2nd Cylinder Issue - 72 JOHNSON 125HP

[LOSTBOATER72]

ASSISTANCE IS GREATLY APPRECIATED-<br /><br />I have a low hour 125 HP Johnson listed above and the second cylinder piston was hitting the electrode into the plug as I was using the incorrect plug. Now this cylinder is getting spark but not working properly. Any suggestions would be greatly appreciated. Could it be due to a short under the flywheel somewhere due to the plug electrode touching the center of the plug? I do not want to have to shell out $$$$ as I have already put over $2k into my 72 Glastron and Johnson combo. Thanks Much..<br /><br />Hoping to be on the lake Soon!!!!<br />LostBoater72

 

[Joe Reeves]

Re: 2nd Cylinder Issue - 72 JOHNSON 125HP

Lost..... If you had the same plugs in all four cylinders, and one was being hit by a piston, it is not the fault of the plug. You didn't say what plug(s) you were using.<br /><br />The cause would be that something in that particular cylinder is breaking up and hitting the plug electrode. Remove the cylinder head to inspect the piston etc.

 

[RVAHA]

Re: 2nd Cylinder Issue - 72 JOHNSON 125HP

I had this same problem just yesterday with my 1979 Johnson 175. I pulled the starboard head and found the piston and head destroyed. Specifically, the piston and head had many pock marks and the piston had a lot of play, which allowed it to bang into the plug. <br /><br />I was able to poke a screwdriver thru the spark plug hole and see a lot of piston play. This convinced me to remove the head, and see the bad news.<br /><br />Hopefully yours isn't as bad! Good luck,'<br /><br />Rick

 

[LOSTBOATER72]

Re: 2nd Cylinder Issue - 72 JOHNSON 125HP

The cylinder I am speaking of ran great for about 4-5 trips out after 8 years of outboard graveyard. It was garaged the entire time, i rebuilt the carbs, replaced the entire fuel line and emptied the gas tank and cleaned it out. The motor ran great and then it started hitting the plug in cylinder 2 with Splitfire SF163D if i remember correctly. I went and got NGK's but they hit as well. I recently bought Autolights without surface spark and they work ok but the second cylinder is just plain not giving any power. Also I just bought Champion L77JC4's and they work well but the same cylinder is just plain not working. Their is no play in the piston, it has less than 200 hours on the engine. It ran perfect but now I am lost. Should I break down and take to a shop? Please help!!!<br /><br />Mr. Lost boater - will be awhile before the lake!!!

 

[RVAHA]

Re: 2nd Cylinder Issue - 72 JOHNSON 125HP

Something is wrong with the piston. Pulling the head should give you an answer before you take it in.

 

[ledgefinder]

Re: 2nd Cylinder Issue - 72 JOHNSON 125HP

Be advised that pulling the head is no big deal on those. Gasket is readily available from many sources (including iBoats) for about $11. Get a manual, or come back here for torquing instructions. <br /><br />BTW, there is a water jacket bolted to the head. No need to remove that, it is bolted atop the head & can come right off with the head.

 

[ledgefinder]

Re: 2nd Cylinder Issue - 72 JOHNSON 125HP

If you've lost the powerhead, keep in mind that any 1969-72 85-125hp OMC V4 is a bolt-on replacement. Good used powerheads are available fairly easily, since the hydroelectric shift lower units and powerpacks are BIG $ from the dealers. They're all nearly the same displacement (94-100 cubic inches), so the power difference isn't as great as you might otherwise think.