Helicoil pulled out of head (pictures)

[TimIacobucci]

I was installing my new ss exhaust studs today as I was replacing the exhaust gaskets which had many horrible leaks. It was all going very well and I got them all in without a hitch. Didn't over tighten at all, just barely snug in the head. I am very wary of tiny aluminum threads.

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So I put the manifold back on and half tighten a nut on the left and right to hold it on. I did the left first, like I said only halfway, then I started to tighten the right a bit more and I felt a weird pop. I look back over at my first nut and the stud has pulled out of the head.

I pulled the manifold back off to find an old helicoil wrapped around my new ss stud with a nice pile of aluminum caked in it's threads.

I also managed to mangle my new exhaust gasket trying to wiggle the manifold off with the gasket stapled to it like that.

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Here is the offending helicoil and the nice new hole in my head.

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So far all I have come up with for a repair is this.

++ BIG-SERT Oversized thread repair kits ++ thread repair kits for oversized holes, previously repaired threads oversized holes

Not cheap or readily available. Does anyone have experience using these timesert thread repairs or have any other suggestions I might be able to try out here?

Also with the gasket tweaked and seperating like that I assume I should get a new gasket right? Or will it smush back together when clamped down and torqued?

The tubular manifold I have has a beefy 1/2" flange and will put a nice clamp load across the gasket. I couldn't figure why the hell some of the manifold nuts where on there so loose allowing it to leak like it did. Well now I know, shitty helicoil repairs in the head!

 

[knochgoon24]

You could always drill and tap the hole in the head to an even bigger size. You'd probably have to drill the holes in the manifold bigger if you did that, but I've done it before.

 

[cbrfrenzie]

I drilled and tapped all my exhaust manifold holes for 10mm x 1.5 bolts. Not only is there enough material there to do so, but you gain a bunch of strength for hanging that bigger turbo off of it. The holes on the top are a tight fit against my manifold, but the bottom and side holes all clear easily. Also, if you drill and tap for a bigger bolt, you eliminate the heli-coil as well!

Stainless and aluminum react to each other, and under high heats and moisture the reaction occurs even quick. So I would recommend using some sort of anti-seize or zinc plated bolts to avoid the bolts seizing in the head in the future. That's my 2 cents

 

[dave99gst]

or you can weld/drill/tap.. next time go with Keencerts FTW !
Thread repair inserts

 

[Jets303]

I used a NAPA kit and its held fine for two years and three turbo setups later. Make sure to use some sort of anti seize or youll just pull the helicoil right out. Hope that helps