Cracked manifold, worth fixing?

arrabil · Aug 13, 2007

I bought an exhaust manifold for my neighbor to replace the one his kid cracked, then his kid proceeded to crack that one. I don't remember having this much trouble with curbs at high speed when I was learning to drive... but anyway... this crack is pretty small as opposed to a complete shear like the first time.

Can the crack be filled/repaired?

Or should I just have them find another junkyard manifold?

My neighbor has every conceivable metal working tool in his shop if that somehow helps.

Thanks!

Capt Jay · Aug 13, 2007

Get different ones. You can't weld pot metal.

gw33gp · Aug 14, 2007

Capt Jay said:
Get different ones. You can't weld pot metal.

I am very sure the exhaust manifolds are not pot metal. Typically they are cast iron. I have seen brazed cast iron manifolds hold up on farm equipment but I don't know if it would work on a Ranger.

Brazing would most likely cause distortion and that would require machining the sealing surface flat to keep the exhaust from leaking. Probably better to get another one.

baddis · Aug 14, 2007

if you bolt the mounting flange down you can arc weld cast .bolt it flat so the mountig flange doesn't warp. welding cast takes alot of heat . so it might be more cost effective to just replace the manifold

arrabil · Aug 14, 2007

What about some kind of exhaust filler material I've seen at the auto parts store? I used some in another vehicle but it wasn't to fill a manifold crack.

What the hell is pot metal?

Explorin94 · Aug 14, 2007

You can actually weld that manifold like Baddis and GW33GP said but you have to get the metal to where it is almost flowing before you can strike and arc. I have done it but have used and old cracked head because of the heat involved. Once it was welded I left the manifold bolted to the head until it cooled down. May be worth just finding another one and have the kid put it on and see if he thinks it is easy for you to keep doing it.

arrabil · Aug 14, 2007

Well, that I'll give the kid. I made him do all the work while I stood there drinking Natty Light. He got the rivets off to remove the coil bucket on both sides (first time both manifolds were SHEARED). He snapped all the manifold bolts himself. His dad made him watch while he drilled out the heads. I made him reassemble everything and sent him to the store for all the parts. That was after we already had the axle out to replace the radius arm bracket he bent.

Then he Britney Spearsed it... ooops I did it again.

85_Ranger4x4 · Aug 14, 2007

arrabil said:
What the hell is pot metal?

Cheap metal, it is usually high in zinc. You can't weld the stuff, and it wouldn't be a good material for an exhaust manifold.

http://en.wikipedia.org/wiki/Pot_metal

v-8power · Aug 15, 2007

It can be welded but it will require a lot of prep.

First you need to drill a SMALL hole at each end of the crack. Then heat the manifold up
and peen the crack. Then wire brush the area to be welded. Take your electrodes for welding cast and do it up. If you do it right it will not fail. Good Luck

85_Ranger4x4 · Aug 15, 2007

v-8power said:
It can be welded but it will require a lot of prep.

First you need to drill a SMALL hole at each end of the crack. Then heat the manifold up
and peen the crack. Then wire brush the area to be welded. Take your electrodes for welding cast and do it up. If you do it right it will not fail. Good Luck

You can weld cast but if the kid keeps hitting curbs it may make the area weaker to be broken again.

MAKG · Aug 15, 2007

If this is an older vehicle, get a good manifold from the junkyard. It's not very expensive and a dang sight less work.

arrabil · Aug 15, 2007

We have the two most brilliant junkyards near us [same owner]...

-How much for this taillight?
-Seventy-five bucks.
-How much for this bumper piece?
-Seventy-five bucks.
-How much for the seats?
-Seventy-five bucks.
-How much for the exhaust manifolds?
-Seventy-five bucks.
-What doesn't cost seventy-five buck?
-The engine and transmission.
-Half these things cost less than $50 new.
-Then what are you doing here?

So I'd have to mail-order a manifold from someone or car-part.com.

What about this stuff:
Exhaust manifold repair kit
Says its good to 2000 degrees.

arrabil · Aug 16, 2007

No one knows anything about this stuff or something similar? Exhaust manifold repair kit

MAKG · Aug 16, 2007

It's a steel-impregnated epoxy, right?

I'd be quite concerned about thermal expansion. Exhaust manifolds expand substantially between cold and highway-speed. At a minimum, you'll need to "stop" cracks like you do on windshields (drill a small hole at both ends), and clean the surfaces carefully. And I think it will still re-crack.

Isn't there a less problematic junkyard around? That really is the best solution....

arrabil · Aug 16, 2007

I don't know about the steel impregnation and I don't know of any other junkyards near me. I could find the Maryland Yellow Pages I guess. I wish one of those places by Allan would open up here!

I will print out this thread and my neighbor can decide for himself. Thats the best course of action.

Thanks again.

Cracked manifold, worth fixing?

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