Exhaust manifold: broken

Durango2k · Post by **Durango2k** » Thu May 12, 2016 9:09 pm

Hi guys,

I had a closer look at my exhaust manifolds, and one of them has 2 ruptures: where the 4 lower large bolts are fitted, there is one rupture per hole.

What would you do ? It's rather thin metal, I am not sure if this will last, furthermore the holes with ruptures are the outer two, they're neighbours.

Should I weld it on my own ? Have it welded (not cheap because its cast iron) ? A new one is 200 E from SNG, plus it is shiny new and my second one is good, but old and rough.

Or simply fit the 4 stainless bolts I have here and fit to car ?

Or weld a bent nail around the outer edge ?

Carsten

cactusman · Post by **cactusman** » Thu May 12, 2016 9:21 pm

Welding cast iron is notoriously hit and miss. Leave to an expert. Old ones do crop up on well known audit n sites from time to time.

christopher storey · Post by **christopher storey** » Thu May 12, 2016 9:22 pm

Trying to repair broken cast manifolds is frankly a waste of time . At best, any welding will be a temporary repair. Equally, replacing them with modern ceramic coated reproductions is a waste of both time and money because the first time water gets on a hot manifold the ceramic will start to craze. You can buy new uncoated ones quite cheaply which when painted regularly with barbecue paint or other High temperature paint will produce an easily maintained and quite good looking manifold

Durango2k · Post by **Durango2k** » Thu May 12, 2016 9:26 pm

...where can I get new unpainted / uncoated ones ?

I mean it's only the thread surround, and the bolt still grips. The rupture is not open.

Methinks to grind a V, and try to weld it with my MIG.

Hey, I just invested money in them to have them flattened !

In the end, if it does not last, it is not too difficult to change, and not safety relevant.

Carsten

christopher storey · Post by **christopher storey** » Thu May 12, 2016 9:34 pm

I believe that Hutsons sell them - a recent thread mentioned this. If you are happy with the present structure , then I would keep them. It is only the work of an hour or so to change them later

abowie · Post by **abowie** » Thu May 12, 2016 9:46 pm

Durango2k wrote:Hi guys,

I had a closer look at my exhaust manifolds, and one of them has 2 ruptures: where the 4 lower large bolts are fitted, there is one rupture per hole.

What would you do ? It's rather thin metal, I am not sure if this will last, furthermore the holes with ruptures are the outer two, they're neighbours.

Should I weld it on my own ? Have it welded (not cheap because its cast iron) ? A new one is 200 E from SNG, plus it is shiny new and my second one is good, but old and rough.

Or simply fit the 4 stainless bolts I have here and fit to car ?

Or weld a bent nail around the outer edge ?

Carsten

I've spent a lot of time welding and trying to repair these manifolds.

It doesn't work.

Buy new ones.

Moeregaard · Post by **Moeregaard** » Thu May 12, 2016 9:47 pm

One of the cast manifolds on my old '65 FHC had a crack from one hole of the downpipe flange and it never gave me any trouble over 16 years of ownership. If the stud remains tight I would just live with it.

PeterCrespin · Post by **PeterCrespin** » Fri May 13, 2016 2:05 am

Durango2k wrote:...Hey, I just invested money in them to have them flattened !

No comment.

Even if you wanted to weld them, a MIG is the wrong tool.

Durango2k · Post by **Durango2k** » Fri May 13, 2016 5:21 am

Of course I know. You need an electrode welder and electrodes to match the iron type of the manifolds.

But if all what you have is a hammer then every problem becomes a nail :-).

Seriously, I think the place to weld on is small, the work to do it properly is costly, so the best option is to really buy new.

But - if I have to buy new anyway I can also simply drool around with my MIG...this item is dead as a dead cat anyway.

Carsten

MarekH · Post by **MarekH** » Fri May 13, 2016 6:40 am

I don't think any amateur welder will be able to put enough heat into it to make anything stick. Go to a blacksmith. Get him to heat it up to red hot and then melt some brass into the crack around the bolt hole where the "ear" was overtighhtened onto a non-flat surface.

When cool, file it back.

kind regards
Marek

vrracing · Post by **vrracing** » Fri May 13, 2016 3:08 pm

I'd give it a try just for fun. If it doesnt work the worse thing you lose is an exhaust manifold gasket and some mig wire. ChuckE2009 has several videos on Migging cast iron here. There are others on YouTube if you search.

IIRC, to have a chance you need to heat the piece for many hours to out gas any oils (cast iron is porous and Jaguar's chassis rust prevention system ensures you'll have oil in the manifold). You have to grind out the crack to a groove. You have to heat the whole part up again then wrap it in a welding blanket, do the weld with lots of heat (and the right wire) and then either keep it wrapped in the blanket or put it back on the grill and over many hours slowly bring the heat down.

Better built than bought! And don't burn yourself!

Jim

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