Thermostat cover, Helicoil or insert?

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01-17-2022, 06:59 PM
Cpartipilo

Thermostat cover, Helicoil or insert?

Hello guys,

2006 Mercury 115hp optimax - Serial 1B255833

I was pulling the thermostat/poppet cover and a bolt snapped flush with the block. Punched, drilled it close to center and in my last pass with the 1/4 bit before switching to the thread tap I wobbled the drill and the bit snapped. :crying:
After lots of swearing, frustration and more work I got the bit out but now I am left with a hole bigger than the original.

I searched and read that in many areas helicoils are not recommended, but this being a part with no strength other than holding the cover flush would a helicoil do, or should I just bite the bullet and get an SS insert in there?

I already have the helicoil kit, the other stuff I would have to buy.
01-18-2022, 07:32 AM
JOE54

should work fine there , i hate salt water mtrs :mad: , good luck
01-18-2022, 02:04 PM
Cpartipilo

Thank you as always Joe.

I had a hard time because the hole was a bit mangled but i got 2 helicoils stacked and was able to thread the original bolt back in there at the right torque.
Used some aviation gasket sealer on the gasket and some tefgel on the bolts to avoid having to deal with this crap again. (at least on the thermostat cover) :thumb up2:
02-03-2022, 07:28 PM
DaveR

Tefgel is good stuff.
02-05-2022, 05:30 PM
Proline25

Had that same problem with a motor that I bought. The original owner had mangled the bolt hole and did not install the thermostat on that bank. I cleaned out the bolt holes and installed 4 studs rather than using bolts. Now all that has to be done to remove the thermostats is remove the 4 nuts and slid the housing off the head.
02-06-2022, 04:41 PM
EuropeanAM

Quote:

Originally Posted by Proline25

Had that same problem with a motor that I bought. The original owner had mangled the bolt hole and did not install the thermostat on that bank. I cleaned out the bolt holes and installed 4 studs rather than using bolts. Now all that has to be done to remove the thermostats is remove the 4 nuts and slid the housing off the head.

Cool idea- would work well on EFI models... many of the Opti's would be almost impossible to get the cover off the studs without removing other components.