Before disassembling any part of the engine to correct lifter noise, check the engine oil pressure. See
Engine/Lubrication - Diagnosis and Testing
.
Check engine oil level. The oil level in the pan should never be above the MAX mark on dipstick, or below the
MIN mark. Either of these two conditions could cause noisy lifters.
OIL LEVEL TOO HIGH
If oil level is above the MAX mark on dipstick, it is possible for the connecting rods to dip into the oil while
engine is running and create foaming. Foam in oil pan would be fed to the hydraulic lifters by the oil pump
causing them to become soft and allow valves to seat noisily.
OIL LEVEL TOO LOW
Low oil level may allow pump to take in air which when fed to the lifters it causes them to become soft and
allows valves to seat noisily. Any leaks on intake side of pump, through which air can be drawn, will create the
same lifter noise. Check the lubrication system from the intake strainer to the oil pump cover, including the
relief valve retainer cap. When lifter noise is due to aeration, it may be intermittent or constant, and usually
more than one lifter will be noisy. When oil level and leaks have been corrected, the engine should be operated
at fast idle to allow all of the air inside of the lifters to be bled out.
VALVE TRAIN NOISE
To determine source of valve train noise, operate engine at idle with cylinder head covers removed and listen
for source of the noise.
Valve lifter noise ranges from light noise to a heavy click. A light noise is usually caused by excessive leak-
down around the unit plunger which will necessitate replacing the lifter, or by the plunger partially sticking in
the lifter body cylinder. A heavy click is caused either by a lifter check valve not seating, or by foreign particles
becoming wedged between the plunger and the lifter body causing the plunger to stick in the down position.
This heavy click will be accompanied by excessive clearance between the valve stem and rocker arm as valve
closes. In either case, lifter assembly should be removed for inspection.
Removal
REMOVAL
NOTE:
Worn valve guides or cocked springs are sometimes mistaken for noisy lifters.
If such is the case, noise may be dampened by applying side thrust on the valve
spring. If noise is not appreciably reduced, it can be assumed the noise is in the
tappet. Inspect the rocker arm push rod sockets and push rod ends for wear.
2010 Jeep Wrangler Sport
2010 ENGINE 3.8L - Service Information - Wrangler
viernes, 1 de octubre de 2021 05:18:31 p. m.
Page 118
© 2011 Mitchell Repair Information Company, LLC.
