TM 5-3895-346-14
SHOP NOTES
ENGINE OVERHAUL
CYLIDER BLOCK
SHOP NOTES - TROUBLESHOOTING -
SPECIFICATIONS - SERVICE TOOLS
SHOP NOTES
TEFLON-WRAPPED PIPE PLUGS
Pipe plugs with a baked teflon coating are available for service. However, pipe plugs can be hand wrapped
satisfactorily with teflon tape to provide a better seal and facilitate plug removal. When a teflon-wrapped plug
is installed, it is extremely important that the specified torque not be exceeded.
Hand wrap a pipe plug with teflon tape as follows:
1. Be sure the pipe plug is thoroughly clean and dry prior to applying the teflon tape. All dirt, grease, oil,
and scale must be removed.
2. Start the tape one or two threads from the small or leading edge of the plug, joining the tape together
with an overlap of approximately 1/8 inch.
3. Wrap the tape tightly in the same direction as you would turn a nut. The tape must conform to the
configuration of the threads (be pressed into the minor diameter of the threads) without cutting or ripping the
tape.
4. Hand tighten and hand torque the pipe plug and DO NOT exceed the specified torque. DO NOT use
power tools.
CHECKING BEARING CLEARANCES
A strip of soft plastic squeezed between the crankshaft journal and the connecting rod bearing or main
bearing may be used to measure the bearing clearances.
The strip is a specially molded plastic wire manufactured commercially and is available in three sizes and
colors. Type PG-1 (green) has a clearance range of 0.001 to 0.003 inch, type PR-1 (red) has a range of 0.002
to 0.006 inch, and type PB-1 (blue) has a range of 0.004 to 0.009 inch.
The plastic strip may be used for checking the bearing clearances as follows:
1. Remove the bearing cap and wipe the oil from the bearing shell and crankshaft journal.
CAUTION
When checking the main bearing clearances with the engine in a position where the main bearing caps are
supporting the weight of the crankshaft and the flywheel, an erroneous reading, due to the weight of the
crankshaft and flywheel, can be eliminated by supporting the weight of the crankshaft with a jack under the
counterweight adjoining the bearing being checked.
2. Place a piece of the plastic strip the full width of the bearing shell, about 1/4 inch off center (Fig. 1).
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