engines final (exams)
Which of these is a typical connecting rod bearing clearance? .0015" (.038mm) .0150" (.381mm) .1500" (3.810 mm) 1.500" (38.100mm)
.0015" (.038mm)
In a typical four-cylinder engine, which cylinders are paired together by their position on the crankshaft?
1 and 4, 2 and 3
Valve face and valve seat reconditioning is being discussed. Technician A says that when an interference angle is used, the valve and the seat are machined at slightly different angles. Technician B says that as the valve seat is cut, the valve stem height decreases causing valve spring seat pressure to increase. Who is correct?
A ONLY
Technician A says a typical V-8 engine has 5 main bearings. Technician B says that a typical V-8 engine has eight rod journals located 45 degrees apart. Who is correct?
A and B
A car is towed into a shop because of a cranks but will not start condition. While cranking the engine, the engine spins faster than normal and backfires in the intake manifold and exhaust. Technician A says that the engine may have jumped out of camshaft timing. Technician B says that the timing gears may have too much backlash. Who is correct?
A only
Main bearings are being installed in an engine with the marking 010 US on the back of the bearing. Technician A says that the bearings are made to be used with a crankshaft that has been ground .010 undersized. Technician B says that the US on the bearings means the bearings were made in the US. Who is correct?
A only
Technician A says crankshafts can often be straightened if warped. Technician B says cracked crankshafts can be welded and reused. Who is correct?
A only
Technician A says some VVT system change both the intake and exhaust valve timing. Technician B says a VVT system will advance valve timing and reduce valve overlap to increase power at high RPMs. Who is correct?
A only
Technician A says that bearings have a soft surface that flows away from high spots, in case of a nick in the crank. Technician B says dirt will be absorbed into the crankshaft journal surface. Who is correct?
A only
Technician A says that engine block cylinders are measured for taper. Technician B says that the piston rings typically cause the most wear in the middle of the cylinder. Who is correct?
A only
Technician A says that engine performance is enhanced at upper rpm when cam timing is retarded. Technician B says that more valve overlap creates a smooth idle. Who is correct?
A only
Technician A says that micrometers used in conjunction with a small hole gauge can be used to obtain a valve guide to valve stem measurement. Technician B says that a typical valve stem to guide clearance would be 0.01". Who is correct?
A only
Technician A says that that most gasoline engines use three piston rings per cylinder. Technician B says that the middle ring usually suffers more wear that the other rings. Who is correct?
A only
Technician A says that valve springs should be checked for squareness and pressure. Technician B says that seat pressure is measured with the spring compressed to the same height it would be when installed and the valve fully open. Who is correct?
A only
Technician A says that worn valve guides can cause valves to burn. Technician B says that stem necking is caused by worn valve guides. Who is correct?
A only
While discussing micrometer measurements, Technician A says that the vernier scale on a micrometer accurately measures down to 0.0001 inch. Technician B says that the Vernier scale on a metric micrometer reads accurately down to 0.0001 mm. Who is correct?
A only
When an engine is bored oversized during an engine rebuild, what is affected? a. Piston size b. Stroke c. Compression ratio d. All of the above
A. Piston size
A block that is to be re-used should be checked for which of the following: Deck for warpage Main bearing bore alignment Cylinder taper Cylinder out-of-round all of the above
All of the above
Timing chains are being discussed. Technician A says that timing chains must be changed in accordance with the manufacturer's maintenance schedule. Technician B says that rotating the crankshaft without camshaft movement while the engine is still together can indicate the amount of wear. Who is correct?
B ONLY
An engine has excessive main bearing oil clearance. Technician A says this can cause excessive oil consumption. Technician B says this will cause a low oil pressure. Who is correct?
B only
Technician A says crankshafts in high performance engines are generally cast iron. Technician B says crankshafts in high performance engines may be forged iron. Who is correct?
B only
Technician A says that main bearing caps are interchangeable. Technician B says that main bearing bores are checked for alignment with a straightedge and feeler gauge. Who is correct?
B only
Technician A says that piston ring end gap clearance must be less than .002" per inch of cylinder bore. Technician B says that piston ring end gap should be a minimum of .003" per inch of bore. Who is correct?
B only
Technician A says the bearing tab is used to keep the bearing from spinning in the housing bore. Technician B says the bearing tab is used to position the bearing in the housing bore. Who is correct?
B only
Technician A says upper and lower main bearings are always interchangeable. Technician B says to rotate the crankshaft after each piston and rod assembly is installed to check for problems. Who is correct?
B only
The adjustment of mechanical lifters is being discussed. Technician A says that lifters adjusted with too much clearance could result in burned valves. Technician B says that lifters adjusted with too much clearance will result in decreased valve lift and duration. Who is correct?
B only
The diameter of a piston is 3.9985", and the diameter of the cylinder is 4.000" in an engine where the manufacturer's specs for piston clearance is .0010" to .0015" Technician A says that the piston will be too loose in the cylinder bore. Technician B says that this piston is within specification for this bore. Who is correct?
B only
Warpage is being measured on the mating surface cylinder head around the edges and across the center. Technician A says that 0.030" (0.762mm) warpage is generally acceptable. Technician B says that if the warpage is excessive, the engine was most likely overheated. Who is correct?
B only
When boring a block to size, Technician A says .030" oversize pistons will measure .030". Technician B says the .030" should be the finish size of the bore. Who is correct?
B only
While discussing crankshafts, Technician A says that cast crankshafts have a thick parting line. Technician B says that when tapping a cast crankshaft with a metal object, a dull metallic sound will be heard. Who is correct?
B only
Technician A says compression ratio is based only on the distance the piston moves from BDC to TDC. Technician B says increasing the compression ratio of an engine can lead to detonation. Who is correct?
B. only
A cylinder head is being reassembled after having the valve face and valve seat resurfaced. Technician A says that this will increase the valve stem height thus decreasing spring seat pressure. Technician B says that a shim within the size recommendation of the manufacturer may be installed under the spring to correct spring seat pressure. Who is correct?
Both A and B
An engine has a burned thrust bearing. Technician A says this can be caused by a driver who "rides" the clutch on a vehicle equipped with a manual transmission. Technician B says this can be caused by a ballooning torque converter in a vehicle equipped with an automatic transmission. Who is correct?
Both A and B
Engines like the ones we are rebuilding in lab, use a main bearing "bridge" assembly (sometimes referred to as a bedplate). Technician A says that the bridge assembly connects all the main bearing caps together. Technician B says that the bridge assembly adds rigidity to the bottom end of the engine. Who is correct?
Both A and B
Technician A says a block that has spun a bearing can be align honed. Technician B says a block that has spun a bearing can be align bored. Who is correct?
Both A and B
Technician A says a small-hole gauge is used with an outside micrometer. Technician B says the small-hole gauge is used on valve guides. Who is correct?
Both A and B
Technician A says if the ring has an identification mark (dot or slash) the mark should be oriented facing upward. Technician B says that installing a compression ring upside down can cause oil consumption. Technician E says that installing a ring inside out will make the car run faster, last longer and is finger lickin goooood besides. Who is correct?
Both A and B
Technician A says some piston rings have chamfers or reliefs cut into them to cause them to twist. Technician B says chrome rings should not be used in out-of-round cylinders. Who is correct?
Both A and B
Technician A says that pistons pins in press fit assemblies can be removed using a piston press. Technician B says that full-floating piston pins can be removed by hand once the retainer ring has been removed. Who is correct?
Both A and B
Technician A says that when an engine block is bored, the original pistons must be replaced. Technician B says that a cylinder that is out-of-round may be repaired by boring. Who is correct?
Both A and B
Technician A says that worn camshaft bearings cause low oil pressure. Technician B says that camshaft bearings installed in the engine block are pressed into place with a special tool. Who is correct?
Both A and B
When measuring a head for surface flatness, Technician A says that a straight edge should be used. Technician B says that feeler gauges should be used. Who is correct?
Both A and B
A customer comes into a shop with a complaint that his car is smoking. The smoke appears in a big cloud after starting and then clears up. He also notes smoking during long periods of deceleration or idling. Technician A says that the valve stem seals may be worn. Technician B says that if the valve stems seals are worn, they may be changed without removing the cylinder head.
Both A and b
All of the following can be accomplished with variable valve timing while the engine is running EXCEPT ____. a. changing valve overlap b. changing cam timing c. altering engine displacement d. improving emissions
C. altering engine displacement
Crankshaft journals are measured for all of the following EXCEPT ____. a. taper b. out-of-round c. diameter d. runout
D. runout
All of the following are true about OHV camshafts and lifters EXCEPT ____. a. lifters must always be installed on the same lobe for which it was removed b. the normal shape for the bottom of a lifter is convex c. hydraulic lifters should be tested for leak-down during inspection if they are to be reused d. used lifters can be installed on a new camshaft as long as they pump up
D.used lifters can be installed on a new camshaft as long as they pump up
You are working on a 2005 Honda Accord with a F23 2.3L engine. Three of the rod journals measure 1.9995 inches and the fourth rod journal measures 1.9970". Specifications call for 1.9990"-2.0000". What is the proper fix? Weld the journal and grind to standard Grind that journal .010" and use a .010" US bearing Grind all the rod journals .010" and use .010" OS bearings Grind all the rod journals .010" and use .010" US bearings Do I hear J-B Weld and a piece of coarse sandpaper?
Grind all the rod journals .010" and use .010" US bearings
Bearing crush is used to: Locate the bearing in the bore. Retain the bearing in the bore during assembly. Keep the bearing from spinning in the bore. All of the above None of the above
Keep the bearing from spinning in the bore.
Which is NOT a characteristic of an engine bearing?
Lubricity
Cylinder taper is being discussed. Technician A says taper does not affect the ring gap as the piston goes up and down. Technician B says that up to.010" (.254mm) is usually an acceptable amount of taper. Who is correct?
Neither A or B
Technician A says that taper is the difference between two measurements at the top of the cylinder. Technician B says that out-of-round is the difference between a measurement at the top of the cylinder and a measurement at the bottom of the cylinder. Who is correct?
Neither A or B
Technician A says that the barrel of an inside micrometer has a range of 1 inch without any special adapters. Technician B says that a depth micrometer reads left to right exactly like an outside micrometer. Who is correct?
Neither A or B
Technician A says that when a long block is purchased, the old cylinder heads must be reused. Technician B says that a long block includes the cylinder heads, intake and exhaust manifolds. Who is correct?
Neither A or B
Bearing spread is used to: Locate the bearing in the bore. Retain the bearing in the bore during assembly. Keep the bearing from spinning in the bore. All of the above None of the above
Retain the bearing in the bore during assembly.
Hypereutectic pistons refer to: The casting process The forging process The piston head design The silicon content
The silicon content
The torque specification for a valve cover gasket is 5 foot-pounds. Which of the following is the best procedure?
Use an inch-pound torque wrench and torque to 60 inch-pounds.
Technician A says some valve guides must installed into the cylinder head using a press. Technician B says many newer engines use threaded valve guide inserts. Who is correct?
a only
All of the following would immediately rule out the reuse of a valve EXCEPT ____. a. excessive carbon deposits b. burned face c. non-visible margin d. bent stem
a. excessive carbon deposits
All of the following are part of cylinder reconditioning EXCEPT ____. a. resurfacing b. sleeving c. honing d. boring
a. resurfacing
Load on a bearing can come from: Pressure from the flame front against the piston Centrifugal force of the rod and crankpin Inertia from the piston and rod assembly all of the above
all of the above
Which of the following can be caused by a separated harmonic balancer? a. Engine failure b. Vibration c. Crankshaft damage
all of the above
All of the following are crankshaft repairs EXCEPT ____. a. grinding b. crack welding c. polishing d. straightening
b crank welding
Technician A says that a camshaft must make two full rotations for the crankshaft to make one. Technician B says that the crankshaft pulley has half the number of teeth than the camshaft. Who is correct?
b only
Technician A says that hydraulic lifters are adjusted when the valves are open so that the plunger may be put into a centered position. Technician B says that solid lifters require adjustment over time as engine parts wear. Who is correct?
b only
Technician A says that improper valve timing cannot affect cylinder compression. Technician B says that a timing belt that is off by one tooth will not affect valve lift. Who is correct?
b only
Technician A says that timing components are built with a tolerance that allows + or - one tooth to be aligned improperly during installation. Technician B says that water pumps can be driven by the timing belt or the timing chain on some engines. Who is correct?
b only
Technician A says that valve spring free height is checked with the spring installed and under pressure. Technician B says that valve spring coil bind can cause bent pushrods. Who is correct?
b only
Technician A says that a warpage of 0.300" (7.62mm) is acceptable for most pushrods. Technician B says that some pushrods are hollow in design to oil valvetrain components. Who is correct?
b onyl
50 pounds applied to a wrench 24 inches long will produce how much torque: a. 250 ft lbs b. 100 ft lbs c. 150 ft lbs d. 50 ft lbs
b. 100 ft lbs
Technician A says that flat bottomed lifters spin in the lifter bore due to the shape of the camshaft lobes. Technician B says that roller lifters require a roller-type camshaft. Who is correct?
both A and B
Technician A says that the clearance between the valve guide and valve stem should be checked before grinding valve seats. Technician B says that valve seats may be removed and replaced on some cylinder heads. Who is correct?
both A and B
Technician A says that valve lash can be adjusted on a cylinder that is at TDC and on the compression stroke. Technician B says that feeler gauges are used when adjusting solid lifters. Who is correct?
both A and B
Technician A says that worn valve guides can cause excess oil consumption. Technician B says that valve guide to valve stem clearance can be measured using a dial indicator. Who is correct?
both A and B
Technician A says that worn valve stem seals will affect oil consumption. Technician B says that valve stem seals should be replaced when performing an engine overhaul. Who is correct?
both A and B
Technician A says the PCM controls oil pressure to the cam phasers to advance or retard valve timing. Technician B says that some variable valve timing systems can change valve lift and duration. Who is correct?
both A and B
Timing belts are being discussed. Technician A says that a timing belt should be replaced in accordance with the manufacturer's maintenance schedule. Technician B says that timing belts that are adjusted too tight may whine.
both A and B
A vehicle with an OHC driven by chain and sprockets is brought into a shop for a noise. While running, a slapping sound is heard from the timing cover. Technician A says that the timing chain may be hitting the cover and this should be addressed right away. Technician B says that timing chain looseness can be determined by measuring how far the crankshaft will turn before the camshaft turns. Who is correct?
both A and b
Technician A says that valve stem height is measured from the valve spring seat to the valve stem tip. Technician B says that incorrect valve stem height can cause valve spring seat pressure to be below specification. Who is correct?
both A and b
Technician A says that it is possible to replace press-in type rocker arm studs with threaded ones by milling, then using a tap to thread the boss in the head. Technician B says that it is good practice to replace stamped steel rocker arms during an overhaul. Who is correct?
both a and b
Which of the following are common cylinder arrangements? a. V-blocks b. Opposed c. Inline d. All of the above
d. All of the above
A feeler gauge is needed to check
gap between two parts
In many displacement-on-demand engines, the PCM controls cylinder deactivation by using specially controlled:
lifters
What does the process of line boring address?
main bearing saddle problems
Technician A says balance shafts are used to reduce the vibrations produced when the pistons are at TDC and BDC. Technician B says balance shafts rotate at crankshaft speed. Who is correct?
neither
Technician A says that resurfacing the deck of a block is usually done in an automotive repair shop. Technician B says that sleeves are installed after the block deck is resurfaced. Who is correct?
neither A or B
Two technicians are discussing camshafts.Technician A says that increased valve overlap is caused by camshaft lobe wear. Technician B says worn camshaft lobe wear will cause burnt valves. Who is correct?
neither A or B
Valve inspection is being discussed. Technician A says that valve margins are only necessary on exhaust valves. Technician B says that a valve with bent stems can be repaired using a valve grinding machine. Who is correct?
neither A or B
If a micrometer spindle must be moved a long way to adjust it, roll the ____ on your arm or hand.
thimble
The purpose of a chamfer on a cylinder is:
to aid in piston and ring installation