Repairing damaged manifold stud and smoothing surface

[JHZR2]

This is a follow up to a few related threads, as I think this is a specific skill and technique so best left separate to address. The manifold on my 1991 MB300D has a bit of erosion at the turbo interface.

The manifold is cast iron. The studs I believe are stainless. All the hardware came apart very nicely after 230k miles. Thing is, I cannot get the four studs out.

Two I can see on the backside, two are blind holes.

I’ve tried months of penetrating oil. I’ve tried double nutting, which just spun. I’ve even just tried inductive heating, but I couldnt get the stud hot enough, and if I put nuts on, they would glow red but the studs wouldn’t. Too good of contact and too much thermal mass on the manifold.

I have a Lisle stud remover, and a Hazet. I think the Hazet is better as it has a three-sided contact. But I can’t apply enough torque to it regardless to get the studs to move.

Each time I tried, I chased the threads.

But after a few times trying the stud remover, trying the double nut with heat, etc., the one stud I was working on looks like this:

One that is not as damaged looks like this:

Which I used a remover on only once. The studs are M8x1.25.

So now I’m in a pickle. I think I need to re-cut threads on the stud. The chaser goes on just fine. A real nut will not go on at all. Im not keen on removing material, but I think that’s the only hope besides attempting to drill out the stud from both sides.

So, what to do??

Then, since I can’t get these studs off, what is the best bet to clean the manifold sealing surface flat?

There is a bit of erosion.

So, recommendations?

Thanks very much!

 

[The_Jeff]

Some of the guys at work make stud extractors out of a nut and a pair of vise grips.

Weld the nut to the jaws of the vise grips, both sides.

Cut a slit in the nut using a bandsaw or a "1mm" cutting wheel.

Clamp this device around the stud you want out. The missing metal from the cut will let it clamp more closely.

 

[D60]

You need to weld a nut on there, period. That heat alone from a good rosette weld might be enough.

If not, you need a big rosebud on the blue wrench. Heat the manifold flange where the threads are. Use an impact with discretion to "shock" it loose. I'd probably start with a 3/8" impact wrench as it's less likely to snap a 5/16" fastener

You've already got this on the bench so just carry it to a shop that can do the hot works as I think I always tell you to get a welder and you always say you don't have a welder.

For your surface height issue, maybe a stationary belt sander. Ideally you'd have it machined.

 

[Trav]

You need an oxy acetylene torch to really get that part of the manifold red. Here are a couple of less expensive ones, these are good enough to do most jobs you need a torch for.

https://www.harborfreight.com/portable-torch-kit-with-oxygen-and-acetylene-tanks-63736.html

https://www.tractorsupply.com/tsc/p...3-complete-torch-outfit-with-cylinder-3809429

 

[JHZR2]

Some of the guys at work make stud extractors out of a nut and a pair of vise grips.

Weld the nut to the jaws of the vise grips, both sides.

Cut a slit in the nut using a bandsaw or a "1mm" cutting wheel.

Clamp this device around the stud you want out. The missing metal from the cut will let it clamp more closely.

Interesting approach. Makes a lot of sense since it will keep the threads proper and probably always have a perfect fit and easy on/off on hot studs.

 

[JHZR2]

You need to weld a nut on there, period. That heat alone from a good rosette weld might be enough.

If not, you need a big rosebud on the blue wrench. Heat the manifold flange where the threads are. Use an impact with discretion to "shock" it loose. I'd probably start with a 3/8" impact wrench as it's less likely to snap a 5/16" fastener

You've already got this on the bench so just carry it to a shop that can do the hot works as I think I always tell you to get a welder and you always say you don't have a welder.

For your surface height issue, maybe a stationary belt sander. Ideally you'd have it machined.

lol you have said and I need to learn. But this is stainless in cast iron. Does that matter too?

What is a big rosebud? And is blue the right stuff? I can’t even solder copper to brass valves well with propane anymore as it’s not hot enough.

Since double nutting has always slipped, what do I use to get enough grip using the impact? Something like my Hazet extractor?

 

[D60]

lol you have said and I need to learn. But this is stainless in cast iron. Does that matter too?

What is a big rosebud? And is blue the right stuff? I can’t even solder copper to brass valves well with propane anymore as it’s not hot enough.

Since double nutting has always slipped, what do I use to get enough grip using the impact? Something like my Hazet extractor?

View attachment 334601

Your welded nut will have enough grip!

Welding to stainless with mild wire isn't ideal but good enough for this.

But really you need to get that flange

It's more difficult to get cast iron to glow red, but it will for less time and not as brightly as mild steel

 

[Mechanician]

Induction heating the studs is not going to be the best route.
The stud grows in size with heat, you want to heat the hole that it's in to grow.
You're not trying to save the studs, so just a pair of properly sized vice grips should suffice. Once you get the flange around the stud cherry red.

 

[SammyChevelleTypeS3]

I realize you are limited to what one can do without a home shop full of many types of tools , blow torch etc...
We always had best results when Kroil soaking did not work, by putting the heat/torch to the equipment the
bolt was stuck into. Like the manifold. If one could heat it up without harming anything attached they may come out.
You have proven to yourself heating the nuts did not work. Good luck.

 

[RooflessVW]

You could always drill through the stud to relive some tension. Get it hot with the induction heater and shock it with some CRC Freeze-Off and hammer.

You could also cut them off flat and drill them out entirely.

 

[gman2304]

You've already got this on the bench so just carry it to a shop that can do the hot works

^ This.

 

[clinebarger]

Get the stud hot & pour some water on it a couple times, Weld on a nut. It would be ideal to put the manifold in a oven & preheat, Then use a torch to heat the manifold by the stud. Short hits with a impact.

Is a new manifold extremely expensive?

 

[GSCJR]

But really you need to get that flange

a pair of properly sized vice grips should suffice. Once you get the flange around the stud cherry red.

putting the heat/torch to the equipment the bolt was stuck into. Like the manifold.

+1

I learned this as an apprentice. One day, I was walking through the body shop we did mechanical work for, and the body man was asking my boss for help. He had heated a fastener that had seized, but ended up destroying it. I vividly remember my boss explaining to him that it's not the fastener that needs heat, it's the area around it; it feels like yesterday, but that was about 30 years ago. Good luck @JHZR2.

Noticed @Trav mentioned that also: You need an oxy acetylene torch to really get that part of the manifold red.

 

[spasm3]

Id weld a nut on there.

But even if you get the studs out, it still needs to go the the machine shop to resurface down that manifold properly.

I've done cylinder heads with sand paper on a sheet of glass, but your manifolds look like more material needs to be removed, than you could do by hand.

 

[paulo57509]

Since it appears that the manifold is out of the car, would stud removal via EDM be the path of least resistance?

 

[JHZR2]

+1

I learned this as an apprentice. One day, I was walking through the body shop we did mechanical work for, and the body man was asking my boss for help. He had heated a fastener that had seized, but ended up destroying it. I vividly remember my boss explaining to him that it's not the fastener that needs heat, it's the area around it; it feels like yesterday, but that was about 30 years ago. Good luck @JHZR2.

Noticed @Trav mentioned that also: You need an oxy acetylene torch to really get that part of the manifold red.

Yeah, heating the manifold was a consideration. Heating the stud wasn’t my first choice but I figured I’d give it a go since I had the tool. My hope was that the stud would heat the manifold locally enough to either break any corrosion/binding, and let me get it out, and/or get the manifold to expand around the hole too.

Of course it didn’t work.

Id weld a nut on there.

But even if you get the studs out, it still needs to go the the machine shop to resurface down that manifold properly.

I've done cylinder heads with sand paper on a sheet of glass, but your manifolds look like more material needs to be removed, than you could do by hand.

I understand that machine shops use a big belt sander. I have a relatively big one that I was going to start on and then do as you say, sandpaper on glass.

Problem is anymore I can’t even tell what machine shop is worth going to.

 

[bullwinkle]

The guy above that said heating and cooling-I would get out the big oxyacetylene torch, get the manifold as hot as possible, big Vise Grips on the stud, hit the stud with recovered R404A liquid or other refrigerant to shrink it. If that doesn’t work, nothing else will. Then it’s time to grind it flush, drill it, and tap it. Judicious grinding and sanding should be able to get the low spots better.

 

[Chris142]

I hate messing with stuff like that. No matter what I try I just make things worse. My recommendation is to take the part to a machine shop. Have them pull the studs and surface that area.

 

[NibbanaBanana]

You could always drill through the stud to relive some tension. Get it hot with the induction heater and shock it with some CRC Freeze-Off and hammer.

You could also cut them off flat and drill them out entirely.

Sometimes stainless that has been heated and cooled in cast iron gets hard as a tool bit.

 

[bullwinkle]

Sometimes stainless that has been heated and cooled in cast iron gets hard as a tool bit.

Stainless is rough in general, my broken off Taylor door studs take a center punch, a 1/8” titanium bit dead center, stepping out gradually to a bit for a 5/16-18 tap… Or the broken stud bit spins into the front of the machine! My knucklehead co-workers have broken off taps & EZ-Outs off in them, then it’s a DISASTER!