Engine Issues

Old Timer’s Compression Test

Get a 10mm fuel pump fitting (high Pressure) off a junk Volvo and weld it to an air hose type fitting or tap an old plug to accommodate a brass air fitting. This will allow you to do a cylinder leak test on each cylinder by hooking an air hose to the cylinder.

Here are the steps to follow:

1. You put the cylinder you want to test at top dead center;

2. Screw the fitting into the spark pug hole.

3. Apply some air pressure to do the “hiss test”:

a) listen at the tail pipe – for leaking exhaust valve;
b) listen at the carburetor – for leaking intake valve;
c) listen in the radiator – for leaking head gasket; and
d) listen in the oil filler cap- for leaking rings blow by.

Engine Won’t Start?

Due to Ignition Wiring Connections:
1.Loose or corroded connections at the ammeter, ignition switch, coil or distributor.
2.Low tension wire insulation cracked or worn through.
3.Poor low-tension wire ground connection.
4.Loose, corroded or burned ignition switch contacts.
5.Loose or corroded high tension terminals or cable sockets.
6.Cracked, oil soaked, wet chafed or worn high-tension cable insulation.
7.High tension cables installed in the wrong firing order
8.High tension cable from coil to distributor not connected.
9.Poor ground between coil and its mounting.
10.Poor ground between distributor and engine.

Distributor Issues:
1.Breaker point gap much too wide.
2.Incorrect ignition timing.
3.Breaker points dirty, cracked, pitted or burned.
4.Breaker arm spring weak or broken.
5.Breaker arm sticking.
6.Breaker arm grounded due to worn or broken insulating bushing.
7.Breaker arm rubbing block loose or badly worn.
8.Breaker arm plate loose or not properly grounded.
9.Loose breaker plate terminal posts.
10.Breaker pigtail Lead wires loose or broken.
11.Breaker cam loose due to burrs on cam locking screw taper.
12.Broken, loose or bent rotor spring.
13.Distributor cap cracked.
14.Distributor cap contacts bent, loose or badly burned.
15.Too much clearance between distributor cap inserts and rotor.
16.Grounded rotor.
17.Weak or grounded condenser
18.Distributor cap center terminal (rotor contact) missing or broken.
19.Distributor cap wet or dirty.
20.Broken,worn or bent distributor shaft.
21.Defective coil.
22.Distributor drive gear not properly meshed with oil pump drive gear.
23.Distributor drive gear or coupling sheared, broken or loose on shaft.

Due to Battery:
1. Low charge in battery
2.Dead cell in battery.
3.Poor ground connection between battery and frame.
4.Poor ground connection between frame and engine.
5.Battery terminals badly corroded or loose.
6.Cable from starter to battery broken, or terminal cracked. Cable may be corroded inside insulation if original and not be noticeable.
7.Cable from starter to battery is for 12 volt and not 6 volt (0 or 00 ga)

Due to Spark Plugs:
1.Plugs operating too cold, causing fouling.
2.Fouled plugs due to an excessively rich carburetor mixture or improper operation of choke
3.Fouled plugs due to engine oil blow-by, looseness or bad gasket.
4.Fouled plugs due to damaged or ineffective plug gaskets.
5.Use of too hot operating plugs, causing pre-ignition.
6.Spark plug gaps much too wide.

Due to Starting Motor:
1.Broken starter pinion.
2.Broken flywheel ring gear.
3.Sticking starter due to burred tooth on starter pinion or flywheel gear.
4.Broken Bendix spring.
5.Oil congealed in starter drive
6.Starting switch not operating properly.
7.Starting switch not grounded properly. Switch contacts burned or corroded.
8.Rotation of starter prevented due to teen armature shaft, cracked or distorted housing, tight bearings, misaligned bearings, lack of lubrication, sludge formation in starter drive, starter not aligned properly with engine.
9.Rotation of starter prevented due to timed loose brush connections, loose pigtails, brushes sticking in holders, bent brush plate holder arms, weak or broken brush springs, sticking brush holders, incorrect type of brushes, brushes worn too short.

Due to Fuel System:
1.Intake manifold and cylinders flooded with fuel due to faulty choke operation.
2.Old, stale or a poor grade of fuel being used, (particularly during cold weather)
3.Air leaks due to cracked intake manifold, worn throttle shaft, loose manifold nuts, loose carburetor attaching nuts, warped carburetor flange, broken or damaged intake manifold or carburetor gaskets, poor vacuum line connection at the intake manifold, loose or missing intake manifold core hole plugs or warped choke cover.
4.Choke valve fails to close fully when starting a cold engine. Broken or loose choke wire?
5.Low carburetor float or fuel level.
6.Clogged or dirty fuel pick-up.
7.Inoperative fuel pump.
8.Restricted, broken or clogged fuel line from the pump to carburetor.
9.Restrictions in carburetor passages due to presence of ice, corrosion or water.
10.No fuel supply.
11.Vapor lock.

Due to Lack of Engine Compression:
1.Spark plugs loose in cylinder head.
2.Cylinder head bolts loose.
3.Piston rings which are broken, badly worn, weak or stuck.
4.Cylinder head gasket damaged or improperly installed.
5.Valves held open due to insufficient tappet clearance.
6.Valves held open due to warped corroded or gummed stems.
7.Valve seating poorly.
8.Valve springs weak or broken.

Tech Tip # 1- Vacuum leaks:
The early Chevy 235 was notorious for vacuum leaks. If you have a problem idling which improves with more choke, you may have a vacuum leak. First, see if you can isolate the leak. With the engine warm and idling, begin disconnect vacuum lines and plugging the line vacuum port at the manifold. This would include the vacuum wipers, hydrovac, and crankcase breather. If the engine improves with plugging, you found the culprit. If none make a difference, it is at the carburetor or intake manifold gasket. The design of the original manifold lent itself to creating small leaks and can be a troublesome nuisance

Engine Misses at one Cylinder

Due to Ignition Wiring:
1.Loose or corroded high tension terminal or cable socket.
2.Cracked, oil soaked, wet, chafed or worn high tension cable insulation.
3.High tension cable not connected.
4.Broken wire inside of cable.
5.Stray cable strand shorting spark plug.

Due to Spark Plug:
1.Spark plug operating too cold, causing fouling.
2.Spark plug operating too hot, causing pre-ignition.
3.Fouled plug due to blow by.
4.Fouled plug due to its being loose or ineffective plug gasket
5.Spark plug gap too wide.
6.Spark plug gap too narrow.
7.Insulator loose in shell or insulator coated with carbon, oil or water.
8.Insulator cracked, glaze-scratched or melted, allowing carbon deposit etc., to provide path for current.
9.Spark plug gap filled with oil, water or fuel.
10.Spark plug threads dirty.

Due to Valve System:
1.Valve leaks due to faulty seating.
2.Warped valve face.
3.Shoulder on valve face.
4.Valve sticking.
5.Valve burned.
6.Carbon on valve seat.
7.Valve pitted.
8.Cracked valve seat.
9.Gum on valve stem.
10.Broken valve spring.
11.Bent valve stem.
12.Valve stem too tight in guide.
13.No or incorrect tappet clearance.
14.Sticking rocker arm.
15.Broken mushroom on lifter assembly.

Due to other Conditions:
1.Cracked cylinder head.
2.Broken cylinder head gasket.
3.Distributor cap dirty, loose or badly burned.
4.Air leak around intake valve stem due to excessive stem-to-guide clearance.
5.Loss of engine compression in cylinder.
6.Slight water leak in cylinder or combustion chamber.
7.Ignition points too close with low lobe on cam and worn distributor shaft or loose bushing

Engine Misfires/Skips at Idle

Due to Ignition:
1.Loose or corroded connections or terminals at the ammeter, ignition switch, coil or distributor.
2.Slight short in primary circuit wiring.
3.Poor low tension wire ground connection.
4.Loose, corroded or burned ignition switch contacts.
5.Loose or corroded high tension terminals or cable sockets.
6.Cracked, oil soaked, wet, chafed or worn high tension cable insulation.
7.Poor ground between coil and its mounting.
8.Poor ground between distributor and engine.
9.Breaker point gap incorrect.
10.Breaker points not synchronized properly.
11.Breaker points dirty, cracked pitted or burned.
12.Breaker arm spring weak or broken.
13.Breaker arm sticking.
14.Breaker arm insulating bushing worn.
15.Breaker arm plate loose or note properly grounded.
17.Loose breaker plate terminal posts.
18.Breaker plate pigtail leads loose or broken.
19.Breaker cam with low lobe.
20.Breaker cam loose due to burrs on cam locking screw taper.
21.Incorrect ignition timing.
22.Distributor cap cracked, wet or dirty.
23.Distributor cap inserts bent, loose or badly burned.
24.Distributor shaft bent or worn.
25.Distributor shaft bushing or bearing loose or worn.
26.Weak condenser.
27.Defective coil.
28.Cracked, wet or dirty coil tower.
29.Defective spark plug or coil radio suppressor.
30.Defective spark plugs.
31.Spark plugs not gapped properly.
32.Weak battery.
33.Ruptured automatic advance diaphragm.

Due to Fuel System:
1.Float level too high or too low.
2.Idle adjusting screws (dual carburetors) not properly balanced.
3.Throttle valves (dual carburetors) not properly synchronized.
4.Restricted or partially clogged idle air passage.
5.Restricted or partially clogged idle jet or passage.
6.Air leaking around throttle shaft.
7.Air leaking around idle tube.
8.Loose manifold connections.
9.Air leak in vacuum lines.
10.Loose manifold nuts.
11.Broken or damaged carburetor or intake manifold gaskets.
12.Cracked intake manifold.

Starter not operating properly or inoperative

Check for:

1. Battery in low state of charge.
2. Battery completely discharged.
3. Poor ground connection between battery and frame or from frame to engine.
4. Battery terminals badly corroded or loose.
5. Cable from battery to starter broken or terminal cracked.
6. Broken starter pinion.
7. Broken flywheel ring gear.
8. Sticking starter due to burred teeth on starter pinion or flywheel ring gear.
9. Broken Bendix spring.
10. Use of engine oil which is too heavy – especially in cold weather.
11. Starting switch not operating properly.
12. Starting switch not grounded properly.
13. Rotation of starter excessively resisted due to bent armature shaft, cracked or distorted housing, tight bearing, mis-aligned bearings, lack of lubrication sludge formation in starter drive’ starter not aligned properly with engine.
14. Improper functioning of starter brushes due to loose brush connections, loose pigtails, brushes sticking in holders, bent brush holder arms, weak or broken brush springs, sticking brush holders, incorrect type of brushes, brushes worn too short.
15. Armature shorted.
16. Commutator surface dirty, burned, pitted excessively lubricated.
17. High mica between commutator segments due to worn commutator.
18. Brush ring set incorrectly or grounded.
19. Excessive brush spring tension – causing rapid wear of brushes and commutator.
20. Burned out, shorted or open-circuited field coils.
21. Worn bushings or bearings causing armature to drag against pole pieces.
22. Battery cables undersize.
23. Winding thrown from armature.

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Frequent battery charging necessary

Due to Internal Battery Conditions:

1. Ineffective battery plate separators.
2. Plates badly sulphated.
3. A Ieak in cell due to crack, or scaling compound not sealing properly.
4. Water level not maintained at proper height.

Due to Excessive Load:

1. Stop light switch closed at all times.
2. Tail and stop damp wires reversed.
3. Use of too high candle power headlamp bulbs.
4. Car operation confined mostly to night driving.
5. Excessive use of spot lamps, radio, car heater, cigar lighter or defroster.
6. Lighting circuit grounded or shorted.
7. Using headlamps excessively while car is parked.

Due to Generator Condition:

1. Generator inoperative.
2. Fan belt slipping.
3. Incorrect size generator drive pulley.
4. Ammeter indicating higher charging rate than actual.
5. Generator regulator not adjusted properly.
6. Engine idle too low, particularly on cars with free wheel and overdrive.
7. Loose external circuit connections.
8. Corroded battery terminals and/or ground connection.

Due to Starter:

1. Starter commutator badly worn or burned.
2. High mica between commutator bars.
3. Use of starter too frequently.
4. Excessive use of starter due to starting difficulties.

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Excessive engine temperature

Due to Pre-Ignition:

1. Ignition timed too early.
2. Weak distributor automatic advance springs.
3. Combustion chamber with large carbon deposits.
4. Spark advance not operating upon acceleration.
5. Use of spark plugs which arc too hot.
6. Spark plug electrodes or insulators burned or carbonized.
7. Sharp metallic edges in combustion chamber.
8. Cylinder head gasket projecting into combustion chamber.
9. Excessively lean carburetor mixture.
10. Automatic heat control valve held in closed position.
11. Poor grade of fuel being used.
12. Stale fuel which has lost volatility.
13. Using a high compression cylinder head with standard fuel.
14. Hot engine valves caused by incorrect valve seat width.
15. Hot engine valves caused by insufficient valve tappet clearance.
16. Hot engine valves due to use of wrong type.
17. Hot engine valves due to their having thin edges.

Due to Water Loss:

1. Radiator leak.
2. Any water hose leakage.
3. Leaky cooling system drain plug valve.
4. Leaky water pump.
5. Broken water pump gasket – or air cooling system gasket.
6. Cracked cylinder head or block causing an internal or external leak.
7. Water loss through overflow pipe especially when engine is overheated. 8. Radiator upper tank baffle plate loose.
9. Loose cylinder head cap screws or broken cylinder head gasket, allowing combustion gases to leak into the cooling system, causing overheating.
10. Loss of water at high speed due to an air leak at the water pump packing gland.
11. Loose or corroded water jacket cover plate.

Due to Other Conditions:

1. Ignition timed too late.
2. Slipping fan belt.
3. Radiator core covered with dirt or heavy paint.
4. Radiator core surface restricted by license plate or emblems.
6. Heavy sludge or dirt accumulation in engine block.
7. Water manifold rusted, loose or damaged.
8. Engine thermostat not installed properly or not opening.
9. Collapsed or deteriorated water hose.
10. Water pump impeller loose on shaft.
11. Too much clearance between pump housing and impeller.
12. Use of certain types of anti-freeze solution during warm weather periods.
13. Water transfer holes in cylinder block or cylinder head restricted. 14. Cylinder head gasket installed in such a manner so as to restrict the flow of water.
15. Fan blades not pitched properly.
16. Using a rear axle gear ration which is too fast, or oversized tires in mountainous regions.
17. Brakes dragging.
18. Wheel bearings too tight.
19. Clutch slipping.
20. High frictional resistance in engine caused by: Insufficient oil circulation, Internal clearances of engine parts insufficient. Internal engine parts not aligned. Use of too heavy a grade engine oil.
21. High frictional resistance in power train transmitting units.
22. A floating foreign object in cylinder head which occasionally restricts water circulation.
23. Screen for hugs in front of radiator too fine.

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Water pump noise

Check for:

1. Water pump shaft pulley loose.
2. Impeller loose on shaft.
3. Too much end play in pump shaft.
4. Too much clearance between water pump shaft and bushings.
5. Impeller blades rubbing against water pump housing.
6. Impeller pin sheared off or impeller broken.
7. Rough bearing.
8. Water pump seal too hard.

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Fan & fan belt noise

Check for:

1. Bent or distorted fan blades.
2. Fan blades not pitched properly.
3. Fan shad bushing loose.
4. Improper lubrication of fan shaft bushing.
5. Excessive fan shaft end play.
6. Unbalanced fan blade assembly.
7. Fan hub loose and turning on shaft.
8. Fan blades loose on hub or spider.
9. Fan blades striking radiator core or fan belt.
10. Any drive pulley cracked or distorted.
11. Fan belt pulleys misaligned.
12. Belt too tight causing squeak.
13. Belt too loose causing squeak upon acceleration.
14. Dirt, grease, rust or other foreign matter on belt or pulleys.
15. Incorrect fan belt being used.
16. Belt worn or badly burned.