Bernzomatic Torch - How effective on rusted exh manifold studs?
 

Anyone frequently use a Bernzomatic for siezed bolts, etc.?
I don't own one but I have a rusted exhaust headpipe/converter that I'd change myself IF I can get the studs out of the manifold flange while lying under the car. Already snapped one of the two off where it goes through the spring and I don't really want to break the other one off if I end up having to drive the car somewhere to hire it out.
I think I have room enough to get a torch tip close enough to HEAT the flange ears where the studs go through, then hopefully twist them out with vise-grips. An acetylene torch would be ideal, of course but I don't have that luxury. I'd be willing to invest in a Berzomatic torch if you guys think it will get the metal HOT enough to do the trick. It would also allow me to purchase my own exhaust parts a lot cheaper than any shop is going to charge me., because surely they will all frown on installing customer parts.
It's a flex-pipe and converter pipe on an '04 Honda. The only thing that actually rusted out was the flange plates where they bolt together. But the manifold connecter bolts rusted down to a pencil lead.
I kind of need to know ASAP, because I'm getting this car ready for my sister to use since she retired from over seas.
Much appreciated.

I have use bernzomatic in the past, but MAP gas gets hotter, so I switched to that. Nowadays I use oxy/ acetylene.
I couldn’t tell you if it would work in your case or not, but get the MAP

x's 2 for map

Was just looking online at prices for the torches/cylinders. That was my next question: What's the difference between the MAP and the blue bottle type?
Figured the MAP might work better because it gets hotter(?) The part where the studs are seized are 'ears' so hopefully they will heat up enough.

Harbor Freight doesn't even sell the cylinders evidentley. That's OK. Their torches are probably cheap as hell. I'll probably get what I need at Orielly's.

map is hotter and most any hardware store will have it.

Home Depot. Plumbing section.

I use a compact (and cheap) propane/oxygen setup that's as almost as useful as oxy/acetylene. It uses a 20lb. oxygen tank and a 1b. disposable propane tank, with a very small torch. I've used it to heat a bearing race that was frozen onto a pinion shaft of a 9" rearend, etc.

Other than heating up times, there isn't too much difference between the two. The blue bottle (Propane) is about 3600F while the yellow bottle (MAP-Pro) is about 3750F. The old MAPP gas was the stuff and was 5300F.

i didnt know the newer map was cooler...good to know.

Having done exhaust work for years, the sure fire way is going to be oxy acetylene. All heat helps when doing exhaust work, but propane torches just doesn't generate the amount of heat needed to seperate cast iron from cold roll fasteners consistently.

One trick that sometimes works when you don't have an oxy acetylene torch, is to heat the unit as hot as possible with a lesser heat source, then use a squirt water bottle to quench it quickly. The rapid shrinking will sometimes break the rust bond between the cast iron and cold roll fastener. It doesn't always work, but it's gives you some advantage over cold disassembly.

Shocking the end of the fastener with a drift, and a BFH also will help to release a rusted joint.

There is a reason exhaust shops use oxy acetylene over every other type of torch, they're the professionals, and they absolutley have to get rusted exhaust systems apart as quickly as possible. Having tried about everything there is, over decades my first choice is oxy acetylene.

There is a new player on the market over the past decade, or so. It's called induction heating, and uses a electric iron to heat bolts red hot. I've never used one, but have watched you tube videos, and they seem to do a good job. Less expensive than an oxy acetylene rig, but more than a propane torch.

:2cents:

That induction heating idea sounds pretty intriuging. I'll ask about it if I go to Home Depot this week.
Did a walking tour of the local Harbor Frieght that just opened a couple weeks ago. The only decent looking propane torch they had was $50. Oriellys had a decent one I was willing to spring for but it was an order only item that I'd have to pay UPS shipping on top of the $35.
One thing I was surprised to see at HF was they had a pup sized Oxy/Acetylene torch rig with gas filled cylinders. $350. That might be worth it if I used it once or twice a year. I don't see that happening though.

I remember a guy telling me about busting frozen brake caliper bolts loose with the heat/cold water trick. I wonder if there is a risk of cracking the manifold if I did that on my sister's car? I think if I could accuratly direct the stream of water to the bolt stem.
Looking at it again yesterday, I am a little worried there isn't much left of the stub to get ahold of with vise grips. And I can't really test that without the pipe and lower collar dropped down.

Appreciate all the suggestions and ideas.

I’d take it to a shop that deals with exhaust issues all the time.

They’ll blow that broken stud out of that manifold with an oxy-acetylene torch in a jiffy.

Spending money on whatever heating method is a waste, don’t throw money at it when you’re not sure how to go about it. Just pay the man and let the pros handle it. I don’t see an issue with you purchasing the parts yourself to save some dough as long as you’re supplying quality parts, just tell them you started the job and ran into a snag.

Know when to hold ‘em and know when to fold ‘em.

You can buy oxy/ace torch set very cheap. It will work well enough for occasional use and you will wonder how you ever got along without it. Get the small tanks on an exchange basis and you never have to worry about them. Just drop off the empty and get a full one.