Dryslick13

I have a bad crack on the header that goes to cyl 1 and 4. It is right were the two pipes merge to the collector. What is the best way to repair this so it will hold? Looks like it is cracked under the plate that braces the pipes at the Y. Guess I'll need to cut this off to fully repair the crack? Is there any way to better brace the pipes? I am missing the hanger that goes in front of the cat. I have the parts to put that back in, but need to weld on a flange to the pipe to bolt the hanger to. Tried buying a used set from e-bay but they ended up being cracked just like mine. Hope he gives me a refund since he said they had no cracks!

Strike-Force

If you patch it it will crack again. The only way to get rid of the problem is to replace the manifold.

Wipeout

Agreed - replacing it is the only way. I have the headers from my early '85 (don't recall any leaks/cracks, but I think mine are cast. They should fit an '86, but not sure if you'd want them. Yours for shipping if you need 'em.

m73m95

Wrong..... it can be welded.

It takes special rod..... and its one of the rare cases that arc (stick) welding is the preferred method. Arc welding rod remains flexible, and will expand and contract with the heating/cooling of the manifold.

Take it to a good welding shop for the fix..... or send it to me. I have welded MANY exhaust manifolds on big diesel engines. They crack all the time. Nickel rod is $$$$, but it will never crack in the same location again.

(EDIT .. I read "manifold" as you having the early cars cast iron manifold..... if you have a late car header, that can be repaired as well, just a different process.

Never trust anyone that tells you something can't be welded, and have it be strong. Everything made of metal in the world has been welded at some point, and many times, the weld is stronger than the surrounding metal.)

Tom M'Guinn

How about the heat shields on the 951 manifolds? Any tips for MIG welding those back on after removal?

m73m95

Those are filled with some kind of black beads.... I haven't seen them, but I have read posts about them. They absorb the heat I guess.

If they (heat shields) are whole, just removed, they should just be spot welded back on, then "refilled" with whatever that stuff is.

m73m95

Also ..... never trust anyone that says something can't be welded and be strong. Everything that is metal in the world has been welded at some point... And most times, the weld is stronger than the surrounding metal.

Every kind of metal, and every use for that metal takes a different welding process. Meaning, there are THOUSANDS of ways to weld "correctly".

Just because somebody tried welding a cast iron manifold in their garage with a torch and coat hanger, which of course failed, doesn't mean they know WTF they are talking about.

Some metals require processes that cannot be done in a garage (titanium can only be welded "correctly" in a vacuum). Take your stuff to a good/certified weldor.

kombatrok

Why not replace with MSDS headers? Cheap and easy. Replace the cat with a modern high flow imo while you are at it.

dme

I had Marcus (in Canada) weld my 2-3 header. He added an expansion joint to relieve the stress and keep it from cracking again. He also welded it while installed on a head to keep the alignment correct. The first (local) guy who did it, welded it free standing and it would not fit back on the head.

elzergone

Does that have any noticeable effect on an NA? I was under the impression it was kind of a lost cause. Or are you just suggesting it as a cheap fix.

JimV8

It can be welded without a lot of trouble. I'd gas weld it. Oxy/Acetelene is great for doing that kind of stuff.

Dryslick13

I've got the late headers. Guess I'll take them to a muffler shop since I only have a MIG welder. Have a shop nearby that does good work on the cheap. What are the MSDS headers? Would be interested in them if they are not too much coin.

Dryslick13

Wipeout, I might take those cast manifolds off your hands if the muffler shop can't fix the cracked one I have.

kombatrok

I didn't really notice much difference, but it was a little louder. It's just an inexpensive, well made one piece header.

m73m95

If you were on the other side of the divide, I would suggest a great weldor for you to take your headers too.

You should be fine MIG welding it, as long as you are using gas (not inner shield), and can purge the inside of the headers as well.

If you do take them somewhere, I would not suggest a muffler shop. Take it to a professional weldor.... maybe even a fab or machine shop. The fix should only take 15-30min to do right, so you can probably find someone to do it on their lunch break for a 12 pack