heli coils

[crab bait]

striped my ob gear oil top drain screw..<br /><br />it's a 5mm dia bolt.. in a recessed area..<br /><br />should i get a 5mm helicoil..?? or smaller ..?? <br /><br />reason for asking is,, all i need is plugged hole.. 1/8" would be find.. it's just to 'see'/run out of fill level.. doesn't need to be 5mm.. an do'nt even want to take away from the recessed area's dimention.. as per good screw head/washer seal..<br /><br />what size heli coil do i need .. <br /><br />also any 411/help is appreciated..

 

[tommays]

Re: heli coils

The 5 MM coil will be about the OD of a 6 MM bolt<br /><br />Your probley cant go smaller because the hole is allready to big for an M4 coil <br /><br />The screw is that small ? i am use to merc with the 3/8 thread<br /><br />tommays

 

[Laddies]

Re: heli coils

I have heli-coiled mercrusier drains many times just get the threads clean and dry, I use loctite 271 to keep the coils in place

 

[crab bait]

Re: heli coils

thanks fellas,, it's measures 5 mm but now know ( via hardware store ) that it a M8-125 pitch/thread.. <br /><br />again,, what size/kind heli coil should i get.. <br /><br />an what to do about/stop the 'tap shavin's ' in the lower unit ..??

 

[RPJS]

Re: heli coils

An M8 x 1.25 x1.5D coil will fit (a striped M8 thread is very nearly the correct tapping size for the heli coil)<br />When fitting the coil be very careful with the snap off drive tang, you dont want to drop it into the gear box.

 

[tommays]

Re: heli coils

Well step one is Usally going to require drilling to bring it to size <br /><br />A shop vac and grease on the drill will get most of it<br /><br />If you drain the case and hook up some air to the fill fitting that should blast 99% of it out as you make it<br /><br />The real BIG DEAL is starting straight and staying that way <br /><br /><br />I guess the only good news is its ALU and not steel<br /><br />Same thing when your taping it like RPJS said the tang would be the real KILLER if it gets lost it would do some real dammage<br /><br /><br />tommays

 

[crab bait]

Re: heli coils

thanks all again..<br /><br />i'm gonna go to plan 'B'..<br /><br />i have about 3/4 " inch worth of tapped motor metal/female thread.. the screw was only 3/8 " long.. <br /><br />i still have half ammount of used thread good to go.. <br /><br />ordered M8-125 nylon bolt from a supplier ..havta by a 100 minimum an wait 10 days to come in from europe.. <br /><br />i'm sure this'll work.. ( i hope )

 

[rodbolt]

Re: heli coils

if this is a yam or a nissan you will find the standard helicoil is usually to long. usually I have to cut off about 3 coils.<br /> and the drive tang can be removed with a slim pair of needle nose.<br /> then I reuse the original fill/drain plug and gasket.