Engine Bottom End – Know The Parts Inside Your Engine

Engine Bottom End - Know The Parts Inside Your Engine
Engine Bottom End - Know The Parts Inside Your Engine

The engine bottom end, is by far the most important part of the engine.

But, the engine bottom end, is not just one thing. Because, it is made up of, it’s own list of parts.

And, all of these engine bottom end parts, must work together properly to form a healthy engine.

So, a lot of research has been made, to improve performance of automobile engines, by improving engine bottom end parts.

Furthermore, not all engine are the same or even include, the same engine bottom end parts. Consequently, most of that depends on the year, make, model and engine size with different options.

Engine Bottom End Parts - Know The Parts Inside Your Engine
Engine Bottom End Parts – Know The Parts Inside Your Engine

So, there is a list of the most common engine bottom end parts. Also, engine parts are usually grouped together in different categories. And, each of these categories, has their own list of parts.

Some Of The Common Names For These Category Groups Are:

  • Engine Bottom End
  • Engine Top End
  • Front End
  • Oil Pan
  • Valve Cover
  • Front Or Timing Cover
  • Intake And Exhaust Manifolds
  • Also, A Hole List Of External Parts

Engine Bottom End Parts, Included In the Category, Bottom End

Engine Bottom End Parts
Engine Bottom End Parts

Short Block

  • So, the short block includes, the cylinder block with all of its internal parts installed. The pistons, rods, crankshaft, and bearings, would be in the block.

Bare Block

  • A cylinder block with all parts removed. So, there would not be pistons, rods, a crankshaft, nor other parts in the block.

Block Deck Surface

  • A flat machined surface, for the cylinder head.

Cylinders (part of engine bottom end )

  • Large holes machined in the cylinder block. So, one hole per cylinder. An integral cylinder, is part of the engine block.

Cylinder Block Sleeves Or Liners

  • Another way to make a cylinder in the engine. Sometimes sleeves are used for block repairs. So, there are two basic types of cylinder sleeves, dry sleeves and wet sleeves.

Machined Holes And Bores

  • There are several machined holes and bores, in the engine block. Some include, lifter bores, cam bores, main bores, oil galleries and water jackets.

Main Bearing Caps

  • So, the bottom of the engine block, have main bearing caps bolted to it. Consequently, forming one-half of the main bore. Large main cap bolts, screw into holes in the block, to secure the caps to the block.

Main Bearings

  • Main bearings snap-fit into the cylinder block and main caps, to provide an operating surface for the crankshaft main journals.

Crankshaft (part of engine bottom end )

  • So, the crankshaft convert the reciprocating motion, into a rotating motion. The crankshaft fits, into the main bore of the block. The crankshaft has oil passages, counterweights, and a crankshaft flange. Sometimes with a pilot bearing in the center, to support the manual transmission input shaft.

Crankshaft Main Journals

  • Precision machined and polished surfaces, that ride on the main bearings.

Connecting Rod Journals

  • Precision machined and polished surfaces, that ride on the rod bearings.


  • The flywheel is one of the most important, engine parts. It is a large and heavy metal wheel. So, the flywheel is attached to the back of the crankshaft, to smooth out the firing impulses. It provides inertia, to keep the crankshaft turning smoothly, during the periods, when no power is being applied. It also forms a base, for the starter ring gear and in manual transmission, for the clutch.

Connecting Rod

  • A connecting rod, is the part of a engine which, connects the piston to the crankshaft. Together with the crank, the connecting rod converts, the reciprocating motion of the piston, into the rotation of the crankshaft.

Connecting Rod Cap

  • The connecting rod cap, bolts to the bottom of the connecting rod body.

Rod Bearings

  • The connecting rod bearings, snap-fit into the connecting rod, to provide an operating surface, for the crankshaft rod journals.

Piston (part of engine bottom end )

  • The piston is a solid cylinder of metal, which moves up and down, in the cylinder of the engine block. Its purpose is, to transfer force from expanding gas in the cylinder to the crankshaft.

Wrist Pin ( piston pin )

  • The piston pin, allows the piston to swivel on the connecting rod. The piston pin, fits through the hole in the piston and the connecting rod small end.

Piston Rings

  • A piston ring is a split ring. It sits on the outer diameter of a piston. Piston rings have multiple functions. Piston rings, seal the combustion chamber, so that there is minimal loss of gases to the crankcase. Also, dissipate heat from the piston to the cylinder wall. Maintain the proper quantity of oil, between the piston and the cylinder wall. Finally, regulate engine oil consumption, by scraping oil from the cylinder walls, back to the oil pan.

Balance Shafts

  • So, to reduce vibration, balance shafts are used. These counterweighted shafts, are generally mounted in the left and right side of the engine block.

Oil Pump

  • So, the oil pump circulates engine oil, under pressure to the rotating bearings, the pistons and the camshaft. As a result, the oil pump lubricates, all the moving parts inside the engine, while cooling the engine.

Oil Pan And Sump

  • The oil pan, normally made of thin sheet of metal or aluminum, bolts to the bottom of the engine block. It holds an extra supply of oil, for the lubrication system. The sump is the lowest area in the oil pan, where oil collects.
Engine Break Down
Engine Break Down

So, as you can see, there is a whole list of parts, that make up the engine bottom end. Stay tuned for more information, as we expand to some of the other categories mentioned above.


So, automotive engines may seem complicated, but their task is simple, to propel your vehicle forward. And, there are many parts working together to create this motion. As a result, it’s imperative your vehicle receives proper maintenance, to ensure their longevity. Finally, regularly scheduled oil changes, fluid flushes, and changing belts and hoses at the recommended time, is a great way to help prevent the unfortunate circumstance of a failed engine.

Thank You !