Thanks KosmicKuda,it’s 9/16” so 3/8 so this kit for $30 would be the one. When you say use sealant,are you meaning I should put red loctite on the helicoil when it’s inserted? In one of the videos online they said helicoil recommends never stacking helicoils and never putting loctite on them. What would you recommend? Also in the videos I watched it shows the tang being broken off the helicoil after it’s driven on. I wouldn’t want that to fall into the engine.
Red Loctite is generally referred to as non-removable. (Without heat)
Blue Loctite is easily removable.
It can double as a sealer
Thanks KosmicKuda,it’s 9/16” so 3/8 so this kit for $30 would be the one. When you say use sealant,are you meaning I should put red loctite on the helicoil when it’s inserted? In one of the videos online they said helicoil recommends never stacking helicoils and never putting loctite on them. What would you recommend? Also in the videos I watched it shows the tang being broken off the helicoil after it’s driven on. I wouldn’t want that to fall into the engine.
Red Loctite should be considered non-removable.(without heat)
Blue Loctite is meant to be removable.
If you have it on hand, I don't think it would be a bad thing to seal and lock the insert into the aluminum. You should be able to grip and break the tang with needle -nosed pliers.
I just went out to my garage and checked the factory fasteners holding the fuel pump on an original 340. They are both 3/8-16 UNC hex head cap screws without lock washers or flange heads. The rear is 1-1/4" long and the front is 1-1/2" long. And yes, the rear screw came out with engine oil on it.
Split lockwashers are a bad thing, never used on high quality assemblies. You will not find a single split washer on aircraft or space vehicles because they must be built to Mil-spec. Also, all threaded holes in aluminum MUST have thread inserts. (Keensert type, not Helicoil)
If you need to buy new hex head cap screws, don't fall into the trap of buying Grade 8. You could never torque a screw enough to take advantage of its strength when threaded into aluminum. Grade 5 is good enough mostly because the quality will be better than Grade 1. Always avoid using the cheap unmarked hardware. Not only is the steel of questionable quality,
(that junk shouldn't even be considered steel) but the threads will be poorly formed. A loose fit will only add to your leakage.
You should seal the rear screw threads at insertion to prevent oil migration. I use this stuff to seal threads on engines.
