Medium/Heavy Duty Truck Engines, Fuel & Computerized Management Systems, 3E Chapter 9 Engine Housing Components

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1 Medium/Heavy Duty Truck Engines, Fuel & Computerized Management Systems, 3E Chapter 9 Engine Housing Components

2 Introduction Internal engine components are contained in the engine housing components The cylinder block is the engine s frame All other engine parts are attached to this frame

3 The Block As A Foundation Intake Manifold Cylinder Head Assembly Exhaust Manifold Engine Cylinder Block Oil Pans Cylinder Liners

pressures Occurs when twist forces from the crankshaft anchor through the cylinder block Thermal

4 Engine Cylinder Block Forces: Torque twisting Cylinder pressure Thermal shock The block can be subject to forces either as a result of crankshaft input or output Driveline forces High cylinder pressures Occurs when twist forces from the crankshaft anchor through the cylinder block Thermal shock can occur when a hot cylinder block is subject to sudden cooling such as cold water in a wash bay

5 Illustrated Block Terminology

6 Cylinder Block Design Support Crankshaft & flywheel (power take off assembly) Cylinders Camshaft(s) Cylinder bores Replaceable at overhaul. Replaceable cylinder liners Integral bores (referred to as Parent bore blocks) Configuration of choice inline 6 cylinder

7 Cylinder Block Design Additional casting considerations Water jacket Coolant passages Lubricant passages Engine blocks have many openings constructed to assist with the casting & machining processes. These are plugged in service

8 Cylinder Block Materials Traditional Grey cast iron Considerations Material Weight Rigidity Fatigue factor Power to weight CGI Current 700% lighter 40% better 200% improved Twice by comparison CGI cylinder blocks have been a key to reducing engine weight over the past five years!

9 Engine Block Design Recap Incorporate bores for piston assemblies Incorporate bearing bores for crankshaft mounting Some may contain longitudinal bores for camshafts Incorporate coolant passages & water jacketing Incorporate lubricant passages/drillings Incorporate mounting locations for other components Be of the lightest weight possible Be strong enough to withstand cylinder pressures

10 Cylinder Block Categories By Bore: Integral cylinder bore or parent bore Wet sleeve/liner Dry sleeve/liner Combination wet/dry liners Other factors such as two-stroke cycle & air cooled aspects are also reflected in block design

11 Integral Cylinder Bore Less often seen in truck diesel engines Used on most small bore & automobile engines Known as throw away blocks when used on medium bore applications Advantages: Lower initial cost No liner seals to fail Initial cost savings may be compromised at rebuild if the block requires either replacement of a boring sleeving machining operation No liner protrusion dimensions to adhere to on reassembly

12 Induction Hardened Parent Bore Introduced by Freightliner/Mercedes-Benz late 1990s Family includes 4 & 6 engines Features: Unique helical striped induction hardening In the upper ring belt sweep area. This gives the bore a considerably extended service life compared to other parent bore engines If the bore becomes worn to oversize they can be bored and sleeved This engine has become very successful in both on and off highway applications!

13 Wet Liner/Sleeve Designed to allow the water jacket direct contact with the liner Possess superior metallurgical characteristics Liner must have a wall thickness sufficient to sustain peak combustion pressures Wet liners transfer heat efficiently into the coolant Wet liners are easily replaced at overhaul Disadvantage: Liner seals must be maintained for life of the liner Seal failure results in coolant contaminated engine lubricant

14 Wet Liner Cavitation Problem caused by coolant vapor bubble implosion Can shorten liner life Seldom a problem if coolant chemistry is monitored How does cavitation occur? Wet liners are subject to cylinder pressures Liners expand outwards into wall of surrounding coolant Liners contract creating a low pressure void bubble When the bubble collapse coolant collides with sleeve Condition repeats at high frequency

15 Liner Seals O rings are used to seal wet liners Made from a variety of compounds: Rubber type = 100% rubber or derived from petrochemicals Adhere to OEM installation recommendations Some may recommend: Dry Coated in coolant, soap or engine oil or various other substances Some O rings are designed to react to the coating substance and swell to create a perfect seal

16 Dry Sleeves Thinner walled than the wet sleeve Held in place by cylinder head Heat transfer not as efficient as wet sleeve Easily replaced Does not present coolant leakage problems Older Application Cast iron construction Installed with fractional interference fit Current Application Alloyed metal construction Designed to be installed loose

17 Dry Sleeves Both liner styles are designed to maximize heat transfer. The older application used a tighter interference fit to increase metal to metal contact & heat conductance The current application, with its engineered greater coefficient of heat expansion is designed to be installed loose and expand into the block bore, increasing the contact area & the ability to transfer heat If this current liner style is installed with an interference fit, they will buckle in use, greatly reducing service life

18 Combination Wet/Dry Sleeves Designed with the hottest part of the sleeve in direct contact with coolant The lower part fits directly into the cylinder block The upper section has more mass to contain the cylinder combustion pressures O rings are traditionally used for sealing

$Cylinder Sleeve Removal Sleeves should be removed with a puller & adapter plate or shoe Avoid fracturing seized$

19 Cylinder Sleeve Removal Sleeves should be removed with a puller & adapter plate or shoe Avoid fracturing seized liners out of their bores as this will almost always result in bore damage In extreme situations, liners may be machined out

20 Piston Removal To assist with piston removal from the cylinder liners, remove the carbon that forms around the wear ridge. The carbon may be removed with a flexible knife blade followed by gentle use of emery cloth

21 Block Serviceability Checks Strip block completely including expansion cups and gallery plugs Soak in a hot or cold tank with the correct cleaning solution Check for scaling in the water jacket not removed by soaking Check for excessive erosion around the deck coolant ports & fire ring seats Electromagnetic flux test the block for cracks at each out of chassis overhaul

bar Check the engine service history to ensure the engine has not been

22 Block Final Inspection & Assembly Check for deck warpage using a straight edge & thickness gauge Check the main bearing bore & alignment with a master bar Check the engine service history to ensure the engine has not been previously line bored Check the cylinder counter bore for correct depth & circumference

23 Block Final Inspection & Assembly Check the cam bore dimensions & install new cam bushings Always use correct cam bushing installation equipment Ensure that the cam oil holes are correctly aligned before driving each bushing home Install all gallery & expansion plugs

24 Liner & Sleeve Reconditioning Not a current common practice Limiting factors: Technician time limitations Projected service life compared to new Some OEMs offer oversize liners Used if block is damaged & over-bored to save Two basic reconditioning methods: Glaze busting Honing

25 Liner & Sleeve Reconditioning Glaze busting: Liner is checked & is within serviceablity specs Glaze busting removes the least amount of material Best tool = flex hone Goal of glaze busing: Remove cylinder carbon ridge Re-establish crosshatch Rotate the hone at 120 to 180 RPM, using rhythmic reciprocating thrusts

Liner & Sleeve Reconditioning Honing Performed with a rigid hone Powered at low speeds Typical hone has 3 legs A radial load is applied to legs Abrasive grit rating determines

26 Liner & Sleeve Reconditioning Honing Performed with a rigid hone Powered at low speeds Typical hone has 3 legs A radial load is applied to legs Abrasive grit rating determines aggressiveness grit rating typical Some boring tools can be programmed to produce specific cross hatch This is a typical cross hatch pattern produced by honing with grit stones

Creating Crosshatch 60 o -- to 70 o horizontal crossover angle Clearly visible to the eye 15 20 micro-inch crosshatch Crosshatch designed to hold oil so that the rings may effectively seal Some OEMs

27 Creating Crosshatch 60 o -- to 70 o horizontal crossover angle Clearly visible to the eye micro-inch crosshatch Crosshatch designed to hold oil so that the rings may effectively seal Some OEMs express this as 120 o 130 o vertical crosshatch If using a handheld tool, remember a few short strokes with a moderate radial load tends to produce a better pattern than many strokes with a light radial load!

28 Fitting Liners Selective fitting of liners is good practice Measure the block bore across: North south faces East west faces Grade in order of size Measure OD of new liners Grade liners in order of size Ensure all measurements fall within OEM specs! Fit the largest liner to the largest bore & continue in sequence for the rest

29 Flywheel Housing Bolts to rear of engine block Forms stationary coupling -- engine to transmission Categorized by SAE code Permits similarly coded transmission to couple Allows transmission OEMs to fit their product to a variety of different OEM engines Encloses flywheel and clutch pack May incorporate rear engine mounts Some rear engine mounts may be attached to the transmission bell housing Starter motor usually flange mounted to housing

30 Flywheel Housing Precisely located to block by dowels Clamping force provided by fasteners Flywheel housing should be checked for: Flange ID radial concentricity Outer flange face runout

31 Cylinder Heads Seal engine cylinders Manage engine breathing Usually cast iron May support rocker assemblies & camshafts Configurations: Multi cylinder, single slab casting Multi cylinder, multiple cast units Single cylinder

32 Cylinder Heads Disassembly Refer Check Dress Recondition to gasket cylinder OEM valves surfaces Literature head height with Inspection Remove dimension emery Check valve cloth valves springs Reconditioning Clean Pressure Check cylinder for valve test warpage rotators head 3. Electromagnetic If replacing injector flux tubes, test for Check the service literature. Each OEM has its Once cracks use own If the the preference appropriate springs engine have is & equipped methods been tools compressed (with Preferably with a C-type variable compressor) in a timing hot soak or gently tank tap each 4. valve Check engine with a valve brake nylon actuators, hammer guides to loosen the 5. keepers Recondition there & retainers is usually a valve very seats specific procedure to After valve & seat reconditioning, observe always. check valve head height (valve protrusion) with a dial indicator!

33 Cylinder Head Installation Head gaskets are designed to seal engine components in a region where both the temperature & pressure are at their highest. They must do this & at the same time accommodate a large amount of component creep Creep is the relative movement of clamped engine components due to different coefficients of heat expansion The head gasket is key to maintaining an effective seal under all operating conditions

34 Cylinder Head Installation Gasketed fit to engine block Most current head gaskets are integral The head gasket must be properly torqued to ensure the yield point is attained for proper sealing Always observe OEM torque increments & sequencing Most gaskets require no sealant

35 Cylinder Head Torque Process Fasteners should be lightly lubed before installation Multi-cylinder heads must be aligned on the block Failure to observe torquing increments & sequences may result in: Cracked cylinder heads Failed head gaskets Fire rings not sealing correctly Use a click type torque wrench Many manufacturers use torque-to-yield fasteners

36 Rocker Housing Covers Seals upper portion of engine above cylinder head Most frequently removed engine component Removed for Tune-up Access to valve mechanism & injectors Many OEMs have adopted a multi use gasket Rubber compound fitted to a capture groove More costly than fiber predecessors Always follow OEM installation recommendations Avoid using aggressive adhesives

37 Manifolds Intake Delivers intake air to the cylinders Delivers recirculated exhaust gas to the cylinders Bolted to the cylinder heads enclosing intake tracts May be either wet or dry Usually constructed of aluminum or cast iron Mounting gaskets = fiber (accommodates minor creep ) Accommodates up to 100 psi of boost pressures

38 Manifolds Exhaust Collects cylinder end gases Delivers these gases to: The turbocharger Directly to the exhaust piping in naturally aspirated engines Usually manufactured from cast iron May be have single or multiple sections Manifold should be aligned before torquing Gaskets are usually of the embossed steel type Manifold fasteners need to accommodate high temperatures & high thermal expansion/contraction rates

39 Oil Pans or Sumps A reservoir Located on the base of the engine block Completes the enclosure of the crankcase Could be manufactured of: Cast aluminum Stamped mild steel Laminated steels Various plastics or synthetic fibers Collects lubrication oil delivered by gravity from the engine Oil pump pickup collects oil from the sump & recycles it through lubrication circuit

40 Oil Pans or Sumps Can amplify engine resonance Usually designed to minimize noise: Laminated steels dampen noise & add toughness Plays a role in dissipating lube oil heat Effectiveness related to material of manufacture Can produce problems in cold conditions Some off highway units use a deep sump & a scavenging pump

41 Oil Pans or Sumps Located in air flow under the frame rails Vulnerable to damage Objects from the road Rocks on rough terrain Most oil pans can be removed from engine while still in the chassis Always drain the sump before removal Never drive sharp objects between the pan and block to assist with removal

42 Oil Pans or Sumps Inspection & reinstallation Scrap gasket surfaces Clean with a pressure washer Check for cracks Check drain plug threads Always observe torque specifications & sequence

43 Location Review Rocker housing covers Cylinder block Cylinder heads Intake manifold Exhaust manifold Liner O rings Cylinder liners Flywheel housing Oil Sump

44 Summary The engine cylinder block is the main frame of the engine Cylinder blocks are manufactured of grey cast iron or compacted graphite iron Most truck diesel engines use either Sleeves make engine overhaul easier & faster & extend engine life

45 Summary Some small bore engines use parent bore blocks that are induction hardened Dry liners are fitted to the block fractionally loose or with a fractional interference fit Dry liners do not transfer cylinder heat to the coolant in the water jacket as efficiently as wet liners Selective fitting of dry liners to cylinder block bores ensures the best liner to bore fit Wet liners must seal the water jacket using O rings

46 Summary Wet liners transfer heat more efficiently because they are surrounded by coolant Wet liners need to support combustions pressures Liners are clamped into position by the cylinder heads Protrusion of the liner flange is a critical specification Liner protrusion is set by shimming the counterbore Engine blocks must be thoroughly checked at each overhaul

47 Summary The cylinder head houses: The valve train assemblies The injectors The engine breathing passages The cylinder block should be tested hydrostatically first by heating thoroughly with hot water Common location for cracks include the injector bore tubes & the valve seats Cylinder heads must be torqued in sequence to ensure even clamping pressure

48 Summary Torquing the cylinder heads in increments achieves the head gasket yield point by evenly reaching the required clamping force Cylinder head bolts should be lightly oiled with engine lubricant before installation The intake manifold is responsible for directing the intake air & recirculated exhaust gas into the cylinder head intake tracts Gaskets used to seal the engine housing must be able to accommodate dynamic creep without failing. For this reason gaskets are single use

49 Summary Most truck diesel engines refer to their exhaust manifolds as tuned because they feed the turbocharger turbine housing The way the exhaust gas is moved through the manifold is critical for scavenging end gases

CRANKSHAFT & MAIN BEARINGS

CRANKSHAFT & MAIN BEARINGS * PLEASE READ THIS FIRST * REMOVAL Ensure all main bearing caps are marked for location on cylinder block. Some main bearing caps have an arrow stamped on them. The arrow must