[vr6swap]

A friend gave me a turbo manifold a few years ago. All the turbo mounting studs were broken off flush with the flange, and whoever tried to drill out the studs used a hand drill with kinda not too great results. Even if you could finish drilling / retapping the holes I doubt they would line up with the turbo.

Since I have this manifold and don't have any money in it, I would like to repair and use it. My idea was to drill out the holes and maybe use a countersink or a step bit to bevel them out, weld the holes closed or almost closed, then re-drill them on a mill and re-tap.

I have access to a media blasting cabinet to clean it up, and a gas grill to pre-heat it prior to welding if need be. I have read about a MIG wire made specifically for repairing cast iron, is this what I need here?

[WerkSpace]

I would start by heating it up with a gas torch, then using a left hand drill bit.
http://www.youtube.com/watch?v=FYvaPbX1sT4

The reason for heating it up, is to break down the corrosion.
Rust can expand to 15 times its size as compared to steel.
Rust can also generate pressures up to 70,000 psi.

[BAP]

I agree with heat being a solution to freeing rust corrosion. Your observation that the previous attempt to drill was none too accurate would lead me to suggest that rather than any attempt to weld full and re drill might be better suited to placing a flat washer similar or smaller in size as directly over the broken stud as possible. Mig weld the washer to the stud avoiding getting any penetration outside the of the original threaded stud. Weld a nut on the washer and let red cool out. Gently work the stud back and forth to remove. The heat from welding will expand the stud and separate the rust to free the stud.

I have been successful with this method over the years. Sometime it takes more than one attempt but it is not often this will fail.

As for the manifold repair... Manifolds are intended to maintain their dimensions and integrity by being bolted securely to the block and in your case the turbo as well. Excess heat to a free standing manifold not applied evenly can result in unrepairable twisting or other distortion. I have always taken the time to securely bolt a manifold to a substantial flat plate before heating and in particular welding in a given area.

Experience learned in years of tractor pulling when turbo pressure and excessive heat exceeded the integrity of cast manifolds. Good luck bap

[vr6swap]

Will try the washer / nut method and see how it goes.

Since at least one of the holes is pretty well dicked up from previous attempts at repair, I'm pretty sure some kind of fill and drill procedure will be neccessary before the manifold can be used again.

Getting the broken off studs out is a good place to start though, so thanks for the input.

[Alexa]

Bap.
Tanks for the washer/nut method.
Alexa

[Otto Nobedder]

Are these studs in blind holes? Or on a flange?

I ask because, once the studs are removed, the threads may not be suitable for re-use, and it would be nice to be able to ream them to the OD, and use through-studs.

Just a thought...

Steve S

[BAP]

An after thought to Steve S post ...unless you have a very large heavy defuser on the exhaust side of the turbo you might consider remounting with stainless bolts, no future rust issues. Just remember stainless bolts are often just grade three soft bolts, easy to drill and easy to twist off as well, but no rust. bap

[weldin mike 27]

Hey,

Jody has a video on stud removal , from below the surface . However, his technique needs skills of Einsteinian proportion .

Mick