20 Engine 5-4 General Information, Diagnosing Malfunctions Model 2120 Tractor TM-4252 (Dec-70) Incorrect engine timing HIGH OIL PRESSURE Defective water pump Stuck or improperly adjusted regulating valve Too low crankcase oil level Stuck or damaged filter by-pass valve Defective radiator cap EXCESSIVE FUEL CONSUMPTION HIGH OIL CONSUMPTION Engine overloaded Oil control rings worn or broken Compression too low Scored cylinder liners or pistons Leaks in fuel system Excessive resistance in air intake system Air cleaner restricted or dirty Oil passages restrict free oil flow Fuel injectors dirty or faulty Worn valve guides or stems Injection pump defective (delivers too much fuel) Too low viscosity crankcase oil Incorrect engine timing Excessive oil pressure Piston ring grooves excessively worn BLACK OR GREY EXHAUST SMOKE Piston rings sticking in ring grooves Excess fuel Insufficient piston ring tension Engine overloaded Piston ring gaps not staggered Air cleaner restricted or dirty Defective muffler (causing back-pressure) Excessive main or connecting rod bearing clearance Fuel injectors dirty or faulty Crankcase oil level too high Incorrect engine timing External oil leaks Front and rear crankshaft oil seal faulty WHITE EXHAUST SMOKE LOW OIL PRESSURE Engine compression too low Low crankcase oil level Defective fuel injectors Leakage at internal oil passages Incorrect engine timing Defective oil pump Thermostat defective Excessive main and connecting rod bearing clearance COOLANT IN CRANKCASE Cylinder head gasket defective Improper regulating valve adjustment Improper crankcase oil Cylinder head or block cracked Defective oil pressure warning switch or indicator lamp Printed in Germany