TR4A exhaust manifold cracked

[mike3md]

A TR4A friend has suffered a crack/split in his cast manifold.

 

 

Is it possible to weld or should he look for a replacement?

 

If anybody has a spare available please PM me.

 

Thanks

 

Mike

[Alec Pringle]

They all crack sooner or later, and an uncracked one is hard to find, expensive, and will crack soon enough !

 

A good welder will be able to fix it - cast iron exhaust manifolds are notoriously difficult to weld, but the TR casting is easier than many . . . . .

 

Cheers

 

Alec

[openroad]

Hi Mike , have sent a PM, I have seen one successfully welded.

Cheers,

Conrad.

[RogerH]

Hi Mike,

as stated all these manifolds will and do crack. If it is not cracked it has not been used.

Why do you want to repair it. Once cracked the stresses are relieved and will crack no further.

The gap (crack) is sealed with carbon.

 

If you want to repair it more thoroughly then consider brazing it.

Brazing will cause no further damage. However a bad weld could ruin it completely

 

Roger.

[Geko]

 

If you want to repair it more thoroughly then consider brazing it.

 

 

I think not, brazing will stick not weld on cast iron.

[RogerH]

Hi Stef,

using one of the better brazing techniques the cast Iron will 'stick' perfectly and cause no cracking to the parent metal.

You can weld cast Iron without cracking but it is a more intricate technique.

Don;t under estimate brazing.

 

Roger

[Lebro]

+1 Brazing Cast iron works well, welding requires special welding rods, careful pre-heating, & slow cooling down

 

Bob.

[littlejim]

Just MIG-welded a cast iron BBQ plate with the normal steel welding wire, reasonably high setting but not the maximum.

But needed a heat sink at the back of the iron, and did small welds joined up with later with more small welds.

 

Had a praccy run on an offcut, with no heat sink at back, and got small expansion/contraction(?) cracks on that piece.

Looks like you need the heat sink. Lebro's advice sounds good.

Edited September 23, 2017 by littlejim

[littlejim]

On the faint chance someone is interested

 

[Alec Pringle]

" I think not, brazing will stick not weld on cast iron."

 

On the contrary, brazed cast can be exceptionally strong, and I've seen it done and the 4A manifold last tens of thousands of miles thereafter.

 

Brazing weld does require very careful metal preparation, but nothing difficult. When I last saw it done the whole manifold was brought up to heat over a barbecue fed by an air supply from a vacuum cleaner output, to achieve the heat necessary and then allow slow cooling.

 

No doubt the internet is full of diy videos ?

 

Cheers

 

Alec

[F1loco]

Time for an upgrade ...

 

Don

[AlanT]

There is a special rod called Silicon-Bronze for cast-iron. You can use this like ordinary brazing or with a TIG welder.

 

Attempting to use iron welding risks leaving regions of chilled high-carbon steel which will crack again.

 

Of all the cast iron bits you might try to repair by welding an exhaust manifold is one of the better bets. It will be free from oil contamination which is often a problem.

 

I'd ask this bloke:

[Kiwifrog]

I think not, brazing will stick not weld on cast iron.

I have braced several cast iron heating boilers which have cracked due to being frozen because the heating was left off in a holiday home it is a bit of a pain but as long as you clean back the crack and get enough heat gently into the piece it works and is permanent. It would be easier with a manafold as you can pre heat it in an oven.

 

Cheers

 

Alan

[Kiwifrog]

Ment brazed but overhelpful/frigging annoying apple device changes the spelling of everything and then will not let me edit my post. I wish I knew how to turn it off, you should see what it does when I write French

 

Cheers

 

Alan