Area B has 6 of the 45 scored questions, down from 10 in 2025, yet its task list is still 20 items long. Expect inspect-and-decide questions: a warped head, a seat contact out of place, a timing code right after a repair, a bolt that must not be reused.
6scored questions on the test
10in the 2025 edition
20tasks in the area
13questions on this page
What area B asks
From the 2026 task list, in our words:
Head inspection: cracks, warpage, corrosion and passages; the mating surface finish before a new gasket goes on.
Valves and seats: the condition of faces and seats.
Springs, retainers and locks: squareness, a height comparison between springs, worn lock grooves.
Guides and seals: stem-to-guide clearance; replacing valve stem seals.
Rockers, pushrods and lifters: wear, bends, cracks and blocked oil passages; valve lash and preload.
Cam drive and timing: gears, chains, tensioners, guides and belts; journals, lobes and bores; timing the camshafts to the crankshaft.
VVT and VVL components on overhead-cam engines.
Fasteners: head bolt torque by the manufacturer's procedure, damaged threads, core and gallery plugs.
New in 2026:camshaft-driven pumps (B20), such as the high-pressure fuel pump of a direct-injection engine.
Where the wrong options come from
Torque-to-yield bolts are stretched on purpose by a torque step followed by an angle step. Reuse them only if the manufacturer's procedure allows it, and follow its instructions on oiled or dry threads, since that changes the clamping force at the same torque.
Sequence: tighten head bolts in the specified order and steps, and loosen them in the reverse order on a cold engine, so neither the head nor the deck warps.
Warpage is checked with a straightedge and feeler gauge across and diagonally, then compared with the specification.
Cracks in aluminum heads call for dye penetrant or a pressure test. Magnetic particle inspection works only on iron.
Timing codes right after a head job point first to cam timing set wrong on reassembly. Check the marks before you blame a sensor or a VVT solenoid.
A timing belt job includes the tensioner and idlers, and the water pump where the belt drives it.
Seat contact is checked with marking compound after a valve job: its width and its position on the valve face both have a specification.
13 head and valve train questions
0 of 13 answered · 0 correct
Question 1 of 13 · Cylinder Head and Valve Train Diagnosis and Repair · 13%Not answered
A vehicle is towed into the shop with a blown cylinder head gasket shortly after a replacement was performed. During the diagnostic interview, the previous technician admits to thoroughly cleaning and reusing the original torque-to-yield head bolts. What is the most likely cause of the gasket failure?
Explanation
Incorrect: Thread lubrication changes clamp load, but nothing in the history points to it; the reused TTY bolts do.
Incorrect: Overtightening does crush gaskets, but the evidence here is reused bolts that clamp too weakly, not too hard.
Incorrect: A wrong sequence can warp a head, but the admitted mistake here was reusing stretched bolts.
Correct: Torque-to-yield bolts stretch permanently the first time they are tightened, so reused ones cannot clamp the gasket hard enough.
Incorrect: Coolant contamination attacks gaskets slowly, not shortly after a fresh replacement.
Question 2 of 13 · Cylinder Head and Valve Train Diagnosis and Repair · 13%Not answered
A technician finds low compression in cylinder 3. A cylinder leak-down test shows 30% leakage with air heard escaping from the intake port. A borescope inspection shows the intake valve and seat are in good condition. Which of the following is the MOST likely cause?
Explanation
Correct: With the valve and seat in good shape, lash set too tight is what holds a healthy valve slightly open and lets air out of the intake.
Incorrect: An exhaust valve spring cannot cause air to escape through the intake port.
Incorrect: A bent valve would show an uneven seat contact, and the borescope found the valve in good condition.
Incorrect: A worn guide shows up as oil use and visible wear, and the borescope found the valve seating surfaces healthy.
Incorrect: Carbon heavy enough to hold the valve open would be visible on the borescope, which showed a clean valve and seat.
Question 3 of 13 · Cylinder Head and Valve Train Diagnosis and Repair · 13%Not answered
A technician is installing cylinder head bolts that the manufacturer specifies should be installed with clean, dry threads. The technician applies engine oil to the threads. What is the most likely effect on the torque-to-yield (TTY) fastener?
Explanation
Incorrect: Less friction means more stretch at the same torque, not less clamp load.
Correct: Oil lowers thread friction, so more of the applied torque turns into stretch and the bolt clamps harder than the dry specification intends.
Incorrect: Oil does not damage threads, and the clamp load does change.
Incorrect: Oil makes the bolt turn more easily; it does not cause it to seize.
Incorrect: Thread friction is a major part of the torque reading, so changing it does change clamp load.
Question 4 of 13 · Cylinder Head and Valve Train Diagnosis and Repair · 13%Not answered
A vehicle returns with multiple camshaft position timing codes immediately after the cylinder head gaskets were replaced. The engine cranks normally but lacks power and illuminates the check engine light. What is the most likely cause of this condition?
Explanation
Incorrect: Reused head bolts threaten the gasket seal, not the camshaft timing.
Incorrect: Spark plug heat range affects plug temperature, not camshaft position relative to the crank.
Incorrect: Swapped coil wiring causes misfires, not cam-to-crank correlation codes.
Incorrect: A sealant valve cover gasket could leak oil but cannot change cam timing.
Correct: Camshaft position timing codes right after head work mean the cams were not held in time while the drive was reinstalled, which is what the OEM locking tools prevent.
Question 5 of 13 · Cylinder Head and Valve Train Diagnosis and Repair · 13%Not answered
A technician installs a cylinder head using a three-stage procedure. The manual specifies Stage 1 to 30 lb-ft, Stage 2 to 50 lb-ft, and Stage 3 to 90 degrees. The technician mistakenly performs Stage 3 by tightening the bolts to 90 lb-ft instead. What is the most likely result?
Explanation
Incorrect: Head bolt torque does not reach the timing chain.
Incorrect: Standard or not, a bolt tightened to a number other than the specified stage is not properly installed.
Incorrect: Bolts do not all snap at once; the predictable result is clamp load that differs from the design.
Correct: An angle stage is designed to give a set amount of stretch; replacing it with a torque value gives the wrong clamp load across the head.
Incorrect: Head bolt torque does not change how much the aluminum block expands with heat.
Question 6 of 13 · Cylinder Head and Valve Train Diagnosis and Repair · 13%Not answered
A cylinder head inspection reveals severely pitted valve faces and deeply recessed exhaust valve seats. After replacing the affected valves and machining the seats, which additional system should be thoroughly tested to prevent a recurring failure?
Explanation
Incorrect: A secondary air check valve protects the air pump from exhaust and does not raise combustion temperature.
Incorrect: PCV problems cause oil and sludge issues, not burned exhaust valves.
Incorrect: An EVAP purge fault affects vapor recovery and fuel trim, not valve seat temperature.
Correct: Burned valve faces and sunken seats come from very hot combustion, and a weak cooling system or poor EGR flow is what keeps it running hot.
Incorrect: VVT oil control changes valve timing but does not overheat valves and seats.
Question 7 of 13 · Cylinder Head and Valve Train Diagnosis and Repair · 13%Not answered
After a valve job, a technician checks the contact pattern with marking compound. The pattern is too narrow and located near the outer edge of the valve face, while the specification calls for a wider contact centered on the face. What should the technician do?
Explanation
Incorrect: Lapping only polishes the existing contact; it does not move it or change its width.
Incorrect: The problem is where the valve touches, not the margin, so replacing the valve does not fix it.
Correct: Contact position is set by cutting the seat with correcting angles; a narrow ring near the outer edge is moved by reshaping the seat.
Incorrect: Grinding the face removes metal and thins the margin; it does not move the contact band.
Incorrect: A thinner seat insert is a machining choice that does not by itself center the contact.
Question 8 of 13 · Cylinder Head and Valve Train Diagnosis and Repair · 13%Not answered
A service manual specifies tightening a cylinder head bolt to an initial 30 ft-lb, then an additional 90 degrees of rotation. The technician has a torque wrench calibrated in Newton-meters (Nm) and an angle gauge. Which setting should the technician use to correctly reproduce the initial torque?
Explanation
Incorrect: The initial torque stage still needs a torque wrench; only the angle stage uses the gauge.
Incorrect: The angle is independent of the wrench's units, so it should stay at 90 degrees.
Incorrect: Setting 30 on an Nm wrench gives only about 22 ft-lb, well under the specified initial torque.
Incorrect: 41 is the Nm figure; putting it in ft-lb overtightens the first stage by more than a third.
Correct: 30 ft-lb times 1.356 is about 41 Nm, and the angle stage stays at 90 degrees because angle does not depend on the wrench's units.
Question 9 of 13 · Cylinder Head and Valve Train Diagnosis and Repair · 13%Not answered
A customer complains of a persistent ticking noise from the upper engine area. Disassembly reveals severely worn camshaft lobes and lifters. The maintenance history shows oil changes were frequently missed, resulting in heavily contaminated oil. Which mechanism directly caused this specific valvetrain component damage?
Explanation
Correct: Neglected oil turns into abrasive sludge, which grinds away the highly loaded lobe and lifter faces.
Incorrect: Fuel dilution thins oil, but the history here is missed oil changes and dirty oil.
Incorrect: Coolant contamination would show as milky oil, and nothing in the history points to a coolant leak.
Incorrect: A tensioner failure affects chain or belt drive, not lobe-and-lifter wear.
Incorrect: Oil pressure does not bind lifters, and dirty oil does not raise pressure enough to do so.
Question 10 of 13 · Cylinder Head and Valve Train Diagnosis and Repair · 13%Not answered
When replacing a timing belt, what other component should typically be replaced?
Explanation
Correct: The tensioner keeps the new belt at the right tension, and a worn bearing in it can destroy the new belt, so it is replaced with the belt.
Incorrect: Spark plugs are not part of the timing drive.
Incorrect: The thermostat is not driven by or connected to the timing belt.
Incorrect: The oil filter is ordinary maintenance and has nothing to do with the timing belt job.
Question 11 of 13 · Cylinder Head and Valve Train Diagnosis and Repair · 13%Not answered
What causes a rattling noise at startup that disappears after a few seconds?
Explanation
Incorrect: A starter problem makes noise while cranking, not after the engine has started.
Correct: A slack chain slaps against its guides until oil pressure pumps up the hydraulic tensioner, so the rattle fades after a few seconds.
Incorrect: Worn main bearings knock deeply and keep knocking after oil pressure builds.
Incorrect: Low oil level makes valve train noise that continues while the engine runs, not just for a few seconds.
Question 12 of 13 · Cylinder Head and Valve Train Diagnosis and Repair · 13%Not answered
Which of the following methods is most appropriate for detecting hairline cracks in an aluminum cylinder head?
Explanation
Incorrect: A magnifying glass misses cracks too fine to see, which are the ones being looked for.
Incorrect: Tapping and listening for tone changes is not reliable on an aluminum head.
Incorrect: A dial indicator measures runout or flatness, not cracks.
Correct: Plugging the passages, pressurizing the head and submerging it makes bubbles rise from even a hairline crack.
Question 13 of 13 · Cylinder Head and Valve Train Diagnosis and Repair · 13%Not answered
When preparing a cylinder head gasket surface, what should be done after using a scraper to remove the old gasket material?
Explanation
Incorrect: A wire wheel scratches and rounds off the gasket surface.
Incorrect: Leftover residue under a new gasket creates leak paths.
Incorrect: Coarse 80-grit paper gouges the surface and ruins the finish the gasket needs.
Correct: A non-abrasive pad and solvent removes residue without cutting into the soft aluminum sealing surface.
Answer every question to see your score
Smaller, not gone
With 6 questions, area B is now the fourth of five by size. The measuring work shrank (valve spring installed height is out), but lash, timing and VVT stay, and they show up in diagnosis questions too: a stretched chain gives low compression on every cylinder. See reading engine test results.
How many A1 questions are on the cylinder head and valve train?
6 of the 45 scored questions in 2026, against 10 in the 2025 edition.
Can torque-to-yield head bolts be reused?
Only if the manufacturer's procedure says so. They are tightened past their elastic limit, so a reused bolt may stretch further and lose clamping force.
How do you check a cylinder head for warpage?
Lay a precision straightedge along, across and diagonally over the clean deck surface and slide a feeler gauge under it. Compare the largest gap with the manufacturer's limit.