Johnson 15HP 1997...continuing problems

[Joe Reeves]

You asked: "Any advice on what to use to patch a small ding on the machined crankcase surface where it mates with the head?"

At any reliable marine type store..... purchase GRAY "Marine-Tex", an epoxy that drys overnight to be harder than the steel or aluminum it's being used to repair. It also comes in the color of WHITE... but DO NOT use the WHITE epoxy... use the "Gray" substance. After it drys, you can sand, file, drill, tap it, whatever. Just be absolutely sure that the area you're repairing is absolutely clean!

 

[bigfish55]

Thanks Joe. I really thought the JB weld was going to do the job. After it hardened for a day, I had to file it flush with the surface using a couple of very fine tooth files. It did seem as "hard" as steel, but something reacted with it, turning it into not much more than mush.

 

[bigfish55]

I was reading the data sheet on Marine Tex and it really doesn't mention temperatures. Will it handle the normal operating temp for this application?

 

[oldboat1]

Wasn't aware that there was a difference between the white and grey (good to know), but the stuff has been used for years to patch just about anything, including engine blocks.

 

[thatone123]

As an aside I have used and repaired many of these 15's. The enchilada Mexican carb which I think is on yours is very problem prone in my experience so much so that I went back to ol' reliable, the pre-90's models. I am up North where many fear to tread and need ultra reliability.

 

[Joe Reeves]

I was reading the data sheet on Marine Tex and it really doesn't mention temperatures. Will it handle the normal operating temp for this application?

On the coldest Winter day of So Jersey, then later in life, the hottest Summer day in Tampa... the gray Marine-Tex has never let me down. On top of Mt Everest, one might have a problem!

Back in the 1980's, I patched a baseball size hole in the forward portion of a looper 225 crankcase with that gray stuff just to see how it would hold up.... still running!

 

[bigfish55]

I used the Marine Tex and it seems like a good product...only time will tell. Anyway, I did all I could in the barrel so I took it out on the lake all day Sat and Sun. Motor worked fine, sometimes it took 3 pulls to start and sometimes only one. The throttle is a little tempermental at certain RPMs, but all in all it is totally fishable and seemingly reliable now. I thought it could be the plugs from running 25:1 but they looked pretty good. Weather permitting I'll be out again this weekend and it will be time to try WOT.

I really want to thank everyone on here who has helped me with this project. I HOPE that's it for this motor. Now I'm going to try and troubleshoot my 1968 9.5 Evinrude. It seems like a more complicated motor than the 97 Johnson.

 

[Crosbyman]

9.5's are ok … all the ones (5-6) I purchased at <$60 all worked out ok after basic maintenance (carb coil impeller plugs etc..) ...even the seized ones came out ok

expect low compression numbers (65-75) but they run ok

http://www.leeroysramblings.com/OMC_9.5.htm

 

[bigfish55]

I was truly hoping that I wouldn't have to come back here. My motor has run great for 5 full day fishing trips, but yesterday when I tried to start it after running great all day...nothing. Like no fuel. Took it to my shop for a few checks...good spark, 95 compression on both cylinders. drained carb, and the fuel pump is filling it up just fine. That's as far as I got last night..got up too early and was tired. It's like it is getting ZERO fuel...not even a cough or sputter. The only other problem I had was last weekend it was making a metallic "noise" and runnin rough at full throttle. Pulled the flywheel, and one of the screws that holds the "charge coil" had worked its way loose and was rubbing against the underside of the flywheel. Which is strange since I never messed with any of the ignition components, except to remove the plates. Ran fine and noise gone after tightening. I am getting very frustrated with this motor in terms of dependability. Next step? Pull newly rebuilt card and re-clean?

 

[Joe Reeves]

The charge coil screw coming loose brings up some concern. That could have let the coil drift to be in contact with the flywheel magnets... check it if you already haven't.

Note that there is bevel on top of the aluminum seats where the coils etc sit... the coils must align with the top inside edge of that bevel (unless one has the special alignment tool) in order to be properly spaced from the flywheel magnets.

The explanation of "good spark" doesn't quite do it.... The spark, with s/plugs removed, must jump a air gap of 7/16" with a strong blue lightning like flame... a real SNAP! Does it? Note that the 7/16" air gap is important. Testers are available at any auto parts store... or you can build the following:
********************
(Spark Tester - Home Made)
(J. Reeves)

You can use a medium size philips screwdriver (#2 I believe) inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark or build the following:

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:

..........X1..........X2

.................X..(grd)

..........X3..........X4

This can obviously be modified to a 6 or 8 cylinder setup tester.
********************
Of course, something could have found its way into the carburetor... a quick test would be to spray some fuel mixture into the carburetor throat or into the cylinders themselves. If the engine runs on that sprayed fuel but not via the carburetor in itself.... well, that pretty much spells "carb problem".

Let us know what you find.

 

[thatone123]

Yes, unless it is cold out, pressure will build up quick even at that temp and the hotter it is the more pressure ensues.

 

[bigfish55]

I put the motor back in the barrel today up and filled it up before I realized I forgot to check the spark gap. The light wasn't good where it was but I decided to try and check it anyway. I used a proper size dill bit in the boot so it was just snug. A 1/4" inch bit was too small. I wrapped a rag around it and gave it a pull. I got a nice jolt, but also noticed that it had a sign of life. Put the plug wire back on and it started right up...idled nicely and revved smoothly. I also removed the charge coil and re-installed, but I think it was OK as it was.

I have been using a pretty old 34# thrust trolling motor when this one has been down (weather permitting) and it dawned on me that this mid 90s Motrorguide had a LOT of hours on it. I primarily fish Lake Mohave AZ and it can get really windy fast, so today I bought a 55# Minnkota. Kind of eerie in a way. I still don't know why it wouldn't start, and still don't trust it, but for now there's not much I can do but use it. Thanks for the advice as always!