Stuck exhaust fasteners. Any advice?

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I need to separate the front section of an exhaust from the manifold.

It's held by four M10 nuts that haven't been loosened in many years, if at all.

Applied PB Blaster a couple weeks ago in preparation. Applied some more overnight.

They won't budge, using only (non-impact) tools.

Applied some more, tapped it with a hammer. Tried heat with a propane torch, and quick quench with some water. The only trick I haven't tried is candle wax.

I don't want to snap the manifold studs and have to replace them as well (they're tack welded in place), so I decided to quit while ahead.

Thinking about taking it to a pro (exhaust shop) and having them break them loose for me. Impact, hotter torch, experience; I expect they can do a better job than me.
 
I've had the best luck with lots of heat and an impact. More heat than you can generate with a propane torch. Oxy-acetylene is really a must to generate the heat required. Heat it good and red, then as the color goes away hose it down with either a penetrating lube or candle wax. No guarantee it won't still break but it's what I've had the best luck with. Be careful not to apply penetrating oil if it's still to hot or it'll auto ignite.
 
I think heat is really the only option since it is an exhaust manifold. Get it as hot as you can before you try to unfasten.
 
Originally Posted By: FlyNavyP3
Oxy-acetylene is really a must to generate the heat required. Heat it good and red,


Correct, nothing less will do.

Many exhaust shops will just blast the nut off with a cutting torch, it usually leaves the studs thread intact.
 
Thanks all.

The more I look into this, it's apparent that is a pretty common problem, and a lot of heat is required; more than I can generate.

I did come across a neat induction heater, Mini-Ductor, that seems to work pretty well without flame. Pricey tool for a DIYer, though.

I'll let a pro handle it. Beats being under the car swearing for a few hours.

Already have new nuts so I don't care what happens to them; I just want to preserve the studs and not open another can of worms.

Not having done much exhaust work, I wonder if any anti-seize is called for, or used in such applications upon reassembly? It would seem to be a natural.

I have some copper-based stuff, and will use it, but will it help down the road?
 
When I worked at the service station, the mechanics used an oxy-acetylen torch to get the nuts red hot (and by red hot, they were glowing orange). Then, while glowing orange, you'd use a simple ratchet with an extension. They came right off. They'd make a squeek, squeek, squeek of protest, but no matter how badly they were rusted on, they'd come right off. Oh, and don't step on the nut when it drops to the floor, it will embed itself in your work boot.
 
Originally Posted By: Carmudgeon
Thanks all.

The more I look into this, it's apparent that is a pretty common problem, and a lot of heat is required; more than I can generate.

I did come across a neat induction heater, Mini-Ductor, that seems to work pretty well without flame. Pricey tool for a DIYer, though.

I'll let a pro handle it. Beats being under the car swearing for a few hours.

Already have new nuts so I don't care what happens to them; I just want to preserve the studs and not open another can of worms.

Not having done much exhaust work, I wonder if any anti-seize is called for, or used in such applications upon reassembly? It would seem to be a natural.

I have some copper-based stuff, and will use it, but will it help down the road?


Next time try ( if accessible) spraying over a week or so penetrating oil. Then put a blunt point on an impact air chisel. Put tip o where it won't distort ssl,rthing important and let it bounce all over. Vibrates [censored] out of and loosens rust sometimes better than cherrying. Better on huge castings tat wick the heat away quickly. Spray some oil, rinse and repeat a few times.
Another trick is take air gun or even a drill driver for screws to it. Don't muscle [censored] out of it or it'll snap. Just ride it back and forth tightening and loosening it slightly. If it moves a smidge either way you have it licked. If it moves back then starts to bind hard tighten back some and clean exposed threads with wire wheel , thread chaser, die, dremel wheel anything.... as for torches oxy propane works as well as acetylene .
As for getting ready for next time try Milk Of Magnesia. I read someplace they used it on B52 engine hot sections .
 
Give it a last try of heating with your propane torch and then cooling it with sprays of PB Blaster.

Then try and loosen or tighten with wrench.

As others have said, an impact maybe needed and or oxy/acetylene torch.
 
I have a little cold chisel that I keep very sharp. I use it to split nuts. Also are the nuts large enough to use a drill on a flat to weaken it?
 
Every time I do exhaust work I always start with a ratchet and socket. Rarely does that work. So I go to the impact and it takes the nuts right off. Haven't damaged a stud yet

Don
 
You need to get them orange hot, than quickly get on them with an impact at full power. That's always how they come out for me. Worst case scenario would be to cut it off with oxyacetylene and put new head studs in. Doesn't sound like you have too much of a choice. Especially if your cat is built into the manifold and you can't pass emissions without it.
 
Originally Posted By: The_Eric
Oxy/acetylene torch and an impact. Pretty much wasting time otherwise.


Yup. Would not think of doing exhaust work without torches.
 
BMW exhausts were the best I've ever seen. The front section was attached to the ex manifold with 6 10 mm nuts that were copper 14 mm hex. They were formed in such a way that there was not full 360' thread to thread contact. They worked great! The studs on the Rat are long gone. Replaced by grade 8 3/8 bolts with double long brass nuts.
 
Originally Posted By: Carmudgeon
I need to separate the front section of an exhaust from the manifold.

It's held by four M10 nuts that haven't been loosened in many years, if at all.

Applied PB Blaster a couple weeks ago in preparation. Applied some more overnight.

They won't budge, using only (non-impact) tools.

Applied some more, tapped it with a hammer. Tried heat with a propane torch, and quick quench with some water. The only trick I haven't tried is candle wax.

I don't want to snap the manifold studs and have to replace them as well (they're tack welded in place), so I decided to quit while ahead.

Thinking about taking it to a pro (exhaust shop) and having them break them loose for me. Impact, hotter torch, experience; I expect they can do a better job than me.


How many times do we have to tell you guys....heat, heat, heat. And I am talking acetylene heat to red. Propane won't do.
 
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