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Welding cracks in iron exhaust manifolds

Kern Dog

Life is full of turns. Build your car to handle.
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I have a pair of 1967 Chrysler TNT 440 exhaust manifolds that have cracks in them. Both are about 1 1/2" long. I've never welded cast iron.
A prior owner filled one with a gold colored material. I don't know much about that but is that the color of Brazing rod? I'll get pictures tomorrow. I was just curious about the difficulty of repairing these. Being C body, does anyone know if they would fit a '70 Charger 383? I understand that the RH side usually fits all cars but the left has the pesky steering column to deal with.
 
From what I know you need to heat the piss out of the cast iron. V groove out the crack and weld it back. Gold colored stuff is most likely brazing rods like you said. It can be repaired with a stick welder and LOTSA heat.

Well, I stand corrected. Here is a link to welding cast with no heat.
 
The casting numbers should be on the manifolds. It is easy go look up what exact years and models will interchange online if you decide to replace it.
 
They will fit....if ordering exhaust then use the casting numbers to get the right pipe......

I would bet that was brazing......
 
I was told by a welder that cast iron needs to be kept cold during welding.
If it just needs sealed and doesn’t need the strength of welding, I would use a torch and a high silver content (56%+) alloy.
 
Call in an expert.
Take them to a shop and ask to see what iron they have welded!!

I knew a welder at work that had 30 years experience. He could weld steel to water!
Seriously, hard to do correctly unless you have many decades experience.
 
For cast iron you would use "Ni-rod" which has a high nickel content.
 
Nickel rod is what you want. The thing is with welding a exhaust manifold is it has gone through many heat cycles and most of the carbon or temper has been lost. Without much carbon being there anymore, it makes the melting, fusion, knitting very difficult. That's why the choice is nickel. It's the best for fusion on cast iron that's suffered carbon loss. It won't be as strong as it was originally but can hold up rather well if it's not a load bearing piece.

The brazing of cast will work also but it's not as strong as the nickel.

@Kern Dog, the brazing on your piece will be a contaminant and has to be fully removed before useing anything else in it's place.
 
I know this is not of this thread but, I have used Ni-rod successfully to build up wear on caliper brackets.
Mike
 
I know this is not of this thread but, I have used Ni-rod successfully to build up wear on caliper brackets.
Mike
I would think caliper brackets are cast steel. You can use any steel welding material to weld it just depends on how hard you want it. A E70 rod or wire would be pretty hard for the wear area. There's even harder material that could be used.
 
Cast iron is not all the same content . Some will weld up great and others like ****. Contaminants will be your worst enemy.I have used spool arc 83 successfully on these corvette manifolds. Some areas are built up an inch thick. 3 seasons on these and no cracks/leaks. These were identical manifolds bought at the same time from the same company.

corv1.JPG corv2.JPG
 
My go-to rod is a Stainless 308 using my SA200. I preheat in the oven to 300 degrees plus, make the weld and return it to the oven, let it heat up again and shut the oven off.
Cooling slowly is important as the 308 and cast cool at different rates, so speed is important to success. If you are carrying it to the oven and you hear a loud "tink", they separated.

Kerndog is correct. The brass has to go, (or be redone).

They make a diamond shaped rod that is used with a gas welder. It's a high nickel rod and works, but I have only used it once and am no expert on it's applications.

Is it a crack, or is it broken in two? If two pieces, I bolt manifolds to a bare head to keep it square while making the weld.

With my Travelall, the manifolds are hard to find and a pain to remove, so I pulled the inner fender to get access. I started the truck warming the manifold, shut it off and made my weld, then started it up again and drove it. Still good 20 years later.
 
Welcome to the 21st Century! When welding cast Iron, especially something small
like an exhaust manifold, I like to TIG weld them with Castolin Eutectic TigTectic 224
Tig filler rod. Go on-line and read the description. I would also pre heat the manifold
according to directions, and also bolt it to a scrap head to keep the bolting face flat.
TigTectic® 224
CastoWig3_3.jpg

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A High-nickel rod for repairing, joining, and building-up of cast iron
Joining and cladding various cast irons such as ductile, nodular, & SG with excellent machinability


Applications
Pump valve seats, engine blocks with surface defects, re-patching large-size holes involving steel-to-cast iron welding, cylinder head cracks between inlet and exhaust ports, touch-up repairs.
 
Hi Kern
C body takes a different driver side manifold
I may have a couple in Los Angles, can check Mid Nov if you have not come up with one do you need matching numbers
the problem with welding cast iron is contamination and rust- you have to get down to clean bear metal
what kerndog says but you can re-braize only has to goif you switch
but were they clean B$ brazing
 
Drill a hole at the end of the crack so it doesn't travel when you start welding. Bevel out the crack. Heat the manifold, weld with a 55% nickel rod, cool it slowly.
 
Don't bother trying to weld them. Welding cast iron correctly requires heating the part and then very slow cooling. Iffy at best. Drill holes at each end. Either braze them with a torch or tig braze. Welding will most likely result in another crack. Currently running a brazed manifold on my Jeep. It's been fine.
Doug
 
Last edited:
WOW! 17 posts so far. Truly a heated subject!
:thumbsup:
 
Welcome to the 21st Century! When welding cast Iron, especially something small
like an exhaust manifold, I like to TIG weld them with Castolin Eutectic TigTectic 224
Tig filler rod. Go on-line and read the description. I would also pre heat the manifold
according to directions, and also bolt it to a scrap head to keep the bolting face flat.
TigTectic® 224
View attachment 854066
Get a Quote

A High-nickel rod for repairing, joining, and building-up of cast iron
Joining and cladding various cast irons such as ductile, nodular, & SG with excellent machinability


Applications
Pump valve seats, engine blocks with surface defects, re-patching large-size holes involving steel-to-cast iron welding, cylinder head cracks between inlet and exhaust ports, touch-up repairs.
Good info, just for fun I want to do an engine block that has been windowed, I’ll be cutting pieces out of a doner block. Big question will this rods-process work for me?
 
Sure will! I had a buddy that bought a used boat up here in Illinois.
It was an Inboard/Outboard Mercruiser four cylinder. He found out that
the one side of the block had been pushed out from frozen water left in
the engine. It opened up the whole top of the water jacket just below
the deck bolting surface. Freeze plugs were still intact! I V'd out both
edges and beat everything back with a dead-blow to where it all looked
good. Welded it up with 224 and that was it! So far I've fixed three more
IO's the same way. The owners were told they needed a new engine. Ha!
This stuff really beads up nicely, and is very easy to apply. I'll look for
some photo's and post them.
 
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