Maybe try this: HTS-528 Brazing Rod at
HTS-528 The strongest brazing rod made for joining cast iron and steel
HTS-528 The strongest brazing rod made for joining cast iron and steel
Exhaust manifold crack - braze or ??
- Thread starter dstig1
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westcliffe01
Veteran Member
I suggest you don't bother trying to re-weld or braze the manifold. Those parts run too hot for brazing and the material in those manifolds is quite an exotic alloy to resist the heat. Any form of cast iron is not supposed to be able to stand up to that kind of service forever so it is just a question of time before they fail. Now that it is cracked, you have a serious stress concentration and even if you removed it for full access and had a genius weld it, it is likely to fail again in the same place very soon. Most likely, it will crack immediately after welding. Trying to weld it in situ is a particularly hazardous undertaking.
The gas temperatures in that part of the manifold run over 900C or about 1650F. The catalyst is probably deactivated by now anyway. If I was you, now is the time to get a set of header pipes for that engine. This site http://www.carparts.com/details/Honda/Civic/Pacesetter/Headers/1998/P40701160.html?TID=80000000CP-cppahe98hondacivic19922000pacesetterp407011601171636&origin=pla&CP=1&CP_SRC=PPC&gclid=CISjnND0s7MCFQVgMgodnWQA3Q lists a header for your car for $144.
If you feel environmentally conscious, you can fit an aftermarket generic 3 way catalyst after the header and the exhaust shop can weld you in a new boss for your O2 sensor. With the crack in its current position, the air leak will probably cause the engine to run rich and thereby increase your fuel consumption. By now the O2 sensor must be toast anyhow.
The gas temperatures in that part of the manifold run over 900C or about 1650F. The catalyst is probably deactivated by now anyway. If I was you, now is the time to get a set of header pipes for that engine. This site http://www.carparts.com/details/Honda/Civic/Pacesetter/Headers/1998/P40701160.html?TID=80000000CP-cppahe98hondacivic19922000pacesetterp407011601171636&origin=pla&CP=1&CP_SRC=PPC&gclid=CISjnND0s7MCFQVgMgodnWQA3Q lists a header for your car for $144.
If you feel environmentally conscious, you can fit an aftermarket generic 3 way catalyst after the header and the exhaust shop can weld you in a new boss for your O2 sensor. With the crack in its current position, the air leak will probably cause the engine to run rich and thereby increase your fuel consumption. By now the O2 sensor must be toast anyhow.
OP
dstig1
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I picked up some of the Thermosteel stuff to give that a try. They actually had a different brand, but looks like the same basic stuff. I won't be able to get to it for a week or two though.
I disagree that it is not worth repairing. I'm not sure how much longer this car will last so I don't really want to dump money into it if I don't have to. A cheap fix here is worth trying, IMHO. I think I've been living with this crack for a few years already, without realizing it, so it's not going to get any worse if I try to patch it. Removing the manifold is a recipe for disaster as I'm sure I will have to extract studs that snap off. If I can avoid that major headache, I'm all for it.
Westcliffe- Most exhaust manifolds are really just basic cast iron, nothing exotic. This is not a turbo engine, so it does not need anything special.
I disagree that it is not worth repairing. I'm not sure how much longer this car will last so I don't really want to dump money into it if I don't have to. A cheap fix here is worth trying, IMHO. I think I've been living with this crack for a few years already, without realizing it, so it's not going to get any worse if I try to patch it. Removing the manifold is a recipe for disaster as I'm sure I will have to extract studs that snap off. If I can avoid that major headache, I'm all for it.
Westcliffe- Most exhaust manifolds are really just basic cast iron, nothing exotic. This is not a turbo engine, so it does not need anything special.
westcliffe01
Veteran Member
Dstig1, that is exactly what consumers think, but it so happens that I have worked in that specific field (making exhaust parts) since 1998, so I am pretty confident that I know what I am talking about. GM pressurized their manifold casting suppliers so much in the 2000-2005 time frame that many of the casting houses went bankrupt and the few left raised their prices dramatically. So the whole thing backfired on GM because the cheap competition got eliminated.
I do not think the situation with the attachment bolts looks too bad from the few pictures you had posted. The key thing to remember is that everything is dry and has oxidation. If you rotate a fastener 90 degrees, apply some more penetrating oil/ kroil and let it wick in. Don't just try to crank fasteners out in 1 go. They get hot, gall and then seize. Order replacement fasteners from the dealer before you start, never try to re-use them. I think that $150 for a replacement part on a car that has given you good service for a long time is a good investment. it is entirely possible that you can get another 100k out of that engine, so why not ?
I do not think the situation with the attachment bolts looks too bad from the few pictures you had posted. The key thing to remember is that everything is dry and has oxidation. If you rotate a fastener 90 degrees, apply some more penetrating oil/ kroil and let it wick in. Don't just try to crank fasteners out in 1 go. They get hot, gall and then seize. Order replacement fasteners from the dealer before you start, never try to re-use them. I think that $150 for a replacement part on a car that has given you good service for a long time is a good investment. it is entirely possible that you can get another 100k out of that engine, so why not ?
yomax4
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Brazing materials, expand and contract at way different temps than the cast. Soon you will have anonter leak. I would bet just about anything that no epoxy base material will work due to the same reasons and also due to the fact that they are epoxy based.
westcliffe01
Veteran Member
I'd like some of that 1800F epoxy myself... It must be the same stuff that was used on the Apollo heat shields....
Scooby074
Super Member
Id pull it and braze it.
If it broke again, id throw a cheap new or used manifold on it. Honda's are a dime a dozen so parts are readily available new or used at every price point.
If it broke again, id throw a cheap new or used manifold on it. Honda's are a dime a dozen so parts are readily available new or used at every price point.
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dstig1
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Well if it's not cast iron - then what is is, and why does a magnet stick to it?
I'm well aware of how to deal with rusted fasteners living up here... And the place to start is by chasing the exposed threads or wire brushing them so the fastener can come off cleaner. And then rounds of penetrating oil, going slowly as you noted, and heat as required. It's still a crap shoot. And the rest of the car will succumb to rust long before the engine is an issue. I doubt this car has more than 3-4 years left in it due to rust.
No epoxy can handle these temps. This stuff is something different that is made for this job and rated to 2400F. For $8 and a little bit of time, I don't think I can lose at this point... Worst case I have to pull it off and replace the manifold, but that's right where I am anyways. I read several people's reviews of this stuff in various forums and all but one said the stuff held up great for a long time in this application. It's worth a shot...cheap and easy to try.
Yomax - you are probably right about the brazing materials and I didn't think about that. Brazing is often used for cast iron repair, I know, but then that usually at room temp so the expansion isn't the big issue.
I'm well aware of how to deal with rusted fasteners living up here... And the place to start is by chasing the exposed threads or wire brushing them so the fastener can come off cleaner. And then rounds of penetrating oil, going slowly as you noted, and heat as required. It's still a crap shoot. And the rest of the car will succumb to rust long before the engine is an issue. I doubt this car has more than 3-4 years left in it due to rust.
No epoxy can handle these temps. This stuff is something different that is made for this job and rated to 2400F. For $8 and a little bit of time, I don't think I can lose at this point... Worst case I have to pull it off and replace the manifold, but that's right where I am anyways. I read several people's reviews of this stuff in various forums and all but one said the stuff held up great for a long time in this application. It's worth a shot...cheap and easy to try.
Yomax - you are probably right about the brazing materials and I didn't think about that. Brazing is often used for cast iron repair, I know, but then that usually at room temp so the expansion isn't the big issue.
Scooby074
Super Member
Interesting stuff. It doesn't appear to be epoxy by looking at the MSDS.. It looks like its actually silica gel. Very curious.
I wonder if it will penetrate the crack and bond? Or gel up on the surface? Ive never seen a product like that.