1577130 Valve-Exhaust Fits Caterpillar ModelsOne New Aftermarket Replacement Exhaust Valve Fits Caterpillar (Fits CAT) 3126 Series Engines This aftermarket replacement exhaust valve is Fits Caterpillar 3126 series inline 6 cylinder diesel engine. The exhaust valve seats in the cylinder head and controls the release of combustion gases from each cylinder. Per OEM specifications for the 3126 engine, the exhaust valve head diameter is 40. 00 mm (1. 575 in) with a 45 degree valve face angle, and the