Head bolt

MDeVito

Petty Officer 3rd Class
Joined
Mar 18, 2004
Messages
78
I have a 1995 88 special evinrude. I recently installed a thermostat and the head bolt that I used will not torque as tight as it should be. Should I remove the head bolts, retap them, and use new bolts?
 

ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: Head bolt

It may not be as easy as that if the threads are stripped.Since the block is aluminum and the bolts are steel,I'm almost certain the the bolt holes will need to be heli-coiled,oversized,or backfill welded and remachined.Good luck.
 

jim dozier

Lieutenant Commander
Joined
Jan 8, 2003
Messages
1,970
Re: Head bolt

Your threads are probably stripped. Install a helicoil. They come in a kit available at NAPA auto parts stores. Get comfortable with them you will need them again sometime. See you in St. Pete.
 

ob

Admiral
Joined
Aug 16, 2002
Messages
6,992
Re: Head bolt

I thought you did a quite nice job at explaining a helicoil Middleground. :)
 

R.Johnson

Rear Admiral
Joined
Sep 24, 2003
Messages
4,446
Re: Head bolt

phatmanmike: marine-tex is nothing but a glue, you can't make threads out of this and torgue to spec's.
 

jim dozier

Lieutenant Commander
Joined
Jan 8, 2003
Messages
1,970
Re: Head bolt

The helicoil as middleground explained so nicely simply requires that you drill out the old threads with a specified drill size and retap the new hole with a tap supplied with the kit. The helicoil is inserted (screwed) into the now larger tapped hole and the internal diameter of the helicoil spring (stainless steel) fits the original bolt diameter. Now you have new stainless steel threads with a stainless steel bolt. Its better than OEM.
 

MDeVito

Petty Officer 3rd Class
Joined
Mar 18, 2004
Messages
78
Re: Head bolt

What if some bits of what you drill out go inside the head? How would you extract? Or would you just take the whole head off for this procedure?
 

MDeVito

Petty Officer 3rd Class
Joined
Mar 18, 2004
Messages
78
Re: Head bolt

Would my best bet be to take the whole head off?
 

steviecops

Chief Petty Officer
Joined
Oct 3, 2003
Messages
585
Re: Head bolt

I'm no expert, but I would!<br /><br />Having said that, it's not like your driling out a spark plug hole, so you probably wouldn't get any swarf inside the cylinders.<br /><br />Good luck<br />Steve
 

OBJ

Supreme Mariner
Joined
Dec 27, 2002
Messages
10,161
Re: Head bolt

Steve is right. None of the head bolts should go through to the cylinders. If you want to play safe, coat the tap with some heavy grease. This will catch the "swarf" (that's a term I ain't heard before) as you work the tap.
 
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