1998 25hp 3 cylinder Johnson

[cgraham]

Hey guys got a question. I have searched the internet, and asked around about my 1998 25hp 3 cylinder Johnson with no real answers. I am curious about the motor, and wanted to get opinions about it. Some people I talk to say it was the strongest and best 25hp Johnson ever made, while others say its junk. So, any information you can throw my way would greatly help me out.

I haven't had any real trouble with the motor, just changed the lower unit gear lube last night (02/07/15) and didn't notice any metal shavings on the magnet at all, and no signs of water leaking in.

* Here is something that does puzzle me though! When I first get to the ramp and after hitting the primer bulb several times the motor is unusually hard to get cranked, but once it hits there is no problem with it running at all. There are a couple spots close to the ramp that I always stop at and are with 1 1/2 miles from the ramp and usually takes me about 45 minutes to an hour to cover. Then, the same thing again, the motor won't start without the choke on.. Any suggestions on what it might be, or something to check? Or, is it just one of the motors that you have to choke every single time? Thanks Guys..

P.s. I have changed out all the fuel lines to the new ethanol resistant ones, new primer bulb, and replaced the fuel filter and had the fuel pump checked..

 

[JoshKeller]

great motor if the oil mixer is removed. I had a 2001 35 hp 3 cylinder. unreal torque. is your quick start functioning properly? Mine would take about 3 revolutions to fire up first thing with the choke pushed in. after fishing an hour or so, i usually would have to choke it. Have you verified the thermostat is getting the motor up to temp?

 

[cgraham]

Yeah the oil tank has been removed, and I run 50:1 in it now. As far as I know the thermostat is good, and the quick start is good. Usually on the 7th or 8th turn she will fire up.

 

[JoshKeller]

id go through all three carbs (i found it easier to just replace the orifice jets than clean them) and do a sync and lync to start.

 

[Pappy]

Josh is leading you in the right direction.
That is one of the last engines produced by OMC that still had a choke instead of a primer system.
Pull the air silencer cover and visually check and see if the choke blades completely close when pulling the choke lever. If not, correct.
As far as the engine goes you can do a search in this forum for some answers I have provided to people in the past.

That engine (the 25hp) was originally developed as a 500cc racing engine for European racing by OMC. Although that class never developed, the engine was already designed and being produced. Several engines were sent over the pond already in anticipation of the class. The racing versions had a different intake and carburetion set up among other big changes vs. the consumer version.
It was deemed too expensive in the American market to compete with the 2-cylinder version. Back then OMC was selling horsepower per dollar and that engine was expensive to produce so the margin of profit was not there. It never got advertised but the dealers knew about it and ordered it anyway.
In short, you have one Hell of an engine. Service parts are still available for it but if I were you I would pick up carb kits and a water pump or two along the way.
I currently have (4) of these engines and purchased a blown up one for spart parts as well. It is probably one of the most potent of all 25hp engines ever produced. It will typically turn a 15" pitch propeller on boats that normal 25hp engines will turn a 13" pitch.
I would increase your oil ratio on that engine to around 40:1 just to make sure you get the most life you can out of it. Not many of these around.
How's that for information?

 

[cgraham]

Josh is leading you in the right direction.
That is one of the last engines produced by OMC that still had a choke instead of a primer system.
Pull the air silencer cover and visually check and see if the choke blades completely close when pulling the choke lever. If not, correct.
As far as the engine goes you can do a search in this forum for some answers I have provided to people in the past.

That engine (the 25hp) was originally developed as a 500cc racing engine for European racing by OMC. Although that class never developed, the engine was already designed and being produced. Several engines were sent over the pond already in anticipation of the class. The racing versions had a different intake and carburetion set up among other big changes vs. the consumer version.
It was deemed too expensive in the American market to compete with the 2-cylinder version. Back then OMC was selling horsepower per dollar and that engine was expensive to produce so the margin of profit was not there. It never got advertised but the dealers knew about it and ordered it anyway.
In short, you have one Hell of an engine. Service parts are still available for it but if I were you I would pick up carb kits and a water pump or two along the way.
I currently have (4) of these engines and purchased a blown up one for spart parts as well. It is probably one of the most potent of all 25hp engines ever produced. It will typically turn a 15" pitch propeller on boats that normal 25hp engines will turn a 13" pitch.
I would increase your oil ratio on that engine to around 40:1 just to make sure you get the most life you can out of it. Not many of these around.
How's that for information?

Thank you Sir! Thats was what I was really wanting to know - general back ground on the motor. Like I said, I havent had any problems out of the motor at all. It came with the boat when I purchased it, and I was able to speak with the previous owner who told me he got it to replace a stolen motor off his boat. He said it was too much for him, so he just sold the entire rig.

I have been noticing some unburnt fuel & oil mix from the motor after I put it back in the garage, running down off the skag, which takes me to my next question if you can help me out on it...

I have been told that this it typical for these engines, and that its just unburnt fuel & oil mix with nothing to worry about.

My work schedule only allows me to fish maybe 3-4 times a month. At the moment, I am using both stabill red & startron mix with my gas since 100% ethanol free gas is hard to come by here in east tennessee. I am worried about gumming up my carbs, and am looking at maybe seafoam..

If I cut out all stabil & startron additives and just go with seafoam would that be a better choice? I have had several old timers tell me half a bottle of seafoam in a 6 gallon tank is all you need, why waste money on the stabil and startron.. Also said seafoam will treat that johnson right.. Whats your view on it? And THANK YOU ONCE AGAIN!

 

[Pappy]

If you are fishing that many times per month then cut out the additives altogether. Not needed. If you choose to continue, just use the startron product mixed to their directions. Never try to bring back old fuel by putting new on top of it or adding a ton of additive. Get rid of it and start fresh.
I too only use fuel with no alcohol in my outboards and lawn equipment. Less issues....more free time!
Yes, the drool is normal. The more idling you do prior to shut down the more drool your engine will produce. You may also be a touch rich but if you like the idle quality that's okay.
What part of East Tenn. are you from. Reason I ask is that there is another guy that did the same job I did up in Smyrna that would probably look at your engine for you if you are in the least concerned about it.

 

[DaleH]

If you choose to continue, just use the startron product mixed to their directions.

FYI, to save $$, one can buy their 'diesel' formula (same price as the gas version), but it is formulated at twice the concentration, so just use 1/2 the stated amount (on the bottle) in your mix.

You can confirm this for yourself by comparing their packaging and the number of gallons it treats, but somewhere in my files I have an email direct from StarTron confirming their formulations.

 

[JoshKeller]

also, in my motor, if i wasnt using champion ql82c plugs, it was rough to start

 

[restornator]

Here's mine. Love this motor. Drove 8 hours in a rented Chevy Aveo to pick it up. The powerpack is the weak link (quick start and S.L.O.W. features), and quite costly to replace. I lucked out and got one on ebay for $50.

https://www.youtube.com/watch?v=RDTD8tX-SJs