Cessna 150 Series Service Manual page 138

11-32. TROUBLE SHOOTING.
TROUBLE PROBABLE CAUSE REMEDY
NO OIL PRESSURE.
No oil in sump. Fill sump with proper grade and
quantity of oil. Refer to Section 2.
Oil pressure line broken, Replace or connect.
disconnected or pinched.
Oil pump defective. Remove and inspect. Examine
engine. Metal particles from
damaged pump may have entered
engine oil passages.
Defective oil pressure gage. Check with another gage.
Replace if defective.
Oil congealed in gage line. Disconnect line at engine and gage;
flush with kerosene. Pre-fill with
kerosene and install.
Relief valve defective. Remove and check for dirty or
defective parts. Clean and in-
stall; replace defective parts.
LOW OIL PRESSURE. Low oil supply.
Replenish. Refer to Section 2.
Low viscosity oil. Drain sump and refill with
proper grade and quantity of oil.
Oil pressure relief valve spring Replace weak or broken spring.
weak or broken. Dirt on seat. Clean plunger and seat.
Defective oil pump.
Remove and inspect. Examine
engine. Metal particles from
damaged pump may have entered
engine oil passages.
Secondary result of high oil Observe oil temperature gage for
temperature. high indication. Determine and
correct reason for high oil tem-
perature.
Plugged oil screen. Remove and clean screen.
Oil pressure gage defective. Check with another gage.
Replace if defective.
Oil pressure relief valve Remove and clean plunger.
plunger sticking.
Oil pump suction tube screen Engine overhaul required.
plugged or internal oil leak.
HIGH OIL PRESSURE. High viscosity oil. Drain sump and refill with proper
grade and quantity of oil.
Defective oil pressure gage. Check with another gage. Replace
if defective.
Relief valve defective. Remove and check for dirty or de-
fective parts. Clean and install;
replace defective parts.
11-13