SEAL-O-RING 5P2931 - Caterpillar

The folded core radiators were designed to be adaptable to its particular environment. Therefore, two module positions were designed. All vehicular applications except the off-highway trucks and tractors were designed with the "standard" gap arrangement. This gap is a wide 6.5 mm (.26") "trash" gap between adjacent modules on the downstream side of the radiator. The downstream side is the grill side of the radiator for a blower fan. Narrower 2.0 mm (.08") "clearance" gaps are at the upstream side of the radiator. See Illustration 1.
The approximate spacing of the cores is designated by the locating dimples in the top and bottom tanks and the dowels on the folded core end tanks. It is important on vehicular engines to maintain the 6.5 mm (.26") spacing on the downstream gaps while observing (not setting) the small 2.0 mm (.08") upstream gaps. See Illustration 1.
Illustration 1. Standard.The commercial folded cores for the 3400 and 3500 Families of Engines use the opposite or "reversed" gap position that provides better heat tranfer performance but is more sensitive to applications where debris exists. The "reversed" gap positions the 2.0 mm (.08") gap on the downstream side of the radiator while the 6.5 mm (.26") gap now is on the upstream side. The "reversed" gap positioning requires that the 2.0 mm (.08") gap on the grill side be adjusted and that the larger gaps be observed (not set) to be approximately 6.5 mm (.26"). See Illustration 2.
Illustration 2. Reversed.For both "standard" and "reverse" designs, the gaps should be close to the correct spacing with the strap assembly bolts loose. In both designs, only the downstream (grill side) gaps should be adjusted (6.5 mm standard - 2.0 mm reversed). Forcing the cores either closer or farther apart causes the core to bow in the middle since the cores are fixed at either end by the locating dowels. Excessive bowing could initiate stresses that could lead to failure of the module.