1969 Merc 40 4HP

[cloudman]

Hello all, I just took off the sparkplug to check it, and it looks like the tread on the part that the plug screws into is breaking off, and it is making it hard to put the plug back in, that part of the powerhead that the plug screws into comes off, but I have no idea what it is call, I figure I may be able to get a different one but I have no idea where to find it, does anyone know what it is called, and also where may I find one, that would fit my engine. Thankyou

 

[thefairlaneman]

Re: 1969 Merc 40 4HP

You will need to install a 'heli coil" into the head. You can get them with instructions at Harbor freight. Be careful not to let metal shavings fall into the cylinder . Use an air blow gun to blow it out before you install the plug.

 

[JB]

Re: 1969 Merc 40 4HP

I have seen a bunch of threads lately where helicoils have come out of heads.

I always favored TimeSerts over helicoils because they are aluminum alloy and conduct heat the way the head is supposed to. The steel helicoil does not.

Now I have a second reason to use TimeSerts. They stay in place.

 

[John in WI]

Re: 1969 Merc 40 4HP

If you use a Heli-Coil, lube up the tap with some heavy grease.
It helps hold the metal chips and keeps them from falling in the cylinder.