1997 Merc 75HP

Anything special needed to pull the plugs on these motors? I'm going to have one of my sons do a compression check on one and want to be sure he has the right tools. Can you pull them with a crescent wrench? Or need 13/16 socket?

Re: 1997 Merc 75HP

Whoops, thats a 1994 not a 97.

Re: 1997 Merc 75HP

I'd get the correct tool, if for any reason to teach you son how to do it correctly with the proper tool. But the cresent wrench would work if you can get on the plug.

Re: 1997 Merc 75HP

Word to the wise. The head where the plug screws in is aluminum. Very easy to strip. When I was younger I thought things had to be really tight.....knew nothing of torque specs.

I stripped the threads on numerous fastners including a lawnmower and OB motor.

So, when he reinstalls the plugs, pull them down till the wrench stops turning with light pressure and then give the end of the wrench a moderate tap with your hand and leave it at that.

If you are installing new plugs, the seal will have to be compressed so you will experience mild resistance as it is compressing, but when it is fully compressed the resistance goes up sharply. Stop there and give here the last tap.

Mark