Heli coil failed

[Ces4rDSM]

I had to instal 2 heli coils for my exhaust manifold studs due to the fact that the threads broke on the 2 holes, my first heli coil did fine that is until I took my exhaust mani off and reinstalled but both heli coils ended up losing tension when I torqued the bolts. Now it looks like every time I torque, the studs appear to come out of the hole again. Same problem. Now how should I repair ?

 

[mitsubishikid]

send it to a machine shop and have them weld shut and then have it re-drilled and tapped to
metric 8x1.25 it will not be cheep but it can be done. depending on how much you have invested in the cylinder head, you might consider finding another head, especially if it's a mostly stock head.

 

[silvreclips]

You can try a different type of insert if you have enough material around the hole. Keenserts have a larger OD so you can drill it and retap that hole again.

 

[Vegas Smith]

Worst case scenario is you can drill to a larger size such as 10x1.25. You would of course have to drill out the exhaust manifold holes for 10mm as well but that's not hard.

 

[AWD-Tony]

Vegas’s method would be the cheapest way to go

 

[Ces4rDSM]

Damn, I'm getting to the point where I might sell the car and keep the engine. I dont have the space to always work on it and it just takes so much patience.

 

[AWD-Tony]

Can’t count how many helicoils I’ve installed over the years. Prob over 10 on just my current dsm and never had an issue with it coming loose. Is it possible you used too big of a drill bit? Think I’ve installed 4 for the exhaust manifold and a lot for the valve cover.

I get your frustration and hope you get this sorted.

 

[Ces4rDSM]

To be honest with the amount of space I was working with, and the time on my hands the heli coils were done decent. My guess is the threads holding the heli coils broke. Or maybe I torqued the bolts too hard. I was torquing the bolts to 28 lb of pressure

 

[AWD-Tony]

Think it’s 18-22.

 

[Ces4rDSM]

That's probably why. 22 lbs felt too little for me so I usually torque them to 25 lbs but this time i went 28 lbs

 

[AWD-Tony]

The a

That's probably why. 22 lbs felt too little for me so I usually torque them to 25 lbs but this time i went 28 lbs

Probably. The aluminum used to cast these heads weren’t the best.

 

[Ces4rDSM]

Yea but my torque wrench has a min torque value of 25

 

[Ces4rDSM]

Yea what's your recommendation? Sell the shell and keep the motor for future swap ?

 

[AWD-Tony]

Yea but my torque wrench has a min torque value of 25

I use harbor freights. It’s only $15ish

 

[AWD-Tony]

Yea what's your recommendation? Sell the shell and keep the motor for future swap ?

Idk...

 

[Ces4rDSM]

Mitsubishikid I hadn't seen your post! I think ima end up doing so. Does anybody know how much it adds up to in cost by retapping the holes after welding them ?