Stripped Intake Manifold Bolt

[Ominous C5]

After doing the gasket / RTV fix on my LT4, one of the intake bolts would not torque. I suspect stripped threads in the head. Any advice on what size tap / helicoil I need to buy to fix??

Also, what is the right bead size for The Right Stuff sealant. I used the default width of the pre-cut plastic tip, but it seems fairly narrow relative to over RTV.


Thanks,

Eric

 

[Jeffvette]

Take the bolt into a parts store and ask for the helicoil set up for that size. They are not cheap for what you get.

 

[wx briefer]

You may know and do all of this already but may I make a few suggestions? Before installling the Heli-coil you may want to spray a very LIGHT coat of zinc chromate on the insert to help inhibit corrosion from the disimilar metal reaction with the aluminum head. If you don't have any, go out to the local airport and find a mechanic in one of the hangars.

As far as the bead size, just enough to stand up well, don't flatten it, let the manifold flatten it from contact. Also, wipe the metal down really well with acetone before applying.

Don't let the stripped bolt get you down, it will be stronger than before after repair.

 

[lt4 gs]

good catch on the zinc chromate.....go to any aircraft sheet metal repair......just like wx briefer sez

 

[3TT3V]

Locktite the helicoil while inserting it (?). We always use Locktite in our industrial setting into aluminum but I dunno about automotive.

 

[Ominous C5]

I need a new electric drill for this job. I was thinking about a Milwaukee 1/2" 8 amp. Any other recommendations?

Thanks,

Eric

 

[wx briefer]

I suppose any good drill is up to the task. The detail that I would not leave out, though, is the template to make sure the hole is the same angle as the original. Perpendicular is easily effected by use of an oak block of wood drilled through by using a drill press. If it is at an angle to the surface then you will have to get creative to manufacture a good drill guide. Don't try to wing it as it usually doesn't work out too well.