Iron Block Casting Repair with Weld Mold 700/750 TIG Filler
See this Caterpillar engine block repair, using TIG (GTAW) welding process and Weld
Mold Company 700 and 750 filler rod. The bare block fix, performed on the shop floor
at Brad Falin's heavy equipment repair facility, took two hours and saved thousands
of dollars. Iron engine, transmission and axle housings can be restored.
Brad Falin is a Cat master mechanic and runs a heavy equipment repair
and rental facility. When Brad is not swamped with heavy equipment work, his 4x4 race program
gets attention. (Brad ran the first
diesel-powered Ultra4 4x4 at the 2012 King of the Hammers
and has been a VORRA
champion.) At right, Dee Wade is about to fill the hole punched through the side of this Cat engine
block. The repair will save time, materials and the cost of a new bare block.
The broken casting piece gets shaped and beveled for TIG welding into place.
Fortunately, the broken section of the block is not a water jacket or crankshaft web support area.
This will be a repair with a positive, permanent outcome. The Weld Mold
Company 700 and 750 filler materials prove compatible with the iron block. Weld Mold 750 can
boost tensile to 75,000 PSI in the welds.
Dee Wade performs the TIG welding repair. He begins by thoroughly removing all
paint, debris and contaminants. TIG requires clean iron. There is a shielding gas of 100% argon in this case,
and the primary filler rod is Weld Mold Company 750, which offers a mix of graphite forming iron and
nickel. The filler is a match for the Cat engine block casting, and welds lay down smoothly and quickly.
Dee uses a foot pedal for voltage control and sets his inverter TIG to its maximum
output of 200 amps for a 3/32" electrode and 0.062" filler rod. He controls the application of heat to
produce deep penetration TIG welds. With its concentrated heat, TIG makes a superior weld and reduces
the overall heat affected zone (HAZ). Cast iron is notorious for cracking as the weld cools and shrinks. Weld
Mold Company fillers help to eliminate the risk of cracking at the edge of the weld area or HAZ.
The initial welds and tie-down passes also repair the stretched and stressed
areas of the original block casting. Note that the block did "stretch" and bend slightly, an indication that
this is a more ductile iron than simple "gray casting". To minimize risk of stress cracking, Dee uses a propane
torch to heat the block in the repair area and surrounding casting before continuing his weld repair. Use
a surface thermometer to check on the casting temperature, which can swing widely over a large mass
The finished repair shows strength and a complete seal. (Brad emphasized
that permanent bonding epoxy can be applied inside the block as insurance, though it is doubtful that
this block would have porosity after Dee's painstaking TIG welding.) Any concern would be oil
wicking, as there is no coolant passage involved. Weld Mold Company 700 and 750 filler material assures a
permanent fix for this Cat engine block. After the last weld pass, Dee heats the entire casting to a
uniform 250-280 degrees Fahrenheit before covering the block with a heat blanket and allowing it
to cool slowly and uniformly.
A TIG welding example from the magazine's own shop, this rare vintage
power steering gear housing is repaired with TIG process and Weld Mold Company 700 and 750
filler rods. Care given to the amount of pure nickel (700) applied can actually increase tensile
in a weak casting. The gray iron housing shown has been notorious for cracking. At right, a steel
reinforcement strip is welded inboard of the weak area, using Weld Mold 750 filler rod. For more
details and a slideshow on repairing another large iron casting, click here!
At left is the steering gear casting repair with Weld Mold 700 filler rod, note the nickel
content in the weld coloration. The casting is gray iron, so Weld Mold 700 (pure nickel) works well with
the anticipated dilution from the near pure iron casting. At right and below is a thorough casting ear
reconstruction done at the magazine's shop/studio to restore a T86E iron transmission tailhousing. Both Weld Mold
700 and 750 are optimal for these kinds of repairs, neither filler requires elaborate pre-heating or
preparation beyond a thorough cleaning of the casting before TIG welding. Click here for a PDF with details on Weld Mold 700 and 750 filler rod details and
While TIG is the process shown in these repairs, Weld Mold Company 700 and
750 rod is available for other welding methods as well. Weld Mold Company offers a full line of highly
specialized, niche welding materials and alloys for industrial use and our automotive needs. To see
the broad range of products available and learn more about Weld Mold Company products: Click here to visit the official Weld Mold Company