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Welding a cast Iron engine Block

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#21 ·
trapperjohn said:
Hi DR. I checked out your "how 'dat happen" and I gota tell you the top of that piston looks like something came in contact with it at the edge where the land is broke. I see a straight line across the carbon print and a half moon shape that apperas to be smashed down. For that ring to be captured something had to compress that land. I know you said the combustion camber was fine, but it looks like something was in there.
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I was just looking at that myself. I used to work in tech support for one of the major mail order performance parts companies and crew chief for an American V8 Supercar Series team and while I'm not an expert, I've seen a few failures and had a few thoughts.

Typically a rod fails during the exhaust stroke when there's less resistance to the piston moving up the bore (it's not fighting the compression stroke). Usually the failure is at the point of the "toss" (as it's often called) when the rod starts back down the bore and has to reverse the direction of the piston and "yank" it back down the bore. That's when the rod often comes apart. If that's when this one failed, I suspect the piston hit the head. That would explain the smashed compression rings (I had an engine do this same thing years ago). Is there a matching shiny spot on the head where the piston may have come in contact with the head surface?
 
#22 ·
Do you have access to a TIG machine? If so, you might try to TIG the patch in with some silicon bronze filler. I read about it on weldingtipsandtricks.com, tried it out on a broken cast iron waterpump from my parent's retirement shanty, and it works like a hot damn! Preheat and stress relief rules still apply, of course. Just a suggestion! I'm interested to see how the repair turns out regardless of the route you take. Good luck!
 
Discussion starter · #23 ·
trackbird said:
Typically a rod fails during the exhaust stroke when there's less resistance to the piston moving up the bore (it's not fighting the compression stroke). Usually the failure is at the point of the "toss" (as it's often called) when the rod starts back down the bore and has to reverse the direction of the piston and "yank" it back down the bore. That's when the rod often comes apart. If that's when this one failed, I suspect the piston hit the head. That would explain the smashed compression rings (I had an engine do this same thing years ago). Is there a matching shiny spot on the head where the piston may have come in contact with the head surface?
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Yes, likely when the rod finally broke the piston was slung to the top of the bore and contacted an open valve. Most likely the intake because it is a 2" valve. The intake valve itself seats cleanly but that is no proof it isn't bent. Have to remove it from the head to ascertain that.
From the research I have done the powdered metal rods fatigue and then bend before they break. Looking at the wrist pin end of the rod you can clearly see it is bent to one side.
There has been a lot of rod failure in trucks in the '03 and '04 models. You need move beef in connecting rods for heavy truck applications. These failures do not happen in the car applications.
 
#25 · (Edited)
I was always taught to preheat when welding cast iron. Am i wrong? I have done several cast iron repairs and always preheated first. I used to have a set of "melt sticks" that would melt at certain temperatures. If i remember right cast was recommended preheated to 1000 ?? Grind a bevel into all surfaces to be welded. Weld and post heat. Then slowly cooled, submerged in sand to keep from cracking.
Every repair i have done has worked and held as far as i know.
Might look into this.
I found this link that was interesting. http://www.locknstitch.com/PreheatWeld.htm
Moose13
 
#26 ·
ed mac said:
castweld have you ever used ni 44 (tig)
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Yes I have used this, all of the nickel iron rods will work. The rods with higher nickel leave a softer weld, ni99 leaves softest weld but haz is extremely hard. The 44 nickel iron rods have manganese that give a softer haz but the weld is harder than the ni55 which is why I currently stock the ni55 (softer weld) and ni99. Some of the lower ni rods will color match cast iron, are magnetic, and will rust. But some are non machinable.
Peter
 
#27 ·
moose13 said:
I was always taught to preheat when welding cast iron. Am i wrong? I have done several cast iron repairs and always preheated first. I used to have a set of "melt sticks" that would melt at certain temperatures. If i remember right cast was recommended preheated to 1000 ?? Grind a bevel into all surfaces to be welded. Weld and post heat. Then slowly cooled, submerged in sand to keep from cracking.
Every repair i have done has worked and held as far as i know.
Might look into this.
I found this link that was interesting. http://www.locknstitch.com/PreheatWeld.htm
Moose13
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Heating is an accepted method, so is cold welding. I would rather heat in the 1100 degree range but in this case the block would have to be remachined on most surfaces (expensive). Although cold welding is not "best" method it will cause less high heat related problems. It does work, I repair many castings both ways.
Peter
 
#28 ·
castweld said:
Heating is an accepted method, so is cold welding. I would rather heat in the 1100 degree range but in this case the block would have to be remachined on most surfaces (expensive). Although cold welding is not "best" method it will cause less high heat related problems. It does work, I repair many castings both ways.
Peter
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Hi cast weld
desribe cold welding cast- what temp range are you referring to?

that was my first try on cast welding the other day so i looked it up. it said to keep the metal out of the 150F to 499F range and not go over 1200F-1400F because it causes brittleness.
I kept it in the 500F+ range is that what your referring to?
 
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#29 ·
galencwi said:
Hi cast weld
desribe cold welding cast- what temp range are you referring to?

that was my first try on cast welding the other day so i looked it up. it said to keep the metal out of the 150F to 499F range and not go over 1200F-1400F because it causes brittleness.
I kept it in the 500F+ range is that what your referring to?
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Cold as in do not make another weld untill you can hold hand comfortably on last weld-under 150F.
Peter
 
#30 ·
thank you.
 
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#31 ·
After welding the block, the crankshaft and cam bearing bores should be align bored to compensate for any distortion (warpage) created by the localized heat of the welding.
 
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Discussion starter · #32 ·
Don't know if considering the operating temp of an engine block which is usually around your coolant temp180*-220*. The oil splashing of the crank case has some cooling effect and the block itself is kept in check by the coolant system. This is nowhere near the "hot spots" would would be near the upper cylinder walls.
 
#34 · (Edited)
Dr. Righteous said:
So a Cold Weld is not preheating the area to be welded at all?
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Yes, Peter is still green now, but he may be like I sometimes do... sleeping with a laptop....

I used to explain to folks "place your bare non welding hand or finger about 1" from the weld and when you can't keep it there you're done for now". That's over 140 degrees F.

Everyone welding cast has habits that make them feel comfortable about the weld, and all seem to be a bit different. But Cold is cold, and hot is hot... Then all the goofy habits the weldor has happens, no matter, cold is 140-150, hot is 1000 or 450 and gaining heat to red.

The real latitude comes from looking at the block, yours has a lot of material from the area with the boo-boo to areas that do more than hold oil. Cast moves and adjusts too.

Matt
 
#35 ·
My preferred method of cold welding, which I use for all large castings it to preheat as much of the casting as possible, and as evenly as possible, but not more than300 - 400 deg.F. If you sand down some surface area around the break, you can keep an eye on it while preheating to see that you don't cause discoloration. Then I set and tack the patch or missing pieces. Once I am all setup, If I can hold my bare hand on it, then I start with a short stitch, and keep myselfbusy by peening it with a sharp pointed chipping hammer until it is cool enough to touch bare handed again. If I am forced to leave for even a short period, a cover it with a fire blanket or leather jacket. If it cools off to the point of being back to room temperature, then I start over with the heater, but if at all possible, don't stop untill the repair is complete. If it feels like when you wrap your hand around a mug of hot coffee, then it should be ok.
 
#37 ·
I have repaired many 427...428 "Windowed" Ford blocks but we always took them apart and pre heated the block in a homemade oven with 300 lbs of charcoal going to get it red hot..
Repair the area and then return to oven and let cool naturally..
This took 3 days but they always held..

...zap!
 
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#39 ·
Gives a whole new meaning to "Blown Hemi" :laugh::laugh:

...zap!
 
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#40 ·
I have a bad one i am trying to repair. I dont know if i am going to be able to do it though, it brought at one of the cross bolts... And the pan rail area also has a chunk taken out of it...
Image



what do you guys think
 
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Dr. Righteous
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