JB Weld on Exhaust Manifod - bad idea?

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Hi all, it turns out I may have a cracked exhaust manifold on my '99 Civic. From searching around on d-series.org it sounds like this is a fairly common occurrence and in fact a lot of drivers simply ignore it for some period of time. It seems like there's a decent seal of the air intake for te interior fan from the engine bay but I really don't like the thought of having a potential leak up there. Other than the proper fix of replacing any parts that may be broken, is it possible to use JB Weld or something similar to make a temporary patch? I had a mechanic tell me to not use that "stuff" because it can catch fire.

thanks for thoughts/opinions!

Greg
 
As is all too common, your mechanic is wrong, JB weld won't catch fire if you throw it in a volcano. Unfortunately it won't fix your exhaust manifold either, it's rated for a max of 600 degrees and it will pop right off.

They do; however, make other products specifically designed for sealing exahust. Check the "goop" isle of your local auto parts store.
 
If you get the cracked area glowing white hot you can weld it. I have down it with Oxy/Act and with a arc welder but you have to get the casting glowing white and keep it like that until the weld is complete so haveing two goes makes it work a lot easier if you do not have a furnace to heat the casting in.
 
Unfortunately, their all a waste of time and money also. Manifold is subjected to such extreme heat flunctuation that no other material will expand and contract at same rate (IT pulls it's self apart in the first place instead of "breaking") that any "goop" will fall off in short order,I. E. days! Try salvage used part.

Bob
 
I have successfully welded cast iron exhaust manifolds by arc welding them with nickle alloy electrodes in a plain old AC arc welder. I didn't do anymore preheat than heating the area with a propane torch.

Look for arc welder electrodes for welding cast iron.
 
Originally Posted By: alreadygone
Manifold is subjected to such extreme heat flunctuation that no other material will expand and contract at same rate


While I haven't actually tried any of these products, I believe there are some that remain flexible, sort of like heavy duty RTV.
 
Quote:
I have successfully welded cast iron exhaust manifolds by arc welding them with nickle alloy electrodes in a plain old AC arc welder. I didn't do anymore preheat than heating the area with a propane torch.

Look for arc welder electrodes for welding cast iron.

Works just fine. The only downside is that the nickel rod is expensive.
 
thanks for the good replies all.

Wish I had a welding setup though it should be pretty cheap to take it to a welding shop.

I might give the Goop-type stuff a go just out of simplicity and laziness. If it works, I'm out a bit of time a a few $$ and if not, it was busted anyway. Also would be interesting to see if there really is something that can hold up to the temperature swings especially once winter is here.


BTW the way I found that there may be a leak was that when giving the car a Seafoam treatment this week, there was a lot of smoke from the front of the engine that kept coming after the engine was off. Also, obvious splatter of SOMEthing on the block that wasn't there before. Kind of funny but kind of freaky too.


Thanks again,

Greg
 
Originally Posted By: johnd
Quote:
I have successfully welded cast iron exhaust manifolds by arc welding them with nickle alloy electrodes in a plain old AC arc welder. I didn't do anymore preheat than heating the area with a propane torch.

Look for arc welder electrodes for welding cast iron.

Works just fine. The only downside is that the nickel rod is expensive.


wow, about $30/lb at McMasterCarr.
 
1 New or used manifold
2 A smart and careful welder
3 There are exhaust high temp sealers that may work, at least for a while - look in the muffler repair section at the auto parts store. Cleanliness and proper dry time is essential. Wrapping or capping the repair is best.
 
The only problem with used is that you really have to check the part out to make sure it is not also cracked.The Geo Metro 3 cylinder has the same issue and I had a heck of a time finding one that was either not cracked or had a short enough crack that I could actualy weld it and expect it to hold.They would crack at the collector so it was a structural thing as well.
 
Originally Posted By: Horatio
thanks for the good replies all.

Wish I had a welding setup though it should be pretty cheap to take it to a welding shop.

I might give the Goop-type stuff a go just out of simplicity and laziness. If it works, I'm out a bit of time a a few $$ and if not, it was busted anyway. Also would be interesting to see if there really is something that can hold up to the temperature swings especially once winter is here.


BTW the way I found that there may be a leak was that when giving the car a Seafoam treatment this week, there was a lot of smoke from the front of the engine that kept coming after the engine was off. Also, obvious splatter of SOMEthing on the block that wasn't there before. Kind of funny but kind of freaky too.


Thanks again,

Greg


If you want to goop it or glop it go for it. If you want to have it welded, that's worth a shot also,,just don't take it in for welding AFTER goop/glop!!! Any welder worth his pay will tell you where to stick it with that [censored] in the pores of the metal.

Yes, I've welded manifolds also. Some with nickel, some with plain old wire welder. Just can't get success ratio high enough to justify charging customers for my time (ain't doing it for my health or entertainment) If you're a reasonably good amateur it's a lot of fun and ocassionally rewarding challenge. If not, put the money toward replacement part.

Bob
 
This also happened to our 1998 Civic and I just decided to buy an aftermarket exhaust manifold for $75

Ours had a 3 inch hair line crack. If you do get your manifold welded, be prepared to have it rewelded in th e future.
 
For what it's worth, my Jeep has had a cracked exhaust manifold for at least 4 years now. I have no plans to fix it. It just makes the engine sound better...
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You can weld cast iron by stick or oxy. Use nickel allow. Must preheat for best results.

Exhaust gas is corrosive and under high pressure . Would likely blow out any kind of goo.

JBWeld would simply melt at high temps. I tried to fix a broken hinge on an aluminum gas grill top. It got to temp and the hood fell off after the JBW melted.


$.02
 
I did the temp JB weld thing when I was driving across the country once. It worked for about 1,000 miles then blew off. When I got back home I cleaned up the area with my angle grinder, preheated the manifold to 500F and tig welded the crack using 308 stainless filler rod. This was 3 years ago and the repair is still good as new.
 
It's always a good idea to drill 1/8" holes at the ends of any cast iron crack before welding. That way the crack won't grow from heat expansion.
 
Leaky exhaust will throw the O2 sensor off. You'll waste enough gas in time to pay for a new manifold.
 
I tried JB weld on my wife's 93 corolla exhaust manifold, it lasted maybe 3 days before burning off. Replaced the manifold with a new one. Few years later this one cracked, welded it up & this is still holding.
 
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