Cylinder Block Inspection and Service Chapter 10 Cylinder Block Inspection and Service

Objectives Analyze wear and damage to cylinder block Select and perform most appropriate repairs to block

Objectives R&R cam bearings, galley plugs, and core plugs Explain theories of cylinder wall surface finishes

Cleaning the Block Disassemble Remove all core plugs and oil gallery plugs Remove cam bearings Hot tank block and flush thoroughly to remove caustic solution and sediment

Cleaning the Block Lubricate all machined surfaces Check block for cracks in cylinder bores and lifter valley

Oil and Water Plugs Must be cleaned after hot tanking to prevent loosened particles from entering engine after reassembly Use a stiff bristle brush with hot soapy water

Oil and Water Plugs Three types of gallery plugs Female plug Male plug Allen-type plug

Oil Jet Cooling Original intent of the jets on the inside of piston was to provide lubrication to wrist pins Pistons are prone to increased heat, thus cooling this area is important Be careful when removing jets to clean the oil galleries

Aligning Dowels on the Back of the Block Dowels align the transmission or transaxle housing to the engine Aligning dowels should be in good condition to avoid misalignment Sweet transmission pump area with dial indicator attached to the crankshaft if misalignment is suspected

Main Bearing Caps and Registers Fit in to machined slots in block Bores are bored at factory with caps in place Caps are not interchangeable

Main Bearing Caps and Registers Some engines use four or more bolts to support main cap Some engines use a bedplate for extra strength

Main Bearing Caps and Registers

Main Bearing Bore Alignment Repeated heating and cooling of an engine block Can cause misalignment of main bearing caps Check main bearing saddle bore alignment with feeler gauge and straight bar Blocks can be remachined to correct misalignment

Main Bearing Bore Alignment

Checking Main Bearing Bore Alignment Coat main journals of crankshaft with Prussian Blue Install crank and bearings I block After torquing main caps, rotate crankshaft twice

Checking Main Bearing Bore Alignment Turn engine upside down and rotate engine twice Carefully unbolt main caps and remove crank At least 75% of bearing area should be “blued” for acceptable alignment

Decking the Block Clean deck surface with a file or whetstone Remove any nicks or burs that may give false readings Use a straight edge and a feeler gauge to check block deck for flatness

Decking the Block If block shows warpage, block should be decked Machine shop will use a grinder or milling machine to deck block

Inspecting Cylinder Bores Inspect cylinders for taper and out-of-round wear Maximum wear is at 90º to wrist pin Due to lack of lubrication at top of cylinder

Inspecting Cylinder Bores Top of cylinder is subject to high pressure of the piston rings against cylinder wall When air-fuel mixture is ignited

Measuring the Bore Square ring just below ring ridge Measure ring gap with feeler gauge Compare this measurement to butt gap measurement taken at bottom of cylinder

Measuring the Bore To determine taper, divide difference between the two gaps by three

Deglazing Cylinders with Engine in Car Rotate crank to BDC Put a length of hose on bottom of glaze breaker This prevents it from damaging crankshaft

Deglazing Cylinders with Engine in Car Newspaper at bottom of bore will protect crank from oily grit It is not necessary to stroke all the way to bottom of cylinder

Clean the Block of Grit Hand brush or use air drill Ordinary cleaning solvent will not lift grit from pores of metal Check cylinder walls and crankcase for cleanliness

Clean the Block of Grit Following cleaning Grit can often be found in crankcase area just under cylinder bores

Reboring Cylinders Cylinders with excessive or unusual wear or rust should be rebored Following boring Cylinders are honed to fit new oversized pistons Popular oversize .020", .030", and .040"

Reboring Cylinders Small change in compression ratio will occur when boring

Ultrasonic Thickness Testing Used to check thickness of cylinder walls Determines if enough material exists in block to safely bore cylinder Considered a non-destructive tester

Ultrasonic Thickness Testing Can produce sound waves from 500 KHz and 100 MHz Higher frequencies for thinner materials Lower frequencies for thicker metals

Honing Cylinders Two stones and two aluminum guides on a rigid hone Ensure guides are not too tight against cylinder walls As honing of each cylinder is completed Allow stones to run with very little pressure for several strokes

Honing Cylinders Stroke hone at speed necessary to generate a crosshatch of between 20º and 30º off horizontal surface of block

Cylinder Surface Finish One micro-inch is one millionth of an inch Higher micro-inch number Means rougher finish Average finish recommended 25 to 30 micro-inches

Cylinder Sleeves Cylinder sleeve can be used to fix a cracked, rusted, defective cylinder Most sleeves come with a 1/8” or 3/32” wall thickness

Cylinder Sleeves To install sleeve Bore block Cool sleeve and heat block Press in sleeve

Final Block Preparation Clean block with soap and hot water Oil machined surfaces Clean all bolt holes If block has been decked Bolt holes can be chamfered at top to remove burrs Clean out galleries with rifle brush

Oil Gallery Plug Installation Coat threaded oil gallery plugs with sealer or Teflon tape and tighten into block Install press fit core plugs with red loctite Cross stake outside of core holes with cold chisel

Oil Gallery Plug Installation

Coolant Core Plug Installation Clean core holes in block with emery cloth Put sealer on outside of core plug and drive into block Lip is just past chamfer when core plug is properly installed on block Core plugs of same diameter can have different depths

Coolant Core Plug Installation