Coil Adapter / Installation

[Cordovakid]

I purchased an aftermarket coil for my 25hp Merc. Thecoil came with a soft plastic covering sleeve that fits over the back of the coil (opposite to the wire). My motor's coil setup has a ground plate on the negative terminal with a screw bolt going down through the terminal to mount the coil to the engine ground. This new coil had a smaller ground "strap", which I changed out for my original ground plate with the bolt hole in it. My question is, can I install / operate this coil without the soft plastic covering on the coil - without the cover, it has the exposed shiny off-white plastic hard coating on the top side, and I want to make sure I don't damage the inside of the coil with the pressure of the bolt, or exposing it to the heat of the engine.

 

[flyingscott]

What year is your motor? those coils usually have the rubber boot on them.

 

[Cordovakid]

1980 Mercury 25hp, manual start. I am speaking about the actual plastic housing of the coil...the original coil is black hard plastic. The aftermarket has an off-white shiny plastic composite material on the top side and is harder black plastic on the bottom. The supplier provided a soft plastic sleeve to cover the whole wire end and top/bottom of the coil, but I need to run a bolt through the top / bottom to secure the grounding strap and coil to the block.

 

[flyingscott]

Did you get the spacer with the coil that goes through the bolt hole. If you did just bolt it on and go, if you didn't get the spacer you should be able to pull it out of the old coil and use that.

 

[Cordovakid]

Yes, I received the spacer that goes through the bolt hole. I removed the (removable) soft cover for the coil, connected the ground plate from my old coil to the negative, connected the positive from the switch box, and routed the bolt through the top of the coil and the through the spacer, and then screwed it to the motor housing. It is secure, and seems to fit correctly...I'm just asking whether it makes a difference if I don't use the soft plastic coil cover which was provided. Otherwise, I would have to cut something out from the provided cover to use it for the bolt to go through and still allow the coil to mount flush to the motor housing. Thoughts?

 

[flyingscott]

No you do not need it. Just use whatever was there before.

 

[Cordovakid]

OK thanks the help...just to clarify one thing - the old OEM coil had a hard plastic outside all around, and this coil has the hard plastic on the bottom and sides, but an "open" side of a shiny white material, which is slightly recessed on the top. I just don't want to crack the ferrite core if the top side is softer....thx for the advice.

 

[flyingscott]

The rubber boot is for a later mounting set-up as is your coil. What brand coil do you have you may want to call them. You can only mount the coil one way and the spacer should keep it from being crushed or damaged.

 

[Cordovakid]

It's a Sierra coil, Sierra part #18-5186...I agree the coil can only be mounted one way, I'm just curious as to what the white plastic material is on the top of the coil. I'm using the spacer, as well as the bolt spacer which goes into the center of the coil. Fits just fine, it's just a really weird top part to this coil with the one white side...just looks like the inside protective material for the coil.