Cracked Exhaust manifold

[appletree]

After a annoying tappety noise my car has had for abit i changed all the tappets for a known quiet set but the noise never changed.

This noise wasnt there when the car was cold or when the car was hot only when it had been hot and then you had pulled in to fill up or just nipped in to the shop , when i restarted it i would get a tick tick tick noise like a tappet that was sticking, however if i let the car tick over for abit it would go away and also it was only realy noisey under load not at idle.



Anyway i decided to check if i had any cracks in the one fitted to the car now and this is what i found.

To remove the manifold on the engine is abit of a ball ache made worse by the heat wrap ive put on it as now my whole arms itch like mad! You have to remove the steering linkage to get the manifold out from the bottom which is still abit tight but doable.

Both cylinders 1 and 4 have cracks on the weld right next to the flange, suppose its to be expected when the manifold is at times coping (or not) with over double the horse power it was designed for.

If anyone has an uncracked spare for sale then let me know!!!!!

Just a bit of soot on the out side.



Inside cyl1


Inside cyl 4 - this is the worst one, quite a hole at about 10o'Clock.


One good thing about removing it though is that you can see how well and evenly its running.

[DanThe]

Unlucky, they are well known for cracking though

[appletree]

Ya, i know my old one was cracked to but i didn't get any noise from it or atleast nothing like this one but it was only on cyl1 and not as far round or as wide...

Going to ask one of the welders at work to have a go at TIGing over the crack once ive ground it back and beed blasted it.
Got two chances

[DanThe]

Welding it inside and out is the best way

[appletree]

That's what my dad said too, only issue is the manifold plate is made of sandwiches 2 stainless and 2 mild for some reason and the mild is the bit that you can see with regards welding the outside. Should be ok though with a bit of prep.

[jimmyspeed]

at least there quite easy to see, im building a turbo manifold and every time i need to check for holes i have to clamp it, grease it, and spray with soap! it well annoying

have they used stainless to stop heat going back into the head?

[appletree]

have they used stainless to stop heat going back into the head?

No idea, suppose as the manifold its self is a low grade stainless they used a stainless flange, realy don't get the 4 layers unless its somthing to do with letting it flex abit under expansion? the other end of the exhaust were it goes from 4-2 also has the same layered design and on both ends though only the stainless flanges are welded to the runners them selves and then the stainless flange is spot welded to the mild one...

[jimmyspeed]

suppose as the manifold its self is a low grade stainless - i didnt see the runners were stainless

but that makes it even more odd to run the whole lot through a mild flange

[DanThe]

Stainless pipe and mild steel flanges are common practice with exhausts, just turn the current up