New radiator leaking

[tom yuenkel]

Just bought a new 4 core spi radiator to replace my old original leaking radiator and after 4 weeks it developed a leak at the cap seam just below the upper radiator hose. I rebuilt the engine; Arp head studs and new felpro gaskets. it now has 17,000 miles on it and has been running great all summer long. I used a new robertshaw 354 190*thermostat, with new coolant, the water pump is new from peninsular and I bleed the system during installation. What I want to know is what else besides a leaking head gasket could cause this? I don't have any bubbles at the overflow bottle and in the time I ran the new radiator I took a trip every weekend and only towed a light load once. Truck runs great I've been hittting almost 20mpg. any ideas?

[More Power]

The same thing happened to me back in the early 90's - a recently rebuilt copper/brass radiator sprung a leak in the same place as yours. I attributed it to insufficient solder. The shop fixed it, and it didn't leak again.

However, it's always a good idea to replace the radiator cap whenever the radiator is rebuilt. A garage or rad shop should have a pressure testing rad cap (has a gauge on it) that'll let you know if there's an overpressure issue happening.

Jim