Basic Trouble Shooting-Air Cooled VW Engine

Trouble Shooting

Engine and performance
Engine will not rotate when attempting to start

Check for loose battery terminal connections or corrosion.

Battery is discharged or faulty.

The Automatic Stick Shift is not in Neutral.

There could be broken, loose or disconnected wiring in the starting circuit.

The starter motor pinion is jammed in the flywheel ring gear.

The starter solenoid is faulty.

The starter motor is faulty.

The ignition switch is faulty.

The starter pinion or flywheel teeth are worn or broken.

Engine rotates but will not start

The fuel tank is empty.

Battery is discharged (engine rotates slowly).

Battery terminal connections are corroded or loose.

There might be leaky fuel injector(s), a faulty cold start valve, fuel pump, pressure regulator, etc.

Fuel is not reaching the main ring or other fuel injection problems.

Fuel is not reaching the carburetor.

The ignition components are damp or damaged.

Worn, faulty or incorrectly gapped spark plugs.

There are broken, loose or disconnected wiring in the starting circuit.

The ignition points are incorrectly gapped.

There are broken, loose or disconnected wires at the ignition coil or even a faulty coil.

Engine is hard to start when it is cold.

The battery is discharged or low.

The choke is defective or not adjusted properly.

You have a malfunctioning fuel system.

There is a faulty cold start injector.

The injector(s) are leaking.
The ignition system is faulty.
Engine is hard to start when it is hot.

The air filter could be clogged.

The fuel is not reaching the fuel pump, carburetor or fuel injection system.

The battery connections are corroded, especially the ground.

The starter motor is worn.

There are leaking injector(s)

The thermo-time switch is defective.

The choke is defective or not adjusted properly.

The starter motor is noisy or it is excessively rough in engagement.
The flywheel gear teeth or pinion is worn or broken.

The starter motor mounting bolts are loose or missing.

Engine starts but stops immediately.

There are loose or faulty electrical connections at the coil or the distributor.

The coil is defective.

There is insufficient fuel reaching the carburetor or fuel injector(s).

There is a vacuum leak at the gasket between the intake manifold/plenum and throttle body.

The pilot jet cutoff valve is defective.

There is an oil puddle under engine.

The oil strainer cover plate or drain bolt washer is leaking.

The oil pressure-sending unit is leaking.

The valve cover is leaking.

The pushrod tubes are leaking.

The oil cooler or oil cooler seals are leaking.

The engine oil seals are leaking.

The engine lopes while idling or the idle is erratical.

The is a vacuum leak.

There is a leaking EGR valve.

The air filter is clogged.

The fuel pump is not delivering sufficient fuel.

The timing gears are worn.

The camshaft lobes are worn.
The throttle body ports are clogged.

The carburetor is misadjusted or worn.

The engine misses at idle speed.

The spark plugs are worn or not gapped properly.

There are faulty spark plug wires.

There are vacuum leaks.

The ignition timing is incorrect.

There is uneven or low compression.

The air/fuel mixture is incorrect.

Engine misses throughout the driving speed range.

The fuel filter/carburetor/injectors are clogged and/or there are impurities in the fuel system.

The fuel output at the injector(s) is low.

There are incorrectly gapped spark plugs.

The ignition timing is incorrect.

The distributor cap or rotor is cracked.

There are leaking spark plug wires.

The emission system components are faulty.

The cylinder compression pressures are low or uneven.

The ignition system is weak or faulty.

There is a vacuum leak in the fuel injection system, intake manifold, air regulator valve or vacuum hoses.

The engine stumbles on acceleration

The spark plugs are fouled.

The carburetor/fuel injection system needs adjustment or repair.

The fuel filter is clogged.

The ignition timing is incorrect.

There is an intake manifold vacuum leak.

Engine surges while holding the accelerator steady.

The is an intake air leak.

The fuel pump is faulty.

The fuel injector electrical connectors are loose.

The ECU is defective.

The airflow sensor is damaged.

The engine stalls.

The idle speed is incorrect.

The fuel filter is clogged and/or there are water and impurities in the fuel system.

The distributor components are damp or damaged.

The emissions system components are faulty.

The spark plugs are faulty or incorrectly gapped.

The spark plug wires are faulty.

The is a vacuum leak in the intake manifold or vacuum hoses.

The valve clearances are incorrectly set.

The pilot jet cutoff valve is defective.

The engine lacks power.

The ignition timing is incorrect.

There is excessive play in the distributor shaft.

The rotor, distributor cap, points or wires are worn.

The spark plugs are faulty or incorrectly gapped.

The carburetor or fuel injection system are out of adjustment or excessively worn.

The coil is faulty.

The brakes are binding

The fluid level on the Automatic Stick Shift is incorrect.

The clutch is slipping.

The fuel filter is clogged and/or there are impurities in the fuel system.

The emission control system is not functioning properly.

The cylinder compression pressures are low or uneven.

The exhaust system is plugged.

The engine backfires.

The emission control system is not functioning properly.

The ignition timing is incorrect.

The secondary ignition system (cracked spark plug insulator, faulty plug wires, distributor cap and/or rotor) is faulty.

The carburetor/fuel injection system is in need of adjustment or excessively worn.

There is a vacuum leak at the fuel injector(s), intake manifold, air regulator valve or vacuum hoses.

The valve clearances are incorrectly set and/or the valves are sticking.

There is pinging or knocking engine sounds during acceleration or going uphill.

The grade of fuel is incorrect.

The ignition timing is incorrect.

The carburetor/fuel injection system is in need of adjustment.

The spark plugs or wires are improper or damaged.

The ignition components are worn or damaged.

The emission system is faulty.

There is a vacuum leak.

Engine runs with oil pressure light on.

The oil level is low.

The idle rpm is below specification.

There is a short in the wiring circuit.

The oil pressure sender is faulty.

The engine bearings and/or oil pump is worn.

Engine diesels (continues to run) after switching it off.

The idle speed is too high.

The engine operating temperature is excessive.

The pilot jet cutoff valve is defective.

The battery will not hold a charge.

The alternator/generator drivebelt is defective or not adjusted properly.

The battery electrolyte level is low.

The battery terminals are loose or corroded.

The alternator/generator is not charging properly.

The wiring in the charging circuit is loose, broken or faulty.

There is a short in the vehicle wiring.

The battery is internally defective.

The alternator/generator light fails to go out.

The alternator/generator or charging circuit is faulty.

The alternator/generator drivebelt is defective or out of adjustment.

The alternator/generator voltage regulator is inoperative.

The alternator/generator light fails to come on when the key is turned on.

The warning light bulb or the circuit is defective.

Fuel system

Excessive fuel consumption

The air filter element is dirty or clogged.

The ignition timing is incorrectly set.

The emissions system is not functioning properly.

The carburetor/fuel injection internal parts are excessively worn or even damaged.

The tire pressure is low or the tire size is incorrect.

There is fuel leakage and/or fuel oder.

The fuel feed or return line is leaking.

The tank was overfilled.

The evaporative canister filter is clogged.

The fuel injector internal parts are excessively worn.

The fuel injector(s) are leaking.

The carburetor is worn.

Cooling system

Overheating

The drivebelt is slipping.

The fan air intake behind the shroud is blocked or restricted.

The thermostat is faulty.

The ignition timing is incorrect.

The air/fuel mixture is incorrect.

Overcooling

The thermostat is faulty.

Clutch

The pedal travels to the floor with no pressure or very little resistance.

The release bearing or fork is broken.

The diaphragm spring in the clutch pressure plate has collapsed.

High pedal effort

The clutch cable is worn.

The clutch release shaft/housing is worn.

You are unable to select the gears.

The transaxle is faulty.

The clutch disc is faulty.

The pressure plate is faulty.

The pressure plate-to-flywheel bolts are loose.

The coupling pin on the shift rod is loose or missing.

Clutch slips (engine speed increase with no increase in vehicle speed)

The clutch plate is worn.

The clutch plate is soaked by oil by the leaking rear main seal or the transaxle input shaft seal.

The clutch plate is not seated. It may take 30 or 40 normal starts for a new one to seat.

The pressure plate or flywheel is warped.

The clutch springs are weak.

The clutch plate is overheated and needs to be allowed to cool.

Grabbing (chattering) as clutch is engaged.

There is oil on the clutch plate lining, the facings are burned or glazed.

The engine or transaxle mounts are worn or loose.

The pressure plate or flywheel is warped.

The resin is burned or smeared on the flywheel or the pressure plate.

There is noise in the clutch area.

The release shaft is improperly installed.

The bearing is faulty.

There is failure in the clutch plate damper spring.

Clutch pedal stays on floor.

The release cable is binding.

The release bearing or fork is broken.

Manual transaxle

There is knocking noise at low speeds.

The driveaxle constant velocity (CV) joint(s) are worn.

Noise most pronounced when turning.

There is differential gear noise.

Clunk on acceleration or deceleration

The engine or transaxle mounts are loose.

The differential pinion shaft in case if worn.

The damaged driveaxle CV joints are worn.

Vibration

The wheel bearing is rough.

The driveaxle is damaged.

The tires are out of round.

The tire is out of balance.

The CV joint is worn.

Noisy in neutral with engine running

The input gear bearing is damaged.

Noisy in one particular gear

The constant mesh gears are damaged or worn.

The synchronizers are damaged or worn.

The reverse fork is bent.

The fourth speed gear or output gear is damaged.

The reverse idler gear of idler bushing is worn or damaged.

Noisy in all gears

The is insufficient lubricant.

The bearings are damaged or worn.

The input gear shaft is worn or damaged.

Slips out of gear

The linkage is worn or improperly adjusted.

The transaxle/engine mounts are loose or worn.

The shift linkage doesn’t work freely or binds.

The shift for is worn.

Leaks lubricant

The final drive flange seal are worn.

The is an excessive amount of lubricant in the transaxle.

The axle boot is torn.

The axle tube retainer gasket is leaking.

Locked in gear

The lock pin or interlock pin is missing.

The coupling pin for the shift rod is loose or missing.

Automatic Stick Shift

Fluid leakage

The automatic transmission fluid is a deep red color. The fluid leaks should not be confused with the engine oil, which can be blown onto the transaxle by airflow really easily.

In order to pinpoint a leak, you’ll need to first remove all the built-up dirt and grime from the transaxle housing with degreasing agents and/or steam cleaning. After this, drive the vehicle at low speeds so the airflow will not blow the leak far from its source. Raise the vehicle and determine where the leak is coming from.

The transaxle fluid brown is or has a burned smell.

The transaxle fluid is burned.

Clutch slips at full throttle

There is insufficient freeplay.

The clutch linings are contaminated.

The clutch linings are worn.

Excessive clutch slippage after gear selection

There is a leaking hose between carburetor and the control valve.

The control valve filter is blocked.

The adjusting screw on the reduction valve is in too far.

Clutch is disengaging improperly

There is leaking in the vacuum hose or the vacuum tank.

There is excessive freeplay.

The servo is defective.

Clutch is not disengaging.

The solenoid circuit is open.

There is a bad ground connection between the selector lever and the frame.

The hoses to the servo are kinked or collapsed.

The servo is defective.

The engine stalls when the gear is selected.

The hose between the servo and control valve is leaking.

The engine stalls and won’t restart.

The hose between the control valve and carburetor or vacuum tank are leaking.

The clutch doesn’t engage after the gear selection.

The selector level switch is sticking.

There is a short in the solenoid circuit.

The solenoid in the control valve is sticking.

The clutch grabs after gear selection

The clutch linings are contaminated with oil.

The carrier plate is distorted.

Vehicle jerks at idle when shift lever is released.

The idle speed is too high.

The control valve is misadjusted.

Torque converter noisy (high-pitched hissing)

The ATF level is low.

The ATF pressure is low.

The converter or converter seal is leaking.

Poor acceleration (engine output satisfactory)

The one-way clutch in the torque converter is faulty.

Engine will start in gears other than Neutral

The neutral start switch is malfunctioning.

Drive axles

Shudder or vibration during acceleration

There is excessive toe-in.

The spring heights are incorrect.

The inboard or outboard is worn or damaged.

The inboard CV joint assembly is sticking.

There is vibration at highway speeds.

The front wheels and/or tires are out of balance.

The front tires are out of round.

The CV joint(s) are worn.

Brakes

Note: Before you assume that a brake problem does exist, make sure that:A) The tires are in good condition and are properly inflated.
B) The front-end alignment is correct.
C) The vehicle is not loaded with weight in an unequal manner.

Vehicle pulls to one side during braking.

The tire pressures are incorrect.

The front end is out of line (have the front end aligned).

The front or rear tires are not matched to one another.

The brake lines or hoses are restricted.

The drum brake or caliper assembly is malfunctioning.

The suspension parts are loose.

The backing plates or calipers are loose.

There is too much wear of brake shoe or pad material or disc/drum on one side.

Noise (high-pitched squeal when the brakes are applied)

The brake pads or brake shoes are worn out. You’ll want to replace pads/shoes with new ones right away.

Make sure to check the disc/drums for damage as well.

Brake roughness or chatter (pedal pulsates)

The disc lateral runout is excessive.

There is uneven pad wear.

The is a defective disc.

The drum is out-of-round.

Excessive brake pedal effort is required to stop the vehicle.

There is partial system failure.

The pads or shoes are excessively worn.

The piston in the caliper or wheel cylinder is stuck or even sluggish.

The brake pads or shoes are contaminated with oil or grease.

The new pads or shoes that were installed are not yet seated. It will take a while for the new material to seat against the rotor or drum.

Excessive brake pedal travel

There is partial brake system failure.

There is insufficient fluid in the master cylinder.

There is air trapped in the system.

The brakes are in need of adjustment.

The brakes are dragging.

The master cylinder pistons are not returning correctly.

The brake lines or hoses are restricted.

The parking brake has been incorrectly adjusted.

There is grabbing or uneven braking action

The brake pedal mechanism is binding.

There is grease or oil on the brake lining.

Brake pedal feels spongy when depressed.

There is air in the hydraulic lines.

The master cylinder mounting bolts are loose.

The master cylinder is defective.

The brake pedal travels to the floor with little resistance.

There is little or no fluid in the master cylinder reservoir caused by a leaking caliper or wheel cylinder piston(s).

The brake lines are loose, damaged or disconnected.

Parking brake does not hold.

The parking brake cable is improperly adjusted.

Suspension and steering systems

Note: Before attempting to diagnose the suspension and steering systems, perform the following preliminary checks:
a) Tires for wrong pressure and uneven wear.
b) The steering couplings from the column to the steering gear for loose connectors or wear.
c) The front and rear suspension and the steering gear assembly for loose or damaged parts.
d) Out-of-round or out-of-balance tires, bent rims and loose and/or rough wheel bearings.

Vehicle pulls to one side.

The tires are mismatched or uneven.

The torsion bars are broken or sagging.

Needs wheel alignment.

The front brakes are dragging.

Abnormal or excessive tire wear.

There is incorrect wheel alignment.

The torsion bars are sagging or broken.

The tires are out of balance.

The shock absorber or strut damper is worn.

The vehicle is overloaded.

The tires are not rotated regularly.

The wheel makes a thumping noise.

There is a blister or a bump on the tire.

There is improper shock absorber or strut damper action.

Shimmy, shake or vibration

The tire or wheel is out-of-balance or out-of-round.

The wheel bearings are loose or worn.

The tie-rod ends are worn.

The ball joints are worn.

The wheel runout is excessive.

There is a blister or bump on the tire.

Hard steering

There is a lack of lubrication at the ball joints, tie-rod ends and steering gear assembly.

The front wheel alignment is incorrect.

The tire pressure(s) is low.

There is poor returnability of steering to center.

There is a lack of lubrication at the ball joints and the tie-rod ends.

There is binding in the ball-joints.

There is binding in the steering column.

There is lack of lubricant in the steering gear.

The front wheel alignment is incorrect.

Abnormal noise at the front end

There is a lack of lubrication at the ball-joints and tie-rod ends.

The shock absorber or strut is damaged.

The control arm bushings or tie-rod ends are worn.

The stabilizer bar is loose.

The wheel lug bolts are loose.

The suspension bolts are loose.

Wander or poor steering stability

The tires are mismatched or uneven.

There is a lack of lubrication at the ball-joints and tie-rod ends.

The shock absorbers or strut assemblies are worn.

The stabilizer bar is loose.

The torsion bars are broken or sagging.

The wheel alignment is incorrect.

The steering is erratic when braking.

The wheel bearings are worn or out of adjustment.

The torsion bars are broken or sagging.

The wheel cylinder or caliper is leaking.

The discs or drums are warped.

There is excessive pitching and/or rolling around corners or during braking

The stabilizer bar is loose.

The shock absorbers or strut dampers are worn.

The torsion bars are broken or sagging.

The vehicle is overloaded.

The suspension bottoms

The vehicle is overloaded.

The shock absorbers or strut dampers are worn.

The torsion bars are incorrect, broken or sagging.

Cupped tires

The front wheel or rear wheel alignment is incorrect.

The strut dampers or shock absorbers are worn.

The wheel bearings are worn.

There is excessive tire or wheel run-out.

The ball-joints are worn.

Excessive tire wear on outside edge

The inflation pressures are incorrect.

There is excessive speed in turns.

The front-end alignment is incorrect. Have it professionally aligned.

Excessive tire wear on inside edge

The inflation pressures are incorrect.

The front-end alignment is incorrect. Have it professionally aligned.

Tire tread is worn in one place.

The tires are out of balance.

The wheel is damaged or buckled. Inspect and replace if necessary.

A tire is defective.

Excessive play or looseness in steering system

The wheel bearing(s) are worn or out of adjustment.

The tie-rod end is loose.

The steering gear is loose.

The steering intermediate shaft is worn or loose.

There is rattling or a clicking noise in the steering gear.

There is insufficient or improper lubricant in the steering gear.

The steering gear attachment is loose.

There is an internal steering gear problem