Rolls Royce Manifold Repair....

[yorkiepap]

Hey guys,
Attached are pics of the 2nd Rolls Royce exhaust manifold I repaired using the "Cold Welding Cast Iron With MIG" process I have used with complete success.

This manifold was cracked thru the inside flange & the manifold had a severe warpage. After wire wheeling clean, I beveled each side of the crack & extended a bit past the end of the crack. The weld parameters were: .030/309L wire(.01carbon content), 98/2(AR/CO2) @ 18cfh, 90-100A. I tacked each end of the crack & peaned to start. Then I ran a 1/2" bead(pull not push), peaning immediately after welding to relieve the weld. The casting got only warm to the touch & this is the secret to eliminating the dreaded "tinkle". After 15 min. or so back to room temp., I did the 2nd weld on the opposite side, peaning again. I repeated the process till the entire crack was filled nicely.

When I was finished, I took the manifold to the automotive machine shop that does all the machining on the race engines my brother builds. Their work is superb & they have a very extensive machining operation. They surface ground the manifold back to true flatness.

Here's the pics....(9).... gonna need (2) posts to get them on, so give me a couple xtra minutes. Thanks....

Denny

[yorkiepap]

Here's the 2nd group:

[Aerometalworker]

Interesting repair,
Must be just the pictures, but I swear it looks cracked at the toe of the weld in places. I guess the proof will be in how well it holds up over the next years. I have personally never seen much luck with arc welding cast iron, I guess others have though. Seems I always had better luck torch welding castings, let us know how it holds up!
-Aaron

[davinci2010]

I've never migged cast iron, but I've had good luck stick welding it. I use Ni-55 or Ni-99 depending on the situation. You have the right idea; You either weld it cold or weld it hot. No changing horses in mid stream. I have welded it both ways and still prefer a pre and post heat especially on smaller pieces.

[seattle smitty]

You sure better not be in any hurry with this work, especially with the no-preheat method using Ni-Rod (SMAW), which was the way I was taught: run 1/4" of bead at a time and GO AWAY until it's cool enough to hold your hand against it. My first project was the exhaust manifold for my '66 Econoline. That repair lasted at least 25 years, and never leaked . . . despite the fact that the weld bead gradually pealed itself away at the edges, eventually looking like I had laid a length of cast iron clothesline in the bottom of a V-groove! Anyway, having become pretty confident about this system, I showed another guy how it was done, but I got in a little too much of a hurry, and generated some new cracks, very embarrassing!

I've got some new rod from All-State that is suppposed to be used with a 600F preheat (which always did seem to me to be the way to minimize welding stresses), but have not tried it.

While old exhaust manifolds with a lot of miles on them probably have had some of the as-cast locked-in stresses relieved by the years of vibration and thermo-cycling, I wonder if the metal hasn't had some of its mechanical properties "burned out" . . . ??

[Aerometalworker]

You sure better not be in any hurry with this work, especially with the no-preheat method using Ni-Rod (SMAW), which was the way I was taught: run 1/4" of bead at a time and GO AWAY until it's cool enough to hold your hand against it. My first project was the exhaust manifold for my '66 Econoline. That repair lasted at least 25 years, and never leaked . . . despite the fact that the weld bead gradually pealed itself away at the edges, eventually looking like I had laid a length of cast iron clothesline in the bottom of a V-groove! Anyway, having become pretty confident about this system, I showed another guy how it was done, but I got in a little too much of a hurry, and generated some new cracks, very embarrassing!

I've got some new rod from All-State that is suppposed to be used with a 600F preheat (which always did seem to me to be the way to minimize welding stresses), but have not tried it.

While old exhaust manifolds with a lot of miles on them probably have had some of the as-cast locked-in stresses relieved by the years of vibration and thermo-cycling, I wonder if the metal hasn't had some of its mechanical properties "burned out" . . . ??

Well it does atually lose carbon over the years, especially exhaust parts it seems. Another thing to remember is that along with age, casting material has changed over the years. So when someone has trouble working on a 1918 Mekur exhaust manifold, is it age, or material? I rarely work on anything less than 50 years old, so I guess im used to dealing with older materials, and age in general. That being said my experience with electric weld failures is also on that age of parts. By far I have the best luck with O/A welding of castings, yes its a bit slower, and hot work, but the result is beautiful. The welds really dont have a bead shape, they really just disappear, and the weld and base metal is so soft when done a file cuts it like butter. I have done everything from exhaust manifild cracks, to building up replacement cooling fins on a 1908 harley with the process, and done right a repair is undetetable as its just cast iron, base and filler.

[seattle smitty]

Right, gas welding is better. More fun, too, because so many people are surprised that you can do it that way, and even more that it is still the best way.

[jrscgsr]

Still end up with expansion and contraction of the cast material. It expands when heated and is held from moving by the rest of the cast iron around the welded area and has no where to go so it thickens the material and than cools and contracts which pulls on the welded area and then you get cracks. The only way to fix a crack in the middle of a cast iron part is to drill and pin it.

[Aerometalworker]

Still end up with expansion and contraction of the cast material. It expands when heated and is held from moving by the rest of the cast iron around the welded area and has no where to go so it thickens the material and than cools and contracts which pulls on the welded area and then you get cracks. The only way to fix a crack in the middle of a cast iron part is to drill and pin it.

Yes, which is why its pre-heated. Expand as one, shrink as one. As for pinning being the only method, nope. Plenty of production castings are welded, in production.

[Awestech]

I don't understand why some people insist that cast iron can't be welded without it cracking.
I can't count the number of cracked engine blocks, cylinder heads, intake manifolds, exhaust manifolds, etc. i've welded over the last 25 years and not one of them has recracked or leaked.
So it's either not as tricky as some would like you to believe or I am the luckiest man on the planet.

[1930case]

Look at some of the welding and railway shop maintenance books in the Prelinger archive. (They are long out of copyright and free to download.)

They routinely gas welded massive castings for locomotives which were subject to plenty of hard use in service. Repair of severely damaged automobile engine parts was often the only way to get the job done.

http://www.archive.org/search.php?qu...iatype%3Atexts

[yorkiepap]

Hey case,
Thanks for the link, I bookmarked it. Some great information.....

Denny

[jdustu]

I haven't done much cast iron, but appreciate the info. Subscribed for use at a later time

[seattle smitty]

Got a question, Pap. Maybe I was misled a long time ago, but I thought the way to handle that crack would have been (after grooving it out) to stop-drill the ends of the cracks, and then make the short welds starting from the stop-drilled ends, not from the open end of the crack as you did (if I am seeing the pictures right). What is your thinking on the direction of crack-welding?