1959 Mercury Mark 58A no spark

[jparks89]

I just got a 1959 mercury mark 58A 40hp and i'm not getting any spark on all 4 plugs. Any suggestions on what to look for or test? I'm new to outboard motors so you might have to explain. Any help is appreciated.

 

[racerone]

The magneto is turning I assume.--------About halfway on the magneto assemly you will find some screws.----You can split the distributor / magneto and remove it for inspection.-------Most likely the points need to be cleaned and set at 0.010".---------And there is no need to worry about the timing by removing the bottom half of the mageto as it can only go on one way.

 

[racerone]

Test for spark before re-installing the magneto.

 

[jparks89]

There's a lot of open wires going to the distributor that are corroded. I'm going to try and replace all the corroded wires and see if that helps. I put jumper cables on the starter and block and the electric start engages and turns but there's still no spark.

 

[racerone]

Post # 2 has key information for you.

 

[jparks89]

I also noticed that the mercury is all gone out of the mercury switch any recommendations for a replacement? I know they have ball switches now. or could I just bypass it?

 

[jparks89]

Test for spark before re-installing the magneto.

So i took the distributor/magneto off and cleaned the points and set it to 0.010". When you're testing for spark, all I have is a digital meter, what setting do you put it on? I tested the positive and negative coming off the coil and was getting like 1.5 does that mean it's a bad coil?

 

[Chinewalker]

I also noticed that the mercury is all gone out of the mercury switch any recommendations for a replacement? I know they have ball switches now. or could I just bypass it?

The mercury switch is only there to prevent starting with the motor tilted up. Apparently was a big problem back in the day?

 

[Chinewalker]

So i took the distributor/magneto off and cleaned the points and set it to 0.010". When you're testing for spark, all I have is a digital meter, what setting do you put it on? I tested the positive and negative coming off the coil and was getting like 1.5 does that mean it's a bad coil?

Shouldn't need any sort of meter to test for spark. With the cap OFF, hold the coil tang about 3/4-inch away from a bench vice (or other large metal object) and the mag body against said vice. Spin the mag CLOCKWISE and note if you have spark. If no, then move on to checking for other issues. Generally, if those old coils appear to be in good shape, .ie no cracks or arcing tracks, they're likely good. Most mags I've had issues with were either with dirty or worn points or bad condensers.

 

[jparks89]

Shouldn't need any sort of meter to test for spark. With the cap OFF, hold the coil tang about 3/4-inch away from a bench vice (or other large metal object) and the mag body against said vice. Spin the mag CLOCKWISE and note if you have spark. If no, then move on to checking for other issues. Generally, if those old coils appear to be in good shape, .ie no cracks or arcing tracks, they're likely good. Most mags I've had issues with were either with dirty or worn points or bad condensers.

So when I spin the shaft I get spark between the points but when I put everything back together and hook up spark plugs I don't get anything with them. Is it possible something is going on with the distributor?

 

[racerone]

???---Spark between the points ?-No spark from the coil ?-----Could be a bad condenser.--------You are not using 12 volts anywhere I hope.

 

[jparks89]

On this engine the points, magneto, coil, and condenser aren't below the flywheel. There's a belt that goes from the flywheel to a separate shaft and that's what spins the shaft for the magneto and points. So there is spark between the points there.

 

[GA_Boater]

When you had the magneto apart, what was the condition of the cap and rotor? And the carbon button in the cap?

Finally, remove the wire, white I think, on the side stud of the magneto. Try cranking and see if the plugs spark.

 

[racerone]

Sorry, but I am well aware of what your distributor and motor look like.----I own half a dozen of those 4 cylinder motors too.----Do you have spark coming from the coil ???????

 

[jparks89]

So the cap and rotor looked fine. I am getting spark from the coil. I need to check the condition of the wires going to the plug they might need to be snipped.

 

[merc850]

Just use an ohmmeter to check the continuity between each wire and the post in the cap it should be close to zero, those are solid core wires not carbon and they are held in the cap by little screws.

 

[jparks89]

Just use an ohmmeter to check the continuity between each wire and the post in the cap it should be close to zero, those are solid core wires not carbon and they are held in the cap by little screws.

I took the wires out of the cap yesterday and there are no wires sticking out of the rubber. So do i just need to snip it back a little bit and make sure there's wire sticking out?

 

[jparks89]

i've never replaced spark plug wires so i'm not really sure how to do it.

 

[merc850]

Just cut the rubber back enough to see the end of the wire and turn the screws all the way in to make contact, you should also check the boot end. Did you check the wire (s) for continuity? When you put the rotor on use a little smear of gasket maker to hold it onto the shaft. If this is really a big problem post some pictures of the components.

 

[jparks89]

Ok, I did take a multimeter to it and it was just about zero. I'll try exposing wires and see if the spark will go to the plugs. If I snip the rubber back I might not have enough length to go from the distributor to the plugs in the cylinders, but I just want to see if i'll get spark. Will new carbon plug wires work?