Tackling rusty bolts on 2-1/Cat/Muffler

[r55forme]

My recently purchased 87 911 spent a lot of its early life in New York and the underside hardware is definitely rusty. I started to look at replacing the everything from 2-1 back and started looking at the nuts that are so corroded they don't really have six sides anymore.

Being a CA native, I've not had a lot of experience tackling these kinds of issues and looking for some advice. I have treated them with Kroil for several days, and wondering if I put a socket on there and can't get purchase, is my best option to use a small cut off wheel and cut the nuts off? The engine is still in the car so access isn't the best. Are there any other tools worth adding to my rusty nut arsenal as I'm sure every project I will face will involve this same challenge until I have replaced all the corroded hardware.

I've seen induction heaters, small torches, and just wondering what those of you that face this frequently recommend.

Here's a few pics of the heat shield and bolts I'm up against.

Heat Shield (broke the first one)





Thanks in advance!

[$yncro]

Bolt extractor works pretty good for me.
Get them anywhere too, not expensive.

[john walker's workshop]

Oxy/acet cutting torch. 20 minutes instead of all day with other methods. Just slice the bolt head or nut off and punch the shank through.

[PopsRacer]

Inductive heaters are awesome, esp for residential work. I just went through this exact thing, all 9 bolts were very rusty, and hard to get to. I sprayed them with pblaster, heated them to red, worked the wrench a bit, sprayed again.., a couple or 3 cycles usually did it. (Sometimes fewer) Didn't need to hanmer or grind or cut,

[REVerend]

Mine weren’t quite that bad but were still very firmly rusted in place. I ended up cutting most of them off with a Dremel and the reinforced cut off wheels. On one of them the shank of the bolt was still refusing to budge even after both ends of the bolt were cut off and I had to drill it out.

If I had to do it again I now have a pneumatic cut off tool that uses 3” wheels, that would have been much faster and easier than the Dremel.

I was installing a cat bypass and fab speed supercup exhaust. When I assembled I used stainless hardware and slathered on the high temp nickel anti seize. Some people have said the stainless can gall and be problematic but I recently was taking my muffler off (after ~two years) and zero issues, the bolts came off with no problems.

[PopsRacer]

good to hear about the stainless hardware - that’s the way I went as well, for the new washers and bolts. (316/A4) and I am moiunting them with the heads on the ‘far side’ so I can hammer them out someday if needed.

[REVerend]

Originally Posted by PopsRacer

good to hear about the stainless hardware - that’s the way I went as well, for the new washers and bolts. (316/A4) and I am moiunting them with the heads on the ‘far side’ so I can hammer them out someday if needed.

And just to add… there was stainless hardware that came with the cat bypass and super cup but the bolts were all a bit longer than necessary. The way I see it having extra bolt length just means more exposed thread that can potentially have galling or corrode in some way and make it a problem in the future. I picked up a bunch of stainless hardware and used the shortest bolts possible all around. It did make it slightly more challenging to get together but it was really only a few extra minutes. I briefly considered using cap nuts but didn’t end up going that far.

[917_Langheck]

Replaced all that hardware with stainless and antiseize. No worries ever.

[montauk]

I had to cut most of them off my exhaust system as well, though it wasn’t too tough since the engine was already out of the car. I replaced everything with stainless hardware and used anti-seize compound. Just a heads-up: exposed threads on stainless bolts aren’t a concern—the real corrosion happens at the metal-to-metal contact points. I’d avoid using cap nuts; they don’t prevent corrosion and can make it harder to apply penetrating oil to the threads later on if needed.

[brighton911]

Like John W said, oxy/acetylene makes short work of the job. For exhaust work, it's the answer.

[r55forme]

Thanks all! @johnwalker I haven't made the dive into welding and cutting torches, but maybe the cursing will lead to a small torch. Maybe I can find someone locally here in the Bay Area that might lend a hand.

I was planning on stainless, so thanks for all those comments on it working well. I have a small air die grinder, so maybe a small cutting wheel on there will be my fall back. I'll take a stab this weekend and post back. Appreciate all the input and advice!

MJ

[pmax]

Wielding a torch inches from the car lying on your back wearing protective gear could be fun I guess.

Last time I did this, visegrips and elbow grease worked.

Reading about the SS bolts, sounds like using high temp copper anti-seize is mandatory to prevent galling.

[917_Langheck]

If you don't torque your stainless hardware like Magilla Gorilla, then galling really isn't an issue. That said, using Al or Cu antiseize is good practice.

[Mtsurfposse]

You dont need a Torch, just cut them with a 5' grinder. just keep the sparks under control

[r55forme]

Great, thanks for all the advice. I'm not sure I can get my regular 5" grinder in there, but will try a 3" wheel on the die grinder. I've had good success with stainless bolts on other cars with exhaust with a little copper antiseize to make removal easy.

I'll go after the heatshield tonight and see how it goes.

[PopsRacer]

if you live in a woodframe house, or have any concerns about collateral damage under the car from flames or sparks or little bits of shrapnel, I will just recommend the inductive heater again. No flames, very focused heat (just the fastener) and very fast. Look up “eddy currents”. Magical magnetics stuff.
They are also pretty inexpensive.

Have a battle if that’s your thing, I’m just saying there is another way. Cheers

[dtwa]

Why make it complicated? Those are all through-bolts. Two box wrenches will either break them loose or snap them.


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[john walker's workshop]

Gotta have some hex left to so that. Try that with picture #2.

[pmax]

They do crunch up nicely though in that condition with the visegrips.

In a slightly worse shape than #2, you can probably ripped half the nut off with those.

[porschedude996]

May be more effective if you could remove the whole assembly and work on it on a bench.