons/crankshaft
 

kenmyfam

Supreme Mariner
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Aug 10, 2006
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14,385
Re: Starting again, '80s Johnson 115hp

Sounds like you fried it !!:eek:
Hopefully not though. Let us know.
 

tashasdaddy

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Nov 11, 2005
Messages
51,019
Re: Starting again, '80s Johnson 115hp

are you saying the Mech filled the tank, and did not ad oil. if so, i think he has some responsibility in this.
 

nswtex

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Jul 12, 2009
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Re: Starting again, '80s Johnson 115hp

Unfortunately I am the newb that failed to remember that oil needed to be added. I understand that this has the potential to be a very costly mistake. Along with the fact that I could have been left stranded on the lake, even though I didnt leave the cove.

The mechanic and my boating friends here are optimistic about there being very little damage due to the fact that I only ran the boat for about 15-20 minutes before putting her back on the trailer and the fact that she was still idling fine when I finally shut her down. And as for the white smoke he said since it wasnt plumes of it and just puffed out on startup and then disappeared it was probably just unburned fuel from the trouble getting it to fire up.

I will update after he looks at it. Usually when I learn a lesson the hard way, especially an expensive way, I am very unlikely to repeat it.

Right now the wife and kids are pretty down after I explained to them that this may be the end to their boating dreams until I can arrange to get a new motor because daddy made a big boo boo before they even got to see it run for themselves. OK I feel sick again.
 

ezeke

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Sep 19, 2003
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12,532
Re: Starting again, '80s Johnson 115hp

It's good shop practice to replace the cylinder head gaskets after an overheat. As a minimum precaution, you need to at least re-torque the cylinder head bolts.

While replacing the head gaskets you can inspect for possible damage and check the water passage deflectors.
 
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