Compression Test - DeWalt DW168F Manual

sTaRT MEChanIsM
waRnIng: Risk of explosion. Spilled gas o line and it's vapors can be come ignited
from sparks from smoking products, electrical arcing, exhaust, flame, gas es and hot engine
components such as the muffler. Make sure there are no sources of ignition, such as
smoking products near servicing location. Wipe any fuel spillage from engine.
1. If the engine is equipped with a D
e
starter, push the start control to START and check
for crankshaft rotation. noTE: Ensure a fully
charged 18V D wALT battery is being used.
e
a. If the crankshaft does not rotate, pull the recoil
start cord. If the crankshaft rotates the electric
starter or connection to battery is faulty. Inspect
and repair.
b. If the battery start switch is engaged and the
electric motor can be heard running the problem
is with the drive pinion gear, service the starter
motor. If the electric motor can not be heard run-
ning the problem is electrical. See the starter Motor Inspection section.

CoMpREssIon TEsT

1. Remove the spark plug and thread in compression
gauge.
2. Use pull starter to simulate starting engine (pull
briskly) or use fully charge battery pack if electric
start. Compression gauge should read 40 psi min.,
if lower than 40 psi check valve clearance before
proceeding further.
3. If valve clearance is in spec and compression is
still low, check head gasket and then piston rings
and cylinder bore for wear.
hInT: Only use a peak compression gauge when
doing a compression test. Leak down testers can only
measure decay with the piston at TDC.
wALT battery
22