ASE Automobile (A1–A8) — All Questions

A cylinder head is warped beyond specification. Which service is normally required to restore a flat sealing surface?

• a.Retorquing the head while hot
• b.Replacing the head bolts only
• c.Resurfacing (machining) the head✓
• d.Installing a thicker head gasket

A warped head must be resurfaced by machining to bring the deck within flatness specification. A thicker gasket will not correct an uneven surface, and simply retorquing does not remove the warp. Excessive material removal, however, can raise compression and change valve timing on some engines.

Technician A says a blown head gasket can allow coolant to enter a cylinder and cause white exhaust smoke. Technician B says it can cause bubbles in the coolant recovery tank from combustion gases. Who is correct?

• a.Technician A only
• b.Technician B only
• c.Both A and B✓
• d.Neither A nor B

A failed head gasket can leak both ways: coolant into the cylinder produces white steam-like exhaust, and combustion pressure into the cooling system produces bubbles and possible overheating. Both technicians describe valid symptoms. A cooling-system pressure test and a combustion-gas (block) test help confirm the diagnosis.

A valve that fails to seat fully will most directly cause which condition?

• a.High oil pressure
• b.Low cylinder compression on that cylinder✓
• c.Excessive oil consumption only
• d.A stuck lifter

A valve that does not seat allows combustion pressure to escape, lowering compression in that cylinder and often causing a misfire. A cylinder leak-down test with air hissing from the intake or exhaust confirms an intake or exhaust valve leak. Burned valves and carbon deposits are common causes.

On an overhead-cam engine, excessive valve lash (clearance) most commonly produces which symptom?

• a.Low oil pressure
• b.A clicking or tapping noise from the valvetrain✓
• c.Blue exhaust smoke
• d.Loss of coolant

Too much clearance in the valvetrain lets components hammer against one another, producing a rhythmic tapping that changes with engine speed. Insufficient lash, by contrast, can hold valves open and burn them. Proper adjustment restores quiet operation and correct valve timing.

Technician A says the PCV system routes crankcase blow-by vapors into the intake to be burned. Technician B says a stuck PCV valve can cause rough idle or oil leaks. Who is correct?

• a.Technician B only
• b.Both A and B✓
• c.Technician A only
• d.Neither A nor B

The PCV system draws blow-by gases into the intake so they are burned rather than vented, and a stuck valve can cause rough idle, oil leaks, or high oil consumption. Both technicians are correct. This reduces sludge formation and emissions.

A mechanic measures cylinder taper by comparing bore diameter at the top of ring travel to the bottom. This measurement is taken with a:

• a.Feeler gauge
• b.Compression tester
• c.Dial bore gauge or inside micrometer✓
• d.Vacuum gauge

Cylinder taper and out-of-round are measured with a dial bore gauge or inside micrometer at several points in the bore. Wear is greatest at the top of ring travel where combustion heat and pressure are highest. Excessive taper requires boring and oversize pistons.

Technician A says low oil pressure only at idle on a high-mileage engine can be caused by worn bearing clearances. Technician B says a worn oil pump or diluted oil can also lower pressure. Who is correct?

• a.Both A and B✓
• b.Technician A only
• c.Technician B only
• d.Neither A nor B

Worn bearing clearances let oil escape faster than the pump maintains pressure at low speed, and a worn pump or fuel-diluted oil reduces pressure as well. Both technicians are correct. Verify with a mechanical gauge before condemning parts.

Which cooling-system component regulates coolant flow based on engine temperature?

• a.Heater core
• b.Radiator cap
• c.Thermostat✓
• d.Water pump

The thermostat stays closed until the engine reaches operating temperature, then opens to allow coolant to circulate through the radiator. A stuck-closed thermostat causes overheating; a stuck-open one causes slow warm-up and poor heater output. It is a common, inexpensive cause of temperature complaints.

A radiator pressure cap raises the system's boiling point primarily because:

• a.It adds antifreeze to the coolant
• b.It lowers the coolant level
• c.It speeds up the water pump
• d.Increased pressure raises the coolant's boiling temperature✓

Sealing the system under pressure raises the boiling point of the coolant, allowing higher operating temperatures without boil-over. A weak or faulty cap lowers the effective boiling point and can cause coolant loss. Caps should be pressure-tested when overheating is suspected.

Blue smoke from the exhaust under acceleration most often indicates:

• a.A lean misfire
• b.A rich fuel mixture
• c.Coolant in the combustion chamber
• d.Oil entering the combustion chamber✓

Blue smoke indicates oil is being burned, commonly from worn rings, cylinder walls, or valve guide seals. White smoke suggests coolant, and black smoke suggests excess fuel. A leak-down or compression test helps localize the source.

Technician A says timing-chain stretch can retard valve timing and set a camshaft/crankshaft correlation code. Technician B says a stretched timing chain has no effect on engine performance. Who is correct?

• a.Both A and B
• b.Technician B only
• c.Neither A nor B
• d.Technician A only✓

A stretched or worn timing chain changes the relationship between crankshaft and camshaft position, retarding valve timing and often setting a correlation DTC. This can cause rough running and reduced power. Technician B is incorrect because timing is directly affected.

Head bolts that use a torque-to-yield (TTY) design should be:

• a.Coated with anti-seize before reuse
• b.Replaced with new bolts during reassembly✓
• c.Reused indefinitely
• d.Torqued to half the final value only

Torque-to-yield bolts are stretched into their plastic range for a uniform clamp load and should not be reused. Reusing them risks uneven clamping and gasket failure. Always follow the specified torque-plus-angle sequence with new bolts.

The main function of engine oil, besides lubrication, includes all of the following EXCEPT:

• a.Generating spark for combustion✓
• b.Cleaning and suspending contaminants
• c.Sealing between rings and cylinder walls
• d.Cooling internal components

Engine oil lubricates, cools, cleans, and helps seal the rings, but it plays no role in generating spark. Spark is produced by the ignition system. Detergent and dispersant additives keep contaminants suspended until the filter or an oil change removes them.

A rhythmic knocking noise that is loudest under load and disappears when one cylinder is disabled most likely indicates:

• a.A loose accessory belt
• b.A worn connecting-rod bearing on that cylinder✓
• c.A sticking valve
• d.An exhaust leak

A rod bearing knock is load-sensitive and typically quiets when that cylinder's contribution is removed by disabling its injector or spark. Loose belts and exhaust leaks make different noises unrelated to individual cylinders. Excessive rod bearing clearance is confirmed with Plastigage during disassembly.

Coolant is leaking internally and the engine oil appears milky. The MOST likely cause is:

• a.A worn timing belt
• b.A failed head gasket or cracked block/head✓
• c.A clogged air filter
• d.A stuck thermostat

A milky, tan appearance in the oil indicates coolant contamination, commonly from a head gasket failure or a crack that connects a coolant passage to the oil. Continued operation damages bearings. Pressure and combustion-gas testing help pinpoint the leak path.

Before final assembly, plastigage is used to measure:

• a.Piston ring end gap
• b.Valve spring free length
• c.Bearing oil clearance✓
• d.Cylinder bore taper

Plastigage is a crushable plastic thread that indicates bearing oil clearance when compared to a scale after the cap is torqued. Ring end gap is measured with a feeler gauge in the bore, and bore taper with a bore gauge. Correct clearance is essential for oil film and bearing life.

A valve spring is checked for squareness and free length. A spring shorter than spec or leaning against a square should be:

• a.Reinstalled as-is because free length rarely affects performance
• b.Replaced, because it has lost tension and may allow valve float✓
• c.Restored by heating the spring and re-tempering the metal
• d.Corrected by installing a thicker retainer and keeper set

A spring that has lost free length or is no longer square has weakened and can allow valve float at high rpm, so it must be replaced. Weak springs cause power loss and can let valves bounce off their seats. Both free length and load-at-height are compared to specification.

Blue smoke on startup that clears after a few seconds, with good compression, most often points to:

• a.A stuck-open thermostat that keeps the engine running cold
• b.A leaking fuel injector that floods the cylinder with fuel
• c.A cracked cylinder block allowing coolant into a cylinder
• d.Worn valve stem seals or valve guides letting oil seep in✓

Oil that seeps past worn valve guide seals while the engine sits gets burned at startup, producing brief blue smoke that clears as the guides drain. Compression stays normal because the rings are still sealing. Replacing the valve stem seals usually corrects it.

During a compression test, a low cylinder rises noticeably after squirting oil into it. This indicates the cause is:

• a.A burned or leaking valve that oil cannot seal at all
• b.A cracked piston crown venting compression to the crankcase
• c.A blown head gasket letting pressure escape to coolant
• d.Worn piston rings or cylinder walls that oil temporarily seals✓

Oil temporarily seals worn rings, so a reading that jumps up on the wet test points to ring or cylinder wear rather than a valve. If the reading stays low wet, the leak is at a valve or head gasket. This wet/dry comparison localizes the cause before teardown.

During a cylinder leak-down test, air escapes from the radiator or coolant reservoir. This indicates a leak at the:

• a.Exhaust valve, heard as air hissing from the tailpipe
• b.Head gasket or a cracked head or block✓
• c.Piston rings, heard as air escaping from the oil filler
• d.Intake valve, heard as air hissing from the throttle body

Air heard bubbling in the cooling system during leak-down means combustion pressure is reaching a coolant passage, pointing to a failed head gasket or crack. Air from the intake indicates an intake valve, from the exhaust an exhaust valve, and from the oil filler indicates rings. Where the air escapes tells you where the leak is.

One cylinder is weak and a worn camshaft lobe is suspected. Lobe wear reduces that cylinder's power because it:

• a.Increases oil pressure delivered to that one cylinder head
• b.Raises the compression ratio far above the other cylinders
• c.Decreases valve lift and duration on that cylinder✓
• d.Advances the ignition timing only on the affected cylinder

A rounded-off cam lobe opens its valve less far and for less time, reducing airflow and power on that cylinder. Flat-tappet cams are especially prone to lobe wear. Measuring valve lift at the retainer or comparing lobes confirms it.

Technician A says a noisy hydraulic lifter can be caused by low oil pressure or aerated oil. Technician B says a collapsed lifter can hold a valve open and cause a misfire. Who is correct?

• a.Technician B only
• b.Technician A only
• c.Neither A nor B
• d.Both A and B✓

Hydraulic lifters rely on clean, pressurized oil, so low pressure or air makes them clatter, and a lifter that bleeds down can affect valve action and cause a misfire. Both technicians are correct. Clean oil at the correct level and pressure keeps lifters quiet.

When installing a cylinder head, the head bolts should be tightened:

• a.Only by feel with an impact gun rather than a torque wrench
• b.From one corner straight across to the opposite corner in a single pass
• c.To full final torque in random order to save time on the job
• d.Gradually in the specified sequence, usually center outward✓

Tightening in the manufacturer's sequence, typically working outward from the center in stages, distributes clamp load evenly and prevents warping the head or crushing the gasket. Skipping the sequence causes leaks. Many heads use a torque-plus-angle procedure with new bolts.

An engine overheats only at idle or in slow traffic but cools at highway speed. The MOST likely cause is:

• a.A stuck-closed thermostat that blocks flow at all engine speeds
• b.A worn timing chain that has retarded the engine's valve timing
• c.An inoperative cooling fan or fan clutch✓
• d.A collapsed lower radiator hose that starves the water pump

At speed, ram air cools the radiator, but at idle the electric fan or fan clutch must move the air; if it fails, the engine overheats when stopped. A stuck thermostat overheats at all speeds. Verifying fan operation is the first check for this pattern.

Coolant dripping from the weep hole under the water pump, with a bearing whine, indicates:

• a.A failing water pump seal and bearing✓
• b.A cracked overflow bottle slowly losing coolant onto the ground
• c.A bad radiator cap venting coolant into the overflow reservoir
• d.A leaking heater core dripping coolant inside the passenger cabin

The weep hole is designed to leak when the internal pump seal fails, protecting the bearing from coolant; leakage plus noise means the pump is worn out. Continued use risks pump seizure and belt or timing damage. Replacing the pump and inspecting the belt corrects it.

A serpentine belt that squeals on acceleration and shows a glazed underside most likely needs:

• a.A permanent coating of belt dressing to quiet the squealing noise
• b.A belt one size wider than specified to grip the pulleys better
• c.The tensioner removed entirely so the belt can run more freely
• d.A new belt plus inspection of the automatic tensioner✓

Glazing and squeal indicate belt wear or a weak tensioner that no longer maintains proper tension, so the belt should be replaced and the tensioner checked. A worn tensioner spring lets the belt slip. Belt dressing only masks the problem temporarily.

A 50/50 mix of antifreeze and water is used instead of straight antifreeze mainly because the mix provides:

• a.Extra lubrication for the water pump as its single main purpose
• b.A higher freezing point than a mixture that contains added water
• c.Better heat transfer with freeze and boil protection✓
• d.A lower material cost, which is the only reason it is specified

Water transfers heat better than pure antifreeze, so a balanced mix cools effectively while still protecting against freezing, boiling, and corrosion. Straight antifreeze actually transfers heat poorly and can raise operating temperature. The correct ratio and coolant type matter for protection.

All of the following can cause an engine to overheat EXCEPT:

• a.A thermostat stuck closed that will not let coolant circulate
• b.A low coolant level or an airlock trapped in the cooling system
• c.A radiator restricted or clogged with scale, debris, or bugs
• d.An overcharged air conditioning refrigerant system✓

Overheating comes from anything that blocks heat rejection or coolant flow, such as a stuck thermostat, low coolant, or a clogged radiator; an A/C overcharge does not directly overheat the engine coolant. Diagnosis follows coolant flow and airflow. The A/C system is a separate refrigerant circuit.

The bypass valve built into or around an oil filter is designed to:

• a.Drain oil out of the filter whenever the engine is shut off and cools
• b.Increase oil pressure permanently once the engine reaches operating speed
• c.Regulate engine coolant temperature by routing warm oil to the cooler
• d.Let oil bypass a clogged filter so parts still get oil✓

If the filter media becomes plugged, the bypass valve opens so unfiltered oil still reaches the bearings rather than starving them. Dirty oil is better than none for short-term protection. Regular oil changes prevent the filter from clogging in the first place.

In the oil rating 5W-30, the '5W' refers to the oil's:

• a.Detergent and dispersant strength rating measured under high heat
• b.Percentage of the total additive package blended into the base oil
• c.Cold-temperature (winter) flow characteristics✓
• d.Operating oil pressure the engine develops at its normal idle speed

In a multi-viscosity oil, the number before the W describes flow when cold for easier starting, while the second number describes viscosity at operating temperature. A lower W number flows better in the cold. Using the specified grade protects the engine across the temperature range.

Crankshaft endplay is measured with a dial indicator by prying the crank fore and aft. Excessive endplay indicates a worn:

• a.Main bearing whose vertical oil clearance has opened up with wear
• b.Thrust bearing✓
• c.Camshaft bearing that no longer supports the cam journals properly
• d.Connecting-rod bearing that has developed too much oil clearance

The thrust bearing controls the crankshaft's front-to-back movement, so excessive endplay points to thrust bearing wear. Too much endplay can cause a knock and disturb the crank sensor or converter. It is checked with a dial indicator against the crank snout.

A deep knock present at idle that worsens with load, following recent low oil pressure, most likely indicates:

• a.A slipping accessory drive belt riding on a worn or seized pulley
• b.A worn crankshaft bearing damaged by oil starvation✓
• c.A sticking EGR valve allowing exhaust to enter the intake at idle
• d.A loose spark plug that is not fully torqued into its cylinder head

Loss of oil film from low pressure damages the crankshaft bearings, producing a load-sensitive knock. A rod bearing knock is often quieted by disabling that cylinder, while a main bearing knock is a heavier, lower thump. Confirming oil pressure and inspecting bearings is required.

When installing piston rings, the ring end gaps should be:

• a.Aligned directly over the wrist pin so the gaps share a common axis
• b.Staggered around the piston, not aligned with each other✓
• c.Positioned all together on the thrust side of the piston skirt
• d.Butted tightly together with essentially zero end-gap clearance

Staggering the end gaps keeps combustion pressure from blowing straight down through aligned gaps, reducing blow-by and oil consumption. The correct end gap clearance is also checked in the bore with a feeler gauge. Aligned gaps cause smoking and pressure loss.

A light knocking or slapping noise loudest on a cold start that quiets as the engine warms most likely indicates:

• a.A leaking head gasket letting combustion gases into the cooling system
• b.A clogged catalytic converter creating exhaust restriction under load
• c.Piston slap from excessive piston-to-wall clearance✓
• d.A worn water pump bearing that only makes noise once fully warmed

Piston slap occurs when a worn piston rocks in the bore while cold, and it quiets as the piston expands with heat. It is usually not immediately harmful but indicates cylinder wear. A cracked piston skirt can produce a similar cold noise.

A ticking noise loudest when the engine is cold that diminishes as it warms, near the exhaust, often indicates:

• a.A slipping timing chain that has begun to jump teeth on the sprocket
• b.A cracked exhaust manifold or a leaking manifold gasket✓
• c.A worn crankshaft main bearing that knocks harder as clearance grows
• d.A failing oil pump that cannot maintain pressure at operating speed

A cracked manifold or leaking gasket ticks when cold because the gap is largest before the metal expands and closes it with heat. The sound is a rhythmic exhaust tick. Inspection and a leak test confirm the crack.

A vacuum gauge on the intake shows a steady but low reading (about 12 in-Hg) at idle. This most commonly indicates:

• a.A single burned valve, which would drop the needle rhythmically
• b.Excessive oil pressure being transmitted through the intake manifold
• c.Retarded ignition or valve timing, or a vacuum leak✓
• d.A perfectly healthy engine reading well within normal specification

A steady low vacuum reading points to late timing or a general leak rather than a single-cylinder fault, which would make the needle drop rhythmically. Vacuum testing is a quick way to gauge engine condition. Comparing the pattern to known signatures guides diagnosis.

A core (freeze) plug leaking coolant on the side of the block should be:

• a.Replaced with a new plug and sealer✓
• b.Ground off flush with the block and simply left open to the air
• c.Sealed temporarily with tape and left in service until it worsens
• d.Left alone if the leak appears small and slow at the moment

A corroded or pushed-out core plug leaks coolant and must be replaced, since it is a sealed opening left from casting. Coolant loss leads to overheating. The new plug is installed with sealer and driven in squarely.

On an interference engine, a broken timing belt will most likely cause:

• a.A sudden increase in oil pressure as the camshaft stops turning
• b.A slipping clutch as the engine loses power to the drivetrain
• c.Only a simple no-start condition with no other internal damage
• d.Valve-to-piston contact and internal engine damage✓

In an interference design the valves and pistons share the same space at different times, so a broken belt lets them collide, bending valves or worse. This is why timing belts have strict replacement intervals. A non-interference engine simply stops without contact.

Valve lash adjusted too tight (too little clearance) on a solid-lifter engine can cause:

• a.Increased oil consumption from oil pulled past the valve guides
• b.A burned valve from being held slightly off its seat✓
• c.Higher oil pressure because the lifters bleed down more slowly
• d.Excessive valvetrain noise as the rocker hammers the valve tip

Too little clearance can hold a valve off its seat as the engine heats and parts expand, preventing the valve from cooling through the seat and burning it. Too much lash instead causes noise. Correct lash allows full seating and heat transfer.

Cylinder head flatness (warp) is checked with a:

• a.Compression tester threaded into each spark plug hole in turn
• b.Vacuum gauge connected to a port on the intake manifold runner
• c.Dial bore gauge set to the diameter of each cylinder in the block
• d.Straightedge and feeler gauge across the deck✓

A precision straightedge laid across the head with a feeler gauge slipped underneath reveals warp beyond the flatness limit. Excess warp requires resurfacing. This check is done in several directions across the deck.

With a rocker arm ratio of 1.6:1 and a cam lobe lift of 0.300 inch, the valve lift is approximately:

• a.1.600 inch, equal to the rocker arm ratio expressed in inches
• b.0.300 inch, the same as the measured lobe lift on the camshaft
• c.0.188 inch, found by dividing lobe lift by the rocker arm ratio
• d.0.480 inch✓

Rocker arm ratio multiplies lobe lift, so 0.300 inch times 1.6 equals 0.480 inch of valve lift. The rocker acts as a lever to increase lift at the valve. Understanding the ratio matters when comparing cam specs and valve movement.

A voltmeter with one lead in the coolant and one on the battery negative reads a high DC voltage. This indicates:

• a.A perfectly normal, healthy cooling system with fresh coolant inside
• b.Electrolysis that can corrode cooling-system metals✓
• c.A thermostat stuck closed and raising the engine's temperature
• d.A weak battery that simply needs recharging or replacement soon

Stray current through the coolant, often from a poor engine ground, creates electrolysis that eats away radiators, heater cores, and pump parts. Fresh coolant with intact inhibitors and good grounds keep it low. A high reading calls for finding the ground fault.

A chemical block tester (combustion leak test) checks for a head gasket leak by detecting combustion gases in the:

• a.Coolant, shown by a color change in the test fluid✓
• b.Intake manifold, measured as a change in idle vacuum reading
• c.Exhaust stream, measured as a rise in tailpipe backpressure
• d.Engine oil, measured by comparing hot and cold oil viscosity

The block tester draws air from the coolant reservoir through a blue fluid that turns yellow if combustion gases are present, confirming a head gasket or crack. It detects hydrocarbons that should never reach the coolant. It is a quick, non-invasive test.

Detonation (spark knock) differs from pre-ignition in that detonation is:

• a.A condition caused only by an excessively rich air-fuel mixture
• b.Uncontrolled combustion after the spark collides with the flame✓
• c.Combustion that begins before the spark plug fires from a hot spot
• d.A completely normal combustion event that occurs at every idle

Detonation is a secondary autoignition after the plug fires, whose pressure spikes collide with the normal flame and cause the knock, while pre-ignition ignites before the spark from a hot spot. Both can damage pistons. Low octane, carbon, lean mixtures, and overheating promote knock.

Thick, dark sludge found throughout an engine is most commonly the result of:

• a.Frequent long highway trips that keep the oil fully warmed up
• b.Neglected oil changes and extended drain intervals✓
• c.Installing a fresh oil filter at every scheduled service interval
• d.Using a full-synthetic oil that resists breaking down under heat

Sludge forms when oil oxidizes and collects contaminants because it was not changed on schedule, clogging passages and starving parts. Short trips and skipped services accelerate it. Regular changes with the correct oil prevent sludge.

The oil pressure relief valve in the lubrication system:

• a.Cools the oil by routing it through a heat exchanger in the pan
• b.Limits peak oil pressure by returning excess oil to the pan✓
• c.Increases oil pressure without limit as engine speed keeps rising
• d.Filters contaminants out of the oil before it reaches the bearings

The relief valve opens when pressure exceeds a set point, bleeding oil back to the sump so the system is not over-pressurized. A stuck valve can cause abnormally high or low pressure. It protects seals, the filter, and galleries.

A hiss that changes with throttle, plus a rough idle and lean fuel trims, most likely indicates:

• a.A vacuum or intake manifold gasket leak adding unmetered air✓
• b.A worn crankshaft bearing that knocks louder as engine load rises
• c.A slipping serpentine belt squealing under accessory drive load
• d.A clogged oil filter forcing oil through the filter's bypass valve

Unmetered air entering through a leaking intake or vacuum line makes a hiss and leans the mixture, roughening idle and driving fuel trims positive. Smoke testing pinpoints the leak. Sealing the leak restores idle quality.

The purpose of the crankcase ventilation (PCV) system in managing airflow is to prevent:

• a.Pressure buildup and sludge from blow-by in the crankcase✓
• b.Engine coolant from being drawn into the oil through the galleries
• c.The catalytic converter from overheating during hard acceleration
• d.The alternator from overcharging the battery at higher rpm

By drawing blow-by vapors out of the crankcase, the PCV system relieves internal pressure and reduces moisture and sludge, sending the vapors to be burned. A blocked system builds pressure that pushes out oil at seals. It also lowers emissions.

After a coolant refill, an engine has intermittent overheating and inconsistent heater output. The MOST likely cause is:

• a.A cracked cylinder head letting combustion gases into the coolant
• b.A worn oil pump unable to maintain pressure at operating speed
• c.A seized brake caliper dragging and overheating one front wheel
• d.Trapped air (an airlock) that must be bled from the system✓

Air trapped after service blocks coolant flow, causing erratic temperature and poor heat until it is purged through the bleeder or by proper fill procedure. Many engines require a specific bleeding sequence. Confirming full coolant flow resolves it.

Technician A says a straightedge check can reveal a warped intake manifold sealing surface. Technician B says an intake gasket leak can cause coolant loss or a vacuum leak. Who is correct?

• a.Technician A only
• b.Neither A nor B
• c.Both A and B✓
• d.Technician B only

A straightedge reveals a warped intake flange, and depending on design an intake gasket can leak coolant, oil, or vacuum. Both technicians are correct. The failure mode depends on which passages the gasket seals on that engine.

Technician A says excessive valve guide clearance can cause oil consumption and smoke. Technician B says worn guides can cause erratic seating and a misfire. Who is correct?

• a.Technician B only
• b.Neither A nor B
• c.Both A and B✓
• d.Technician A only

Loose guides let oil down the stems and allow the valve to wander off its seat, causing oil burning and possible misfire. Both technicians are correct. Guide and seal service restores control of the valve and oil.