My 3800 II SC exhaust manifold is cracked. It is cast iron which I know is hard to weld, but it is possible. Is it worth trying to fix, and who can I seek out to do this?

Stock manifold like 3800 swap people throw away?

If you lived here I could get it done for you my dad is the best welder I know of he has his own welding truck
and is awesome at welding cast. I know his tecnique how to weld it but, I could never do as good as him.
He has said before that some cast just wont hold a weld and some will.So good luck.

[This message has been edited by v6autogt (edited 01-25-2011).]

Sorry, I threw mine away otherwise I would give you one.

I was told it could be welded, but that it is a process. You have to heat the metal to a certain temp, then use nickel rod, and then there is a cooling process. If it cools too fast it will crack again. So there is a science to it, that a layman such as I, with a simple home depot flux core welder can not even touch!!!!

Morad is selling a mainfold but they want $25 for it, and then an additional $27 to mail it. Sounds ridiculous to spend over $50 for something that can be had for less, or simply welded.

Does Roger Garrison still do welding and porting of manifolds? He did mine, I had them JetCoated, and they've been trouble free since 2002.

I welded a manifold for a guy with my mig and its still holding but on his I was able to put weld on the inside as well.
But I do not call myself a welder because of it but I have helped my dad for the last 20 or so years.
All jobs like that are different the location of the crack is the main concern.

Welding cast iron is very difficult because the thermal stresses of welding normally exceed the brittleness of the metal, resulting in further cracking.

Yes, a long pre-heat and cool-down are required, and the process to use is SMAW (stick) with a special high-nickel welding rod. Afterward you'll need to make sure the flanges are perfectly in plane with each other and flat, otherwise you'll just get more cracking.

Honestly, it's going to cost you more in time and money to a welder to repair this manifold than it will to buy that used one. That's why this kind of repair is typically only used for exotic/rare/antique/expensive parts, none of which the stock 3800 manifold qualifies as.

It's not that complicated in this application. I've been MIG welding on OE cast iron manifolds since 1995 and haven't had a problem yet and they saw extreme heat behind turbos. Just make sure it's mounted to the head just in case there's a chance of warping. Read up on it, heat is only required in certain instances, had to investigate this before tack welding a critical cast iron part recently. I did use stainless wire with a nickel mix but that was because of the application.

I was told years ago by a professional to use flux cored wire but after that I had such good success with regular steel wire I didn't bother to deal with the mess flux-cored wire makes.

Don't get me wrong, what the guys are telling you is important and pretty accurate in general, but in my experience and given the quality of OE cast iron you should be able to have it welded as if it were mild steel and not have a problem. You just can't drill a hole in the welded area as it will be tempered to near impossible to do anything but grind.

Blew a quarter sized hole out of the exhaust manifold on my tractor (old age) and fixed it by brazing on a patch cut from and old header. It's ugly, but has held for the past couple of years. I have also simply mig welded cast iron with great results.

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1986 SE 350 V8

quote Originally posted by Joseph Upson: It's not that complicated in this application. I've been MIG welding on OE cast iron manifolds since 1995 and haven't had a problem yet and they saw extreme heat behind turbos. Just make sure it's mounted to the head just in case there's a chance of warping. Read up on it, heat is only required in certain instances, had to investigate this before tack welding a critical cast iron part recently. I did use stainless wire with a nickel mix but that was because of the application. I was told years ago by a professional to use flux cored wire but after that I had such good success with regular steel wire I didn't bother to deal with the mess flux-cored wire makes. Don't get me wrong, what the guys are telling you is important and pretty accurate in general, but in my experience and given the quality of OE cast iron you should be able to have it welded as if it were mild steel and not have a problem. You just can't drill a hole in the welded area as it will be tempered to near impossible to do anything but grind.

Just a note.... I had to have something welded on the head and the weld shop used a nickel rod. These guys weld all day, so I tend to believe what they say. Now, on the farm, we used to braze manifolds and they held. My brother (who passed away) was a professional welder and he used a MIG to weld the flanges on my manifold. So, yup, it can be done, but there are many ways and it depends on what the item will be exposed to.

I would just get another one...

It's just an exhaust manifold. If it's easier to lay a bead across the crack and go I'd do it and get it over with. The car won't roll over and catch on fire if it doesn't hold.

quote Originally posted by Joseph Upson: The car won't roll over and catch on fire if it doesn't hold.

No, but he is referrring to a firewall side manifold, so I wouldn't completely rule out fire.

quote Originally posted by Jncomutt: No, but he is referrring to a firewall side manifold, so I wouldn't completely rule out fire.

Not a chance with a simple crack in a cast iron manifold. The stock manifolds leak bad enough and if that's not enough they glow red hot even when they're not leaking. He has about as much to worry about with the cast iron leak starting a fire as he does with the stock manifold. Weld that thing and go man.

[This message has been edited by Joseph Upson (edited 01-26-2011).]

My concerns aren't fire. Most states have inspection programs, often annual, that would fail a vehicle with an exhaust leak from a cracked manifold. Also, there's a remote but not zero chance that air can be sucked into the manifold through the crack in sufficient volume that it's oxygen will throw off the ECM by altering the O2 sensor reading, making it think it's lean when it's really not. As far as the repair itself goes, the labor for the repair is the real hassle. The risk of having to redo the manifold twice isn't worth the $50-60 it will take to put a good one in instead.

I don't know if it's been mentioned because I'm not reading all that above. Working in a machine/weld fab shop we did work on cast iron manifolds with cracks. Rarely did we weld them. Most commonly we brazed them, so you might look into that before trying to weld.

[This message has been edited by Khw (edited 01-26-2011).]

Everyone here realizes we're talking about the same manifold that's on every '96-'08 fwd 3800 in world right...? Not only that, but being the front manifold in "land yacht" engine compartments, it's a walk in the park to get to and remove. I replaced a manifold with a hole in it the size of a dime (at the base of the middle bank). Jnco's cracked entirely in half (forgive me John for offering up this). The cast iron manifolds don't stand up to the added heat of the supercharger very well. Why would anyone want to "repair" one of these things?

It cost all of $20, to pop another, better condition, manifold off.

I have a few laying around I think, probably in scrap pile. How about getting a ZZP Plog instead? A little better knock resistance, two birds with one stone.

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Turbo 3800 E85 5spd spec5
11.53@126.7

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