TM 5-3810-307-24-2-2
Cylinder Block General Information
The B-Series engine is available in 4 cylinder or 6 cylinder versions.
Most parts are common between the 4 and 6 cylinder versions (e.g. pistons, rings, connecting rods, water pump).
In general, the only parts that differ between the 4 and 6 cylinder versions are those that must change due to the
difference in number of cylinders (e.g. crankshaft, block casting, cylinder head, etc).
Camshaft:
The camshaft end clearance is determined by the clearance between the camshaft and the thrust plate.
Camshafts that are damaged or worn on the fuel transfer pump lobe or valve lobes must be replaced. Cummins
Engine Company Inc. does not recommend the grinding of camshaft lobes.
Crankshaft:
The crankshaft is a balanced, forged steel, full fillet hardened unit. The 4 cylinder crankshaft has 5 main bearing
journals and the 6 cylinder crankshaft has 7 main bearing journals. All of the upper main bearing shells are the
same except for the next to last journal which uses a flanged upper bearing shell. The flanges on the upper bearing
shell control the end thrust of the crankshaft.
Oversize main bearings, thrust bearings, and connecting rod bearings are available for service. Cummins Engine
Company, Inc. recommends regrinding ALL of the main bearing or the connecting rod journals when ONE requires
regrinding.
Cylinder Block
The cylinder block has provisions for the oil cooler housing, thermostat seats, coolant bypass line, water pump
volute, oil pump housing, water pump inlet, and bored piston cylinders with spacing between cylinders to provide
room for dry liners, if needed for service.
Oil Seals
All crankshaft seals on the B Series are Teflon lay-down lip (scroll) type. The Teflon lay-down lip type seal does not
contain a spring on the back of the sealing lip. The sealing lip is a thin, stiff piece of Teflon.
Teflon seals must be dry before installation. Do not lubricate the seal lip or the shaft.
After the first few turns of the shaft, a thin film of Teflon is transferred from the seal lip to the shaft. if the shaft or
seal is not clean and dry, this transfer will not occur and the seal will leak.
Pistons
The pistons have a cast aluminum body and 3 ring grooves. The top ring groove on turbocharged engines has a ni-
resist insert with a Keystone profile. The pistons for different engine configurations are similar in appearance, but
are not interchangeable. Always check the part number to be sure the correct piston is used during piston
replacement.
Vibration Damper
Six cylinder engines are equipped with a vibration damper to control the torsional vibration of the crankshaft. A
vibration damper is engineered for use on a specific engine model.
It is not economical to repair a vibration damper in the field. Install a new or a rebuilt damper it inspection indicates
the damper is defective.
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