Ford COUGAR 1968 Shop Manual page 311

PART 8-1
-
General Engine Service
F I G . 47
(Continued)-Engine Diagnosis
Guide
NOISY ENGINE
LOW ENGINE
OIL PRESSURE
NOISY HYDRAULIC
VALVE LIFTER
Check for vacuum leaks, discon- check for air delivery.
nected hoses or missing caps.
Drive belt slipping over pump pul-
ley indicates pump seizure.
THERMACTOR AIR PUMP
Air pump adjusting arm bracket
NOISE
bolt (at pump) too long.
The Thermactor air pump like any IGNITION
engine driven accessory may produce
a detectable sound with the hood Incorrect initial ignition timing
raised. This sound level, however, is causing spark ping or knock.
not noticeable in the passenger com-
Incorrect distributor advance caus-
partment.
ing spark ping or knock.
On occasion a new air pump may
Low octane fuel.
produce a slight squealing sound on
initial operation until the lip of the
ENGINE
pump seal on the centrifugal filter. fan
wears in, and the pump vanes may Leaking intake manifold gasket.
produce intermittent chirping, squeak- Loose engine mounting bolts or
ing, or knocking sounds at low engine
worn engine support insulator(s).
speeds until the pump wears in. Al-
Cylinder head bolts not properly
though factory break-in should have
torqued.
eliminated these sounds, some mileage
Crankcase ventilation regulator val-
(30 miles or more) may be required on
ve defective or a restricted vent tube.
new vehicles to provide adequate air
Improper valve clearance.
pump break-in. Worn camshaft lobes.
If air pump sounds are considered
Perform a manifold vacuum or com-
objectionable, check the following: pression test to determine which me-
Drive belt improperly adjusted or
chanical component. is at fault.
drive pulley misaligned.
Loose mounting bracket.
Air hoses disconnected or leaking.
Hoses making contact with body
EXHAUST SYSTEM
parts.
Defective centrifugal air filter fan.
Air bypass valve vacuum line col-
Defective air pressure relief valve.
lapsed, plugged, di~connected or leak-
Wrong pressure setting plug (relief
ing-causing backfire.
valve), broken spring, or plug missing.
Defective or malfunctioning air by-
Then, if it is determined that noise
pass valve-ca'Jsing backfire.
is coming from the air pump, and if
Defective or malfunctioning distri-
the noise is diagnosed as a pump pro-
butor Vacuum advance control valve-
blem, the pump should be replaced.
causing backfire.
Exhaust system leak; exhaust mani-
THERMACTOR AIR
fold-to-cylinder head, muffler inlet pipe
PUMP INOPERATIVE
flange gasket, or loose muffler con-
Remove air pump outlet hose to nections.
To properly diagnose a complaint low oil pressure 'indication:
of low engine oil pressure the follow- ( a ) If the vehicle is equipped with
ing procedure should be used: a- pressure gauge, check the constant
1. Operate the engine to stabilize voltage regulator and oil pressure send-
temperatures. ing unit for malfunction.
2. Install a direct reading oil pres- (b) If the vehicle is equipped with
sure gauge with a scale of 0-100 psi (a an indicator light, check for correct
larger scale is not accurate enough). oil pressure sending unit.
3. Refer to specifications for the 5. If the oil pressure is below the
accepted hot oil pressure at ZOO0 rpm. minimum requirement, determine if the
4. If the oil pressure is within problem is in the oil pump, galley
specifications, check the following for plugs or excessive bearing clearance.
A noisy hydraulic valve lifter can a shock will be felt when the valve
be located by operating the engine at
seats.
idle speed and placing a finger on the Another method of identifying a
face of the valve spring retainer. If noisy lifter is by the use of a piece
the lifter is not functioning properly,
of hose. With the engine operating