consequences of using cracked exhaust manifold?

[Tex Terry, II]

Derek - I have used JB Weld on a couple of cracked manifolds in the past
with good results.  First make sure the pipe is cold (has not had the
engine run for at least 24 hours). Then wire brush the area of the crack to
clean away any loose scale.  Mix the JB Weld as per the instructions on the
two-tube package and apply.  This should be a temporay fix, but I have
personally know of a case that the weld lasted for three years until the
vehicle was sold by my friend.  
Tex 
83 5kt
> 
> Message: 7
> Date: Mon, 25 Jun 2001 09:15:29 +0200
> From: Gerard <gerard at poboxes.com>
> To: Derek <quattro at telocity.com>
> CC: quattro at audifans.com
> Subject: Re: consequences of using cracked exhaust manifold?
> 
> Hi!
> 
> Mine ticked as well. Very, very loud. Eventually it just ticks all the
> time. If it's anything like mine then warm-up will not cure the ticking.
> Mine sounded like bad lifters all the time. I don't know about long term
> consequences, but I can say once the cracks are going all the time it
> sure does lead to a filthy engine bay. Or so it seems.
> 
> I have no idea about performance losses.
> 
> As for the cracks, the can definitely be repaired by welding and I think
> the idea is to have it done properly and the metal built up around the
> crack. That's what they did to my manifold which I hope will last a
> while when it goes back on the car. The old 1-piece that came off the
> car had a weld on the crack, but it was just on the crack. The crack
> happened again right through the weld.
> 
> Almost all the used manifolds will have cracks at the turbo end, even
> the 2-piece units.
> 
> G.