Engines - Frames, Blocks, and Cylinders Flashcards
True or false:
Engine cylinders may be cast into the block or may be removable.
true
This engine component maintains all moving parts in proper relative position to each other and encloses the crankshaft and camshaft.
the engine block
What is the most common type of engine block?
the one-piece block
What is another name for a one-piece engine block?
en-block
How are the bearing caps arranged on a one-piece engine block?
underslung;
the bearing caps are under the crankshaft
What does it mean when an engine has an underslung crankshaft?
the main bearings caps are under the crankshaft;
the crankshaft is bolted to the bottom the engine block
*seen in en-block engines
What is the main advantage of a one-piece engine block when compared to a multi-piece?
rigidity;
the one piece is much more rigid
True or false:
A one-piece engine block is most often used in medium- and high-speed engines.
true
What type of engine speeds are usually found with en-block engines?
medium and high speed engines
True or false:
Multi-piece engine blocks are common in the larger low- and medium-speed engines with bores that are approximately 10” and larger.
true
What type of engine speeds are usually found with multi-piece engine blocks?
low and medium speed engines
How are the main bearing caps arranged in multi-piece engine blocks?
overslung;
the bearing caps are on top of the crankshaft
What does it mean when an engine has an overslung crankshaft?
the bearing caps are on top of the crankshaft
In an en-block engine, what does the crankshaft bolt to?
the engine block
In a multi-piece engine block, what does the crankshaft bolt to?
to the engine bedplate
What are the two pieces of a two-piece engine block and what is their purpose?
- bedplate ⟶ holds the crankshaft
- block ⟶ houses the cylinders
What are the three pieces of a three-piece engine block and what is their purpose?
- bed ⟶ holds the crankshaft
- block ⟶ location to bolt the cylinders to
- cylinders ⟶ self-explanatory
What are the two types of multi-piece engine blocks?
- two-piece blocks
- three-piece blocks
Why are the beds of three-piece engine blocks ribbed?
to form a very rigid structure
Why is the installation and mounting of the bed plate to the foundation critical with three-piece engine blocks?
if not true, the bedplate can become distorted, which will distort the crankshaft line bore;
this determine how straight the crankshaft lies in the engine, which determines bearing and crankshaft life
This type of three-piece engine inspection door has a large, spring loaded relief valve that can pop open in the event of an explosion in the crankcase, preventing damage to the block.
explosion proof inspection doors
What two tools are used to check for flatness of a cylinder block deck on an engine?
- straight edge
- feeler gauges
When pressurizing an engine block to check for coolant leaks, what is the maximum pressure that should be used?
45 psi;
anything higher could create new leak paths
During an engine inspection, the bottom liner bore where the O-ring of the liner seal sits appears to have some pitting caused by cavitation. What are two ways to repair this?
- an epoxy followed by smoothing it out once hard (minor damage)
- machined and re-sleeved (major damage)
True or false:
With multi-piece engine blocks, the engine must be completely disassembled to remove the crankshaft.
true
On what type of engines is it critical that the counter bore depth be within tolerance?
engines that have a common head
What could happen if an engine bore is out-of-round or not concentric?
cylinder scuffing and abnormal wear;
the liner will take the shape of the bore
What is the deck height of an engine block?
the distance from the main bearing bore centre to the top surface where the head is bolted on
Which aspect of an engine would change if the deck height of the block was reduced?
the compression ratio;
this is because the clearance volume would be decreased
What two measurements are changed when an engine block deck is resurfaced?
- the piston to head clearance
- the block deck height (centre of the crankshaft to the top of the block deck)
What measurement needs to be verified if an engine block deck height is machined?
the block deck height to the centre of the crank
What condition would cause the crankshaft to bend continually as it rotates?
misalignment of the main bearing bores
How can the alignment of the main bearing bores be checked on high-speed engines?
with a straight edge and feeler gauges
*high-speed = small
What are two ways that the main bearing bore alignment can be checked on larger engines?
- if the crankshaft is removed ⟶ piano wire, laser or optical methods
- if the crankshaft is in place ⟶ deflection gauge placed between the webs
How would the main bearing bores of a large engine be checked if the crankshaft is in place?
with a deflection gauge between the webs of the crankshaft
How would the alignment of the main bearing bores of a large engine be checked if the crankshaft has been removed?
piano wire, laser or optical methods
True or false:
If the deflection of a large engine crankshaft is out of spec, it may be possible to shim the frame to correct the problem.
true
What is the maximum allowable deviation of main bearing bores in an engine?
no more than 1/2 the maximum allowable main bearing clearance
What is the recommended fix for main bearing bores that are misaligned in high-speed engines?
line boring
What are two methods of measuring the size and concentricity of the main bearing bores be checked in an engine?
- inside mics and transfer gauges
- dial bore gauge
How must an engine be set up in order to measure the size and concentricity of the main bearing bores?
the crankshaft removed and the main bearing caps in place and torqued to specifications
How many measurements should be taken to measure the size and concentricity of the main bearing bores of engines?
two sets (front and back) of three measurements, 120º from each other
What are two repairs that can be done to an engine block that can change the compression ratio if not accounted for?
- resurfacing the engine block deck
- line boring the main bearings of the crankshaft
*these are the two locations that make up the block deck height to the centre of crankshaft measurement
True or false:
Repositioning the bearing bores has the same effect on compression ratio and piston-to-cylinder-head clearance as resurfacing the block.
true
In this engine repair procedure, material is removed from the parting surface of the main bearings caps, which are then reassembled before being machined back to specifications.
line boring
*removing material from the parting surface of the main bearing caps results in an oval shape, which needs to be bored out to round once in place
One type of repair that can be done to damaged crankshaft main bearing journals is to machine down the crankshaft and use undersized bearings. What effect does this have on the crankshaft?
it can unbalance the crankshaft
*undersized bearings ⟶ bearings with a smaller ID but the same OD
True or false:
The highest amount of main bearing bore alignment deviation allowed, is no more than half of the maximum main bearing clearance at new condition.
true
What happens to the engine if the cylinder is not straight and smooth?
blow-by will be excessive
this will result in less energy harnessed by the engine, excessive oil consumption and crankcase pressures.
How can engine cylinders that are cast as part of the block repaired?
bored to a larger size
When referring to engines, what are liners or sleeves?
the cylinders
What are two ways removable engine liners held in the block?
- by the cylinder head
- studs passing through the liner and cylinder head
What are the three types of removable cylinder liners found on large engines?
- dry liners
- wet liners
- air-cooled liners
- What is the highest wear area on a cylinder?
- Why is this?
- top of liner, towards the major thrust side of the liner
- the high temperatures, pressures, and minimum lubrication
What are three methods to treat the inside of a cylinder in order to reduce wear?
- induction hardening
- hard chrome
- nitriding
Why should chrome piston rings never be used inside a chrome lined engine liner?
two very hard surfaces will prevent break in of the seals along with the potential for galling
This type of engine cylinder liner fits inside the bores and does not contact the coolant.
dry liner
This type of engine liner has a slide (transition) fit, and requires good contact with the bore in the block for heat transfer.
dry liner
This type of engine liner is reliant on the bore in the block to help it form the correct shape and diameter.
dry liners
Which type of cylinder construction would be most effective at transferring heat away from the cylinder bore?
wet liners
Which type of liner has thinner walls: a dry liner or a wet liner?
a dry liner
What is the purpose of the liner flange on both wet and dry liners?
to prevent movement once the cylinder is bolted down
This type of engine liner is in direct contact with the coolant.
wet liners
Why are wet liners thicker than dry liners?
they must be strong enough to withstand the combustion pressures
What is the most common type of liner in industrial engines?
wet liners
Which type on engine liner would have O-rings to prevent coolant from entering into the crankcase?
the wet liners
This type of liner will have cooling fins that surround the outer diameter of the cylinder.
air-cooled liner
What type of two-stroke engine cylinder liner has the liquid coolant passages built into the liner itself?
integral
Engine liners that feature porting on them near the middle of the cylinder are used on ________-stroke engines.
two-stroke
What is scavenging in an engine cylinder?
where some intake air is used to help flush out the exhaust
*happens on the exhaust stroke
This type of two-stroke engine liner is used on very large engines and features a flange at the bottom that is bolted to the block along with a dry liner that is shrunk-fit into the cylinder block.
flange mounted liner
Normally, the exhaust port on a two-stroke cylinder will be large and closer to TDC. What does it mean if all the ports on a two-stroke liner are the same height?
that there are only intake ports on the cylinder wall, and this uses an exhaust valve
True or false:
When rebuilding an engine, the engine liners should be removed before measuring them for wear.
false;
measure them in the block ⟶ liners can become distorted out of the block, which could result in erroneous measurements
What causes the thrust side of wear in an engine liner?
the angle of the con-rod
- On what stroke is the major thrust side wear created?
- On what stroke is the minor thrust side wear created?
- the power stroke
- the compression stroke
When measuring an engine liner for wear, where should these measurements be taken?
in the area of piston ring travel
True or false:
For an engine liner to function properly, it must be straight, round and within the proper dimensions.
true
- In what shape do engine cylinders normally wear?
- Why is this?
- with a taper towards TDC
- this side has high pressures, temperatures, and less lubrication
When checking an engine liner, what does a ridge that you can feel with your finger nail indicate?
the cylinder is excessively worn, and cannot be reused
How should an engine cylinder be measured to determine out-of-round and taper?
two sets of three measurements (top, middle, bottom);
one set in line with the crank, with the other 90º to the crank
What is one way to salvage engine liners that have cavitation pitting?
reinstalling the liners 90º (to their original position)
True or false:
Engine liners that are to be reused should be marked so that they can be reinstalled in the same position during assembly.
true;
they will have worn to the bore of the block, which could result in excessive wear if installed into a different location
True or false:
Engine liners should be stored horizontally (on their side) while waiting for installation.
false;
they should be stored vertically ⟶ this prevents them from becoming distorter or egg shaped over time
On engine liners, _______________ is severe scratches and abrasion along the cylinder walls.
scoring
This engine liner issue is caused by the cylinder and rings becoming too hot, which results in compression loss and oil consumption.
scoring
This engine liner issue is the loss of metal on the outside of the liner, which affects heat transfer.
corrosion
*only found on wet liners
This engine liner issue is the wearing of the outside of the liner by abrasive particles in the coolant, which reduces the rate of heat transfer.
erosion
What effect does erosion have on heat transfer in an engine liner?
it reduces the heat transfer
What three things cause flange cracks in engine liners?
- distorted block
- over-torquing the head bolts
- wrong liner protrusion
This engine liner issues can result in leaking coolant, leaking compression or combustion gases, or parts of the liner breaking off and migrating towards the crankshaft.
flange cracks
This engine liner issue is usually caused by overheating, hot spots, or piston seizure.
liner cracking
This engine cylinder issue causes discolouration of the liner.
overheating
What is a common cause for engine liner discolouration?
overheating caused by poorly fitted liners
- This engine liner issue presents as small pinholes that appear on the coolant side of the liner.
- What causes this issue?
- cavitation
- liner vibration ⟶ as the liner vibrates quickly, the liner moves away from the coolant faster than the coolant can move, resulting in a low pressure area right next to the liner wall, which causes cavitation
What are four solutions to cavitation of a wet engine liner?
- pressurizing the coolant system
- plating the outside of the liner
- adding additives to the coolant (nitrite or chromates)
- increasing the liner wall thickness
This engine liner issue is caused by dust or fine particles coming through the air filter or leaks in the intake system.
abrasion;
excessive or premature liner wear
What two issues do cylinder ridges caused in engine liners?
- make it difficult to remove the piston
- new piston rings or piston ring lands can hit the ridge and break when the engine is started
How can a cylinder ridge be removed in engine liners under 6 inches (150mm) in diameter?
with a ridge reamer
How can a cylinder ridge be remove on engine liners over 6 inches (150mm) in diameter?
a rotary burr and/or hone
When reconditioning a cylinder bore, you can use a de-glazing hone to:
restore cylinder wall crosshatch pattern
True or false:
Flexible hones and de-glazers can be used to straighten out engine cylinders.
false;
they only remove polish and glazed surfaces and produces a cross-hatch pattern in the cylinder
In an engine liner, what angle should the crosshatch pattern be?
40º to 60º
What two tools are used to de-glaze an engine liner?
- flexible hone
- ball de-glazer
True or false:
A drill speed of 300 to 400 rpm, while making one complete vertical stroke per seconds, produces the correct crosshatch pattern in an engine cylinder.
true
What type of grit stone would be selected to create a surface finish of approximately 20 micro-inches when de-glazing an engine cylinder?
180 to 200 grit stone
What effect does the correct crosshatch pattern on a cylinder wall have on its lubrication?
the crosshatch holds oil;
without it, the cylinder wall will not seal properly
How must an engine cylinder be cleaned after being de-glazed?
with a bristle brush and hot soapy water
Can solvent be used to clean an engine cylinder after being de-glazed?
no;
the solvent will not thoroughly flush the material and abrasives from the microscopic grooves
If an engine cylinder can be bored to the next oversize, it is recommended to bore about 1.5 thousandth of an inch short and then use a rigid hone to finish it to size. Why is this?
the finish left by a boring tool would be too rough
If the taper and wear of an engine cylinder are not more than _______”, the cylinder can be made straight with a rigid hone.
0.002”
What tool can be used to make an engine liner straight and around?
a rigid hone
*max taper or misalignment is 0.002”
Why is it critical that the bore in an engine block be circular when using dry liners?
dry liners follow the shape of the bore in the block
What repair can be done to repair engine block bores that are out-of-round?
the can be machined to accept liners with an oversized OD
When installing a wet liner into an engine block, what effect can twisted O-rings have on the liner?
they distort the liner, leading to out-of-round liners and possible seal leaking
What should be placed under the top liner flange of an engine cylinder to help seal it?
a bead of high temperature, room temperature vulcanizing sealant
True or false:
You can repair cylinder liners on large engines by hard chroming and grinding to size.
true
Why is alloy cast iron used for engine block material?
the alloy cast iron has excellent heat transfer properties
True or false:
An improper outside diameter fit of a dry liner can cause coolant to leak into the crankcase.
true
This method of repairing cast iron engine blocks is desirable because it doesn’t produce a heat affected zone.
cold stitching
What is the recommended accuracy of a web deflection gauge?
0.0001”
Another term for the cylinder head mounting surface would be;
Deck
Which method of treating the inside of cylinder liners to improve wear resistance involves heating the liner in a nitrogen rich atmosphere?
Nitriding
Which engine block measurement can be affected by adding a bead of RTV sealant under a liners flange?
liner protrusion
True or false: Worn or scored cylinder liners affect engine performance and oil consumption, and lead to increase in crankcase pressure.
True
True or false: Oil control rings depend only on their expanders to maintain contact with the cylinder walls.
True
True or false: After torquing the connecting rod bolts the rod should be checked for adequate side clearances.
True
True or false: The best method of checking a cylinder head for coolant leaks would be to use the hot water and pressure method.
True
True or false: A valve seat ground too wide will cool the valve better but will trap carbon.
True
True or false: The greatest degree of wear on the cylinder liner is on the top of the ring travel 90° to the crankshaft.
True
What type of alloys should caustic cleaning solutions not be used with?
aluminum;
caustic solutions attack and erode aluminum
