Hey guys,

I've been chasing down an exhaust leak. I pulled the turbos and the manifold and found that three of the four holes for the studs that hold the manifold to the engine were stripped. The holes in the rotor housings for the studs were stripped.

I tried retapping the holes with the same size tap. That allowed new studs to go back in smoothly, but they won't hold the 50 ft-lbs of torque, so it looks like I'll have to use some helicoils to fix the threads. So, I have three questions:

1. Any problems using helicoils in the rotor housings (heat related problems are the main thing I'm worried about)?

2. Anyone used the Autozone thread repair kits? Are they any different from the name brand Helicoil repair kits?

3. Any local stores carry name brand Helicoil kits? I already tried the local Ace Hardware and they didn't have any.

- Andy

 

Helicoils will be fine there.

NAPA tends to carry all of the Helicoil kits; I'm not familiar with the AutoZone ones so can't comment. If you don't have a NAPA nearby call some machine shops.

 

Well, we had to helicoil two threads on both the turbo and the manifold itself. My friend, Tom, who's a mechanic who works on and races in Formula Mirages and the like says it'll hold up really well. If it works for racecars, I imagine it'll work fine for our RX-7s. After we helicoil'd it, it torqued down perfectly...so it seemed to work really well. I believe Tom got his helicoil kits from NAPA as well, but probably from the warehouse ones.

Here's a few photos of us doing some helicoil work on the turbos:

Grinding the stud off so it's flat.


After grinding.


Positioning the drill bit in the center.


Drilling through the stud.


The stud, after drilling through it. Definetly need a high quality drill bit for this.


Putting the extractor in place (tap, tap)


After getting the stud out, we tapped the threads for the new helicoil. Keep in mind, we had to redrill the hole with the proper drill bit before this. I believe it was a 13/32.


The new threads for the helicoil.


The helicoil and tool.


Screwing in the helicoil.


The helicoil in place...you can see the little piece that you need to break off in the center.


Taaa daaa! All good, and it torqued down great!


A little bit of work...but man...it sure beats buying a new manifold.

 

Or in my case a new engine block ... I found the name brand helicoils at a local NAPA, thanks Damon! I also ordered a stubby drill bit to use since I don't have enough space with a full size drill bit. The stubby bit should be here Tuesday, so may next weekend I can take a crack at this.