Freeing Rusty Fasteners With a Blow Torch

Despite the often-shared advice about not buying rusty project cars, sooner or later you’re bound to encounter one. And those rusty cars are filled with rusty, crusty and cruddy fasteners–the kind that can rarely be loosened, even with chemicals.

There is another option, though: the hot wrench.

We’re not talking about a propane or MAPP torch. While these low-buck torches …

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A rosebud torch is also very useful. 

I presume there is a paragraph in there somewhere about being very aware of where the rest of the fire is going...CV boots, brake hoses, ball joint boots...I've burned holes in all of these, and more.

In reply to Streetwiseguy :

The real lesson is in not immediately putting your hand on the metal surrounding the hot fastener.

Regarding the 'only want to heat one of the mating parts' thing, i've actually had decent luck with ice cubes. Heat both parts, hit one with an ice cube (or any non-flammable spray that comes out cool/cold) and soak the heat out of it to shrink it while the other part is still hot. I also recently learned that when you heat a fastener that's inside of a larger/stronger part, the attempted heat expansion actually compresses the part somewhat and when it cools off it's slightly smaller in the constrained area than before you started. 

I watched a co-worker using a blue tip wrench drop the object of his attention into the pocket of his shirt. He was a smoker so there was also a book of matches in there. 

There was much to be learned from that. 

I get by using a plumbers rig, that being acetylene but no oxygen tank. Cant weld with it, but works fine for nuts and bolts.

I've become a big fan of using a candle with the torch.

Heat the parts up, touch the candle to the threads or end of the nut, wax goes into threads, bolt spins right out.

RevRico said:

I've become a big fan of using a candle with the torch.

Heat the parts up, touch the candle to the threads or end of the nut, wax goes into threads, bolt spins right out.

Likewise, but I quench with Kroil.  Spent a long time working on rusty cars in Detroit area, now spoiled in PNW.  I just did a tie rod change on my wifes minivan which was a rust belt car in the past.  Used propane, wrenches, cheater bars (completely unprepared) and half a sunday but got it done.

I have a friend who got his start as a auto mechanic at a Midias Muffler shop.  I saw him remove a rusted, broken flush stud in an exhaust manifold by heating the stud red hot with a cutting torch and then blowing out the stud with the O2. All the threads need was a quick clean up with a tap.  

AS for me while I have the torch, gauges, and hoses I don't have the tanks.  When I can access the nut on  a rusted nut/bolt assembly I try to use my nut splitter.

Streetwiseguy said:

I presume there is a paragraph in there somewhere about being very aware of where the rest of the fire is going...CV boots, brake hoses, ball joint boots...I've burned holes in all of these, and more.

LOL.  I happened to be channel-surfing last night and happened to catch an old episode of Big Bang Theory wherein the brainiacs unintentionally set an old van on fire trying to use heat to loosen a lug nut so they could change a flat. 

In reply to 1988RedT2 :

Funny on TV, not so funny in real life.  My BIL was using a torch to heat up and remove leaf spring bolts on his 1967 Mustang years ago.  It seems that he got the area around the front leaf spring eye hot enough to catch something under the back seat on fire.  Needless to say, the car was ruined.  Be careful with a torch, and then be more careful.

In reply to noddaz :

Same, I wish I could say it was an in law, but it was me. XJ Cherokee, using heat to to remove a leaf spring bolt. It worked, but after getting the bolt out I noticed a conspicuous amount of smoke coming out of the windows. Yep, the carpet was on fire. It wasn't even mine. It was a customers car. Luckily the customer was a dairy farmer that didn't really give a E36 M3, and the burnt carpet smell wasn't any worse than the cow E36 M3 it usually smelt like in there.

I watched TWO professional firemen working on getting off a muffler with a torch and they nicked the plastic fuel line. At first it dripped burning gas. The TWO firemen ran around yelling that the car was going to blow. The home owner (a professional FIREMAN) didn't have a fire extinguisher! I grabbed a few handfuls of sand to contain the dripping gas. In the meantime someone had called 911 and a cop arrived and he just looked at the still contained fire that was still pretty small thanks to the sand. The TWO firemen still yelling - IT'S GOING TO BLOW at the top of their lungs! 

I asked if he cop if he had a fire extinguisher - he got it and like an idiot from 20 feet away (A bit to far away) started to spray the fire site. I  grabbed him by the shoulders and got him right up to the car. Fire OUT. Paint job ruined - car OK. The whole thing happened in Hamburg, Germany with a green Ford Capri. True story - TWO firemen! One was the father of my girl friend.

Motto - If you are using a torch on a car - At least have a fire extinguisher especially if you a a professional fireman.   

I've never seen any professional tech use a blow torch to free-up a stuck fastener. Not ever. R&Ring valve guides sure. And yes, you should always have an extinguisher not only nearby, but you should always have second FE at an arm's reach anytime your using a torch in a garage environment.

How do you tell a professional from a hack?

The professional is using the torch to make his life easier, and the hack is fighting with the fastener.

In my last job we'd occasionally get a call to a press to remove a 3/4" flat socket cap screw with a stripped head. After a few hundred thousand parts it would tighten up so bad you couldn't loosen it. I watched them berkeley with it once, eventually drilling the head off then using an EZ out to get it out of the core rod. Next time I took the call and brought the torches. I heated the head red, then shut it off and returned the torches to the shop. By the time I got back it had cooled and I tapped a large EZ out into the head and backed it out with my fingers.

I think the term blow torch went out about the time the Flinstones ended their run in prime time

FMB42 said:

I've never seen any professional tech use a blow torch to free-up a stuck fastener. Not ever. R&Ring valve guides sure. And yes, you should always have an extinguisher not only nearby, but you should always have second FE at an arm's reach anytime your using a torch in a garage environment.

In the rust belt where I grew up (to the extent that I grew up) the oxy-acetylene torch is a necessary and often used tool in any shop.  Mine was the first expensive tool I bought.  I can do inside and outside cuts on exhaust pipe without damaging the part I'm not cutting.  I can cut nuts off without destroying the bolt and on good days I can cut a bolt or stud out of a hole and leave enough material that it can be cleaned up with a tap.

Well, I'll agree that the 'rust belt' regions are probably different. As for the Pro vs Hack cheap shot I'll just consider the source.

Quote: "After a few hundred thousand parts it would tighten up so bad you couldn't loosen it."

Quote: "I can cut a bolt or stud out of a hole and leave enough material that it can be cleaned up with a tap."

I rest my case.

FMB42 said:

Well, I'll agree that the 'rust belt' regions are probably different. As for the Pro vs Hack cheap shot I'll just consider the source.

Quote: "After a few hundred thousand parts it would tighten up so bad you couldn't loosen it."

Quote: "I can cut a bolt or stud out of a hole and leave enough material that it can be cleaned up with a tap."

I rest my case.

Throw me a bone here

FMB42 said:

I've never seen any professional tech use a blow torch to free-up a stuck fastener. Not ever. R&Ring valve guides sure. And yes, you should always have an extinguisher not only nearby, but you should always have second FE at an arm's reach anytime your using a torch in a garage environment.

Come up to eastern Canada, every shop has them. Every shop uses them almost daily.

That being said induction heaters are even more neat. They don't blind you or melt nearby objects. 

MAP and O2 is a much cheaper setup for a garage shop (<$100) and works just as well. Can pick it up at any hardware store.

Streetwiseguy said:

I presume there is a paragraph in there somewhere about being very aware of where the rest of the fire is going...CV boots, brake hoses, ball joint boots...I've burned holes in all of these, and more.

Was welding a crack on a push mower body once.  Didn't realize that the wife had filled the tank before I started (I hadn't told her I was gonna do it, she hadn't told me she was gonna mow) Turned it upside down in order to weld the underside, fuel started to leak.  Took off the welding mask and thought "oh, well.  E36 M3."

We went and got a new mower.

1SlowVW said:

FMB42 said:

I've never seen any professional tech use a blow torch to free-up a stuck fastener. Not ever. R&Ring valve guides sure. And yes, you should always have an extinguisher not only nearby, but you should always have second FE at an arm's reach anytime your using a torch in a garage environment.

Come up to eastern Canada, every shop has them. Every shop uses them almost daily.

 

That being said induction heaters are even more neat. They don't blind you or melt nearby objects. 

I have wanted one of these for a while.  I tried one a couple of years back and it worked really well but at the time they were $$$$.  Another one I saw was an attachment for a leister heat gut that has a piece of metal that attaches to the nozzle that wraps around the bolt/nut effectively trapping the hot air around it.   I have wanted one of those as well but I have never seen one for sale and I almost think it was a homemade attachment.

One other timely (or not ) tip, try to tighten the bolt/nut before you loosen it.....most times it will come right loose. The wax trick works too, but I use beeswax rather than candle wax - works a treat.