1978 Mercury 70HP Spark Plug wires.

Any idea how to remove? These screw in? I started pulling lightly and they didnt give so I stopped. Service manual says to remove to test coil, but doesn't tell me how to remove. I see on parts schematic that you can order just the wire so I know they aren't built into the coil. Any help please? Thank you

Re: 1978 Mercury 70HP Spark Plug wires.

I think that they screw in. You should be able to test the coil with them still in and see if the coil is the problem. Then try to remove the wire.
Oldman570

Re: 1978 Mercury 70HP Spark Plug wires.

oldman570 said:

I think that they screw in. You should be able to test the coil with them still in and see if the coil is the problem. Then try to remove the wire.
Oldman570

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Gotcha. As per my other thread you replied to, I'm about 99.8% sure its the coil, but could be the wire. I have a complete assembly on its way, but I'd like to figure out exactly whats bad. I couldn't get a lead into the boot very reliably so I wanted to just take it off. I'll try twisting it a bit tonight. Thanks for the input.

Re: 1978 Mercury 70HP Spark Plug wires.

My '77 Merc 500 Thunderbolt wires just push in, I just replaced the wires last year. When you push them in, they will click. The end of the wire has a metal piece crimped on that has a finger that clicks in. They should just carfefully yank out.

Testing the coil is easy and you dont need to pull the wires from the coil, measure from the plug cap. If I remember correctly, mine read about 1150 ohms. Remember, if you have a bad plug wire, your coil will self destruct, it will burn right thru the coil to ground, that energy needs to go somewhere.

Compare all coils against each other, if you have a bad one you'll know it. Stators are known to cause this too.