78 ? Johnson 25 hp coil replacement

[Navarre]

I have a possible 1978 Johnson 25 hp motor. Model No# (25R78) . I've been told that it was a 77 model. What I'm doing is replacing the two coils but want to make sure I'm getting the right ones for the right motor. The ones I looked at through iboats were totally different from the ones that are on my motor right now.
Here are the ones I looked at:

CDI coil 183-2366
SIERRA 18-5176
MALLORY 9-23103

I could not find any numbers on the old ones that are on my motor right now, so I will try and post a pic of them.
Any help ? Don't want to buy the wrong ones on the first go around.

 

[outlawfox13]

Re: 78 ? Johnson 25 hp coil replacement

If your Model # is 25R78C than you are looking at the correct parts. You also have a coil under the flywheel which will mostlikely need replaced as well. Go to http://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1978&hp=25 and input model #, look up magneto group and match the picture with the part #'s below. Good luck with the rebuild.

 

[AlTn]

Re: 78 ? Johnson 25 hp coil replacement

if it has a powerpack it's a 1977 and above..if not it's a 1976 or later...is there a powerpack on the opposite side of the engine in your pic? < looking at the amphenol plugs going across the head I'd guess there is >

 

[Navarre]

Re: 78 ? Johnson 25 hp coil replacement

if it has a powerpack it's a 1977 and above..if not it's a 1976 or later...is there a powerpack on the opposite side of the engine in your pic? < looking at the amphenol plugs going across the head I'd guess there is >

Thanks outlaw for the info.

And yes there is a power pack on the otherside of the motor. I replaced that a few months ago hoping that would fix the problem of my motor bogging after about ten minutes of running at WOT but it didn't, it ran once without bogging after I replaced the power pack but only maybe because it was cold outside and didnt reach the fail temp as it did the other day when it was warm.
I read up on other post suggesting that it could possibly be the coils heating up and failing, so that is my next attempt to replace those since it will be an easy fix before I get into other parts of the motor.

 

[AlTn]

Re: 78 ? Johnson 25 hp coil replacement

is it losing spark when it gets hot?....that's the starting point

 

[Navarre]

Re: 78 ? Johnson 25 hp coil replacement

I dont belive it is losing spark, it bogs down like theres a rope wrapped around the prop then dies. After it dies I will try and crank it (pull start) and it will run for about three seconds and die again after that I have to wait untill it completly cools down before it will run again.
I had a rebuild about 5 years ago on the pistons. The motor had locked up from getting to hot . But it ran fine untill a few months ago.

 

[AlTn]

Re: 78 ? Johnson 25 hp coil replacement

check the temp of the engine next time as it may be overheating and seizing again...check for spark as well at the same time..how long has it been since the impeller was replaced?

 

[outlawfox13]

Re: 78 ? Johnson 25 hp coil replacement

+1, and when it bogged down did you check the primer bulb was it firm?

 

[Navarre]

Re: 78 ? Johnson 25 hp coil replacement

check the temp of the engine next time as it may be overheating and seizing again...check for spark as well at the same time..how long has it been since the impeller was replaced?

Sorry just got back from a twelve hour day work week.

The motor doesnt, seem to be getting that hot ,the pee hole water isnt extremely hot to the touch. The motor still turns over with ease after it dies out and tries to crank for about three seconds.
I replaced the impeller about year ago thinking it was overheating due to water pump going bad but to no avail. Also the primer bulb on the fuel tank stays firm, I even tried pumping the bulb as it was bogging down to see if it would pick back up but that didnt work either.
Here is a list of things I have done to it so far.

New water pump and seals
New Prop
Removed carb, cleaned and replaced gasket
New Spark Plugs, gapped at 030
New power pack
New fuel line and bulb from tank
Had motor rebuilt about 5 or 6 years ago (locked up)

Its just got me frustrated to the point of selling the motor LOL, even though I'm sure it's a easy fix.

 

[hidef]

Re: 78 ? Johnson 25 hp coil replacement

Have you changed out the thermostat? The pee stream from the water pump indicator doesn't flow through the block. Your engine could be over heating if the thermostat is stuck closed.

See item # 19 #19 — 378065 — THERMOSTAT

http://www.marineengine.com/parts/j...cturer=Johnson&section=Cylinder+And+Crankcase

 

[AlTn]

Re: 78 ? Johnson 25 hp coil replacement

possibly the vent on the tank isn't open < try just opening the gas cap and running with it off for a short while>...fuel pump could be failing, although pumping the primer bulb should fill the carb bowl.
I've found it helpful to run a clear fuel line from the fuel pump to the carb to help diagnose fuel delivery problems.
When it quits, how long can you hold a couple of fingers on the area of the block just behind the head?

 

[Navarre]

Re: 78 ? Johnson 25 hp coil replacement

Have you changed out the thermostat? The pee stream from the water pump indicator doesn't flow through the block. Your engine could be over heating if the thermostat is stuck closed.

See item # 19 #19 — 378065 — THERMOSTAT

http://www.marineengine.com/parts/j...nufacturer=Johnson?ion=Cylinder+And+Crankcase

Have not replaced the thermo yet, didnt think of that one.
Thanks

AITn . I havent tested the block with my finger just yet either. My first thought was it was getting to hot because the motor would act like it was binding or seizing up but not totaly locking up, just a bogging down sound (i.e. rope around prop feeling)
I also have two fuel tanks on board and tried them both and the same result would happen, but I haven't tried taking the fuel cap off completely.
I did take the fuel pump off and checked it for pin holes and clogged screen but it looked fine. I even pumped the bulb and had fuel pumping through the fule line with no problem.

 

[Navarre]

Re: 78 ? Johnson 25 hp coil replacement

Ok ran the motor in a tank till it died on me. As it was running I checked the pee hole and the water was hot but not scalding. No spark after it died. Couldnt even get it to fire off with carb starter fluid.( I know, I know not good but we have all done it at least once So that leads me to belive that it is electrical. I took off fuel lines and replaced them with new ones before running it in the tank. After it died i felt the block with my finger and the side where the power pack is was extremely hot held my finger there for less than a second. The area where the spark plugs are and thermostat was fairly warm, held my finger there for three to four seconds. Bottom side of magneto was hot about two second finger hold.

So now off to save money and buy parts

Thanks

 

[Navarre]

Re: 78 ? Johnson 25 hp coil replacement... GOT ER RUNNING

Re: 78 ? Johnson 25 hp coil replacement... GOT ER RUNNING

OK it's September and Febuary was my last post. (Finally saved the money for parts).
I can now say that I am a proud owner of a 1978 Johnson 25 hp motor that is back up and running.. Thanks to this forum and all its knowledge. And my determination to fix it !

Run Down in order of what I did to her.

1. Replaced power pack (was the first attempt, still died)
2. Replaced water pump impeller (thinking it was over heating)
3. Took carberator off cleaned it ( did not use a kit)
4. Saved money and got on "iboats forum" day in and day out checking out all threads as to why it would die on me after running WOT .
5. Ordered parts... (A),Sensor assy. #0583387 (B), Coil and Lamination assy # 0582059 (C), Fuel pump kit #393103 (D), Carb kit #0396701
6. Pulled fly wheel and put it all together, again using "iboats forum"
7. Dropped her in a trash can full of water, third pull fired right up... YES!!
8. Put her in the water for a good test run.. took a few more pulls than three this time . was getting blisters from the rope pullin, finally she fired up.
9. Crusied around put her back into WOT ran great. I was GRINNIN !! All of a sudden SHE DIED ???? I was thinking WT #%%@$
10. My buddy could see I was getting ready to throw it in the bay, so he said let me look at it....... Now i'm no mechanic but he got back there and SAID.. Oh your throttle arm (small metal arm that adjust your throttle as you give it gas) has fallen off your carb thats probably been your problem the whole time... "I'm like, YOU HAVE GOT TO BE FRIGGIN KIDDIN ME".
Well needless to say if that was the problem or not at least I have pretty much rebuilt the motor so she should be good to go for my Grandkids to enjoy on down the road.

By the way I never did replace the coils as my original post question was about. LOL

 

[jasper60103]

Re: 78 ? Johnson 25 hp coil replacement... GOT ER RUNNING

Re: 78 ? Johnson 25 hp coil replacement... GOT ER RUNNING

Congrats on getting her going.
No doubt you've learned a lot and can
feel confident the motor is reliable now.

Thanks for the update and nice pics.
jasper

 

[AlTn]

Re: 78 ? Johnson 25 hp coil replacement... GOT ER RUNNING

Re: 78 ? Johnson 25 hp coil replacement... GOT ER RUNNING

with Jasper on the thumbs up....look at all the experience and knowledge you've gained!

 

[Navarre]

Re: 78 ? Johnson 25 hp coil replacement... GOT ER RUNNING

Re: 78 ? Johnson 25 hp coil replacement... GOT ER RUNNING

I agree, I have definitely gained the experience.
Especially in a 1978 25hp Johnson outboard. So much so that I was even able to break down the carb. on my genarator and get it running just before the storm Isaac came by.

Thanks again to iboats and all the people that helped me out on here.
Feel free to use the pics I have posted on here for reference if yall want too.