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