BX 1.9i 8V Exhaust Manifold

[Tim Leech]

Needed for the TZI (hope its the same as the GTi) as its got a small crack which is slowly getting bigger (although I still cant see it) and when cold blows quite badly, as it warms up and expands it gets quieter but you can still here it.

The thought of removing it fills me with fear of snapped studs and rusted solid nuts but ive put it off for 2 years, driving it over to the new house yesterday reminded me to sort it as shes is otherwise a gorgeous beast.

[adamskibx]

Are you sure it's not the gasket, or can you feel the air escape from somewhere other than the gasket? You could try dousing it in WD40 when cold and starting the engine to see where it bubbles. The bolts should be OK to remove, just be gentle and guess the point at which they are likely to shear, then stop. If it is the manifold, welding might be possible?

[mds141]

The manifold on the valver was cracked when I first bought it Tim. I had it welded in situ at Dave Ashworth's back in 2011 and it's still fine now.

[Mike E (uk)]

The manifold on the 16V is made of pipes, the other engines have a cast manifold which I doubt you can weld easily.

Mark, if yours cracked where it was accessible, you were lucky.

I had a crack in mine on the GTi, and replaced it with a used one from a breaker. I had the head off at the time which made the job easy.

Use lots of penetrating oil when you remove the nuts, plus gas is handy here.
IIRC the nuts are copper which helps. Sometimes the studs come out with the nuts, but I have just refitted them like bolts with no problem.

The same manifold is used on lots of PSA engines, so should be possible to find one.

[Way2go]

The manifold on the 16V is made of pipes, the other engines have a cast manifold which I doubt you can weld easily.

Agree with difficulty welding cast iron. Years ago I've had successful repairs on this material by brazing, but for this technique to be successful the manifold would need to be removed from the car. However if you have to remove it from the car then better to replace it with one from a scrapper should one be available.

[citronut]

people wrongly tend to mig weld cracks in case iron manifolds,

i had to sort a Saab that previous people had mig welded several cracks in the manifold,
these cracks kept re/cracking,

till i removed the manifold and took it to a ca restoration company local to me,
they ground all the runs of mig away, then gas welded it all with cast iron welding rods,

it never cracked open again

regards malcolm

[Tim Leech]

Thanks chaps.

[frankguzzi]

If you can get to the crack you can use an arc welder and cast iron rods, if you could grind or gouge a grove into the crack you will get better penetration for the weld, also if you can drill a small hole at each end of the crack you will stop the crack spreading when you weld it. obviously you will weld the holes up as part of the total weld.

[citronut]

gouge a grove into the crack you will get better penetration

oooh la la missus

is it proper to use crack and penetration in the same sentence,

[Tim Leech]

gouge a grove into the crack you will get better penetration

oooh la la missus

is it proper to use crack and penetration in the same sentence,

malcolm, you are a dirty old man!

[Thread Bear]

If you can get to the crack you can use an arc welder and cast iron rods, if you could grind or gouge a grove into the crack you will get better penetration for the weld, also if you can drill a small hole at each end of the crack you will stop the crack spreading when you weld it. obviously you will weld the holes up as part of the total weld.

Flakey used to heat the whole casting up saying that you got a better take on the weld. It makes sense to my rudimentary physics. He repaired a well known Formula Ford engine that threw a rod. They guy believed it was a special block. That unit is still around racing with its welded patch on it, I believe.

[citronut]

gouge a grove into the crack you will get better penetration

oooh la la missus

is it proper to use crack and penetration in the same sentence,

malcolm, you are a dirty old man!

im allowed to be Tim since i reached bus pass maturity

regards malcolm

[citronut]

Flakey used to heat the whole casting up saying that you got a better take on the weld.

this is the correct process,

and apparently if using this method you must not let a giraffe whoooops i mean a draft across the work till its cooled down, as it can crack (darn theres that c word again ) Mr Leach ,
twice in one day what is the world coming to

regards malcolm

[citsncycles]

Another thing you can do (if it's accessible) is hammer the weld as it cools as this helps relieve the stress that builds up and leads to further cracking, although I've never been that successful with that method.