How-to: Iron Engine Block Casting TIG Weld Repair

HTP America Welding

Professional Iron Block Casting Repair with Weld Mold 700/750 TIG Filler Rod!

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 Fernley, Nevada heavy equipment repair facility, took two hours and saved thousands of dollars. Iron engine, transmission and axle housings can be restored…

Brad Falin's shop and race program
Caterpillar block with hole punched through wall

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 4×4 race program gets attention. (Brad ran the first diesel-powered Ultra4 4×4 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.

Broken block piece used for bridge in weld
Heating block web below area of repair

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.

TIG welding process for cast iron repair
Weld Mold Company 750 TIG welding filler rod

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.

Striking arc and gas shielding with argon
Using a descaler for shot peening after weld pass

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.

Initial patch tie-down with welding tacks
Dee Wade brings casting temperature up for welding

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 like this.

Penetrating welds and successive passes to finish buildup
Structurally sound and permanent repair with TIG process

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.

Moses Ludel Uses Weld Mold Company’s Filler Materials for Vintage Jeep and Automotive Cast Iron Repairs!

Another iron repair with Weld Mold Company filler Weld Mold 700 and 750 filler rod and TIG process

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!

TIG process optimal for cast iron casting repairs
Broken T86E transmission casting

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 applications.

T86E with Weld Mold 700 and 750 casting repair
T86E casting repaired
Shaped after Weld Mold TIG repair
Painted and as new casting!
Weld Mold Company 750 Cast Iron Repair Filler
Weld Mold Company

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 website!