Repairing Block and Cylinder Head Cracks on the Model T Ford
Our friend owns this beautiful 1910 touring. Its open valve engine has a water leak from the center of the block where the water jacket has rusted through and cracked. If it was a later block with enclosed valves this would cause water in the oil. Since this is an early block, it mostly causes a big mess.
We decided this was a perfect defect to repair with fairly easy methods. Read below to see what we did to repair this common problem.
This type of crack / leak is caused by using plain water, or water mixed with soluble oil, instead of anti freeze. Anti freeze if a proper mixture of ethylene glycol and water, will prevent corrosion. This engine was run for many years using just water, and drained in the winter time, so that it rusted severely. There are people who can effectively weld cast iron in order to repair this type of damage. The problem is, if you do that, then the block will be distorted and all the Babbitt will be ruined from the heat. We have a less intrusive way to do a repair that will last for years.
We decided to repair the block as follows:
Clean the area with the damage as best we could inside and out, removing paint and corrosion from the area around the repair.
Block off the engine water inlet and outlet so that vacuum could be applied to the inside of the engine.
Apply a two part epoxy to the outside of the damaged area so that the vacuum would draw the sealant into the damage. We used JB Weld. Other product brands are Dexter Hy – Sol and 3M Epoxy Patch.
Apply a sealing tape over the epoxy so that the vacuum could only make the repair flush with the outside of the block. If this step was skipped the vacuum would suck the epoxy in until the hole was open again.
Update: As of April 2019 the repair has been in place five years. Still no leakage after all this time.