Vintage Mercury Cooling Issue

[tpenfield]

I pulled the spark plugs, cleaned them up checked the wiring, etc.

The engine WAS running on 1 cylinder, by the looks of the plugs, the bottom one was firing, not the top cylinder.

Runs good now - at least for the time being

I think I’ll get some new plugs for it.

 

[tpenfield]

I installed some new spark plugs and took the boat out for a test ride. After 30 seconds of joy, the engine resumed running on one cylinder.

I brought the engine home, pulled the flywheel and checked the coils for continuity (about 1 ohm each) and then I set the points, which were a little worn and were not pulling the full gap (0.020")

Still no joy, so I think I'll be checking the wiring, etc. . . . maybe get a spark tester.

 

[tpenfield]

Thinking to myself . . .

Oh yea, I have a timing light, that will show if there is spark . . . or not.

 

[tpenfield]

Quick Update . . .

The timing light confirmed the bottom cylinder not firing. I pulled the plug and it looked like it got some carbon fouling right away. . . (really not the right type of spark plug).

I cleaned it up and now both cylinders are firing. Probably going to see about getting the right type of plug.

 

[tpenfield]

Ignition System Update . . .

I went through the ignition system the past few days. Coil resistance is about 1 ohm each . . . maybe a bit less.

The cam levers on the points were a bit worn and getting only about 0.010 gap. So, I set those to the 0.020 spec. I also cleaned up the the connections.
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For now, the engine is running on both cylinders.

I also found that the cooling water flow was not getting to the top cylinder. It seemed like an air pocket or something. Anyway, I replaced the plug on the top of the powerhead with a right angle barb fitting and ran a second 'pee' line. A bit unusual, but it worked.

I think I should probably get a newer version of this motor, so it has the better ignition system.

 

[tpenfield]

New spark plugs finally arrived. I'll be putting them in this week and see how things go.

If I can make it thru the season on this motor, then it may be a keeper. Meanwhile, I am looking on FB and CL for back-ups.