- - AGRICULTURE CORE CURRICULUM - - (CLF2000) Advanced Core Cluster: AGRICULTURAL MECHANICS (CLF2850) Unit Title: TYPES OF ENGINES __________________________________________________________________________ (CLF2855) Topic: ENGINE DISASSEMBLY Time Year(s) AND REASSEMBLY 5 Hours 1 / 2 / 3 / 4 __________________________________________________________________________ Topic Objectives: Upon completion of this lesson, the students will be able to: Learning Outcome #: (R-10) - Disassemble and reassemble an engine. Special Materials and Equipment: Various internal combustion engines, tools and facilities appropriate for engine removal, parts cleaning, and assembly References: Jacobs, C. O., & Harrell, W. R. (1983). AGRICULTURAL POWER AND MACHINERY. New York: McGraw-Hill. Resources: Deere & Company. (1984). PREVENTIVE MAINTENANCE (Fundamentals of Machine Operation (FMO) Series). Available from: John Deere Technical Services, Dept. F, John Deere Road, Moline, IL 61265 Evaluation: Unit exam and completion of an engine assembly and disassembly project. TOPIC PRESENTATION: ENGINE DISASSEMBLY AND REASSEMBLY A. Disassembling the Gasoline Engine 1. Engine Removal a. Top of engine preparation for removal 1) Provide yourself with an open space, and have on hand containers and markers for keeping track of parts. 2) Remove the engine hood. 3) Remove the battery and battery cables. 4) Drain the cooling system at the radiator and at the cylinder block. 5) Remove the air cleaner and intake duct assembly. 6) Disconnect the upper and lower radiator hoses. 7) Remove the bolts attaching the fan shroud to the radiator, if so equipped. 8) If equipped with power steering, remove the power steering pump. 9) Remove any other lines, wires, or hoses attached between the engine and chassis. 10) Remove the alternator and its mounting bracket. a) Move them to the side, but don't disconnect them. 11) Disconnect the fuel inlet line at the fuel pump; plug or cap the line to prevent fuel loss. 12) Disconnect the accelerator cable or linkage at the carburetor and intake manifold. 13) Disconnect the engine wiring harness from the water temperature sending unit, the oil pressure sending unit, etc. 14) Remove the carburetor from the engine. 15) Remove the distributor and spark plug wires from the engine. 16) Make one last check for other parts or components that should be removed so that the engine can be lifted out. b. Under-engine preparation for removal 1) Raise the vehicle, if necessary. 2) Drain the engine oil. 3) Disconnect the exhaust pipe. 4) Remove the nuts or bolts attaching the front engine mount rubber insulators to the cross-member. 5) Remove the starter, if necessary. 6) Disconnect the clutch linkage, if necessary. 7) Remove the clutch housing upper and lower attaching bolts. 8) Lower the vehicle, if raised, and support the clutch housing. c. Lifting out the engine 1) Attach an engine sling. If chain is used, place flat washers under the attaching bolt heads. 2) Select a chain hoist or crane with sufficient capacity to lift the engine. 3) Raise the engine slightly, and carefully pull it away from the transmission. 4) Maneuver the engine to raise it from the engine compartment. 5) Support the engine on an engine stand (see following page) or on some other device on the floor. 2. Top End Disassembly a. If possible, attach the engine to an engine stand. b. Drain the engine coolant, if not previously done. c. Drain the engine oil, if not previously done. 1) Inspect the oil for evidence of foreign matter contamination. a) Look for metal, dirt, rubber, sand, or coolant contamination. b) Smell the oil for the presence of gasoline, which will dilute the oil. Eight oz. of fuel in a 5-qt. capacity crankcase will change the oil from 30W to 20W. Dilution will contribute to excessive engine wear. c) Feel the oil for an increase in viscosity. Thickening indicates a higher than normal level of solid contaminants in the oil. Solid contaminants can be tars, gums, lead compounds, or carbon. Such contaminants can lead to clogging of oil passageways. d. Remove the distributor cap and wires, if not previously done. e. Remove the distributor from the engine. f. Remove the spark plugs. 1) Analyze the spark plug condition; record your observations on the engine teardown guide. g. Remove the oil filter assembly, dipstick, fuel pump, and fuel lines. h. Remove the carburetor. i. Drain the fuel from the carburetor, fuel pump, and fuel lines. j. Remove the alternator, thermostat, water pump, belts, and hoses. 1) If you plan on re-using the water pump, store it in water. k. Remove the intake manifold. 1) If the intake manifold is stuck, jar it loose with a piece of wood. Do not use a screwdriver to pry it off, as that may ruin gasket surfaces. 2) Check the gaskets for evidence of water, vacuum, or oil leaks. 3) Shine a light into the valve ports; look for evidence of oil being drawn through the intake and exhaust valves. 4) If possible, inspect the underside of valve heads for a hard carbon buildup. a) If present, this indicates that oil is passing between the valve guides and valve stem. 5) Inspect the intake manifold passages with your finger; look for oil. l. Remove the exhaust manifold. 1) Inspect for broken gaskets and for any casting cracks. m. Remove the valve covers. 1) Look for sludge or any unusual deposits. a) In the first stage of formation, sludge is soft and pasty, and can be easily carried to other engine parts, which may result in clogging of oil lines. b) Once sludge is formed, it may dry out and become converted to grainy "coffee grounds," or hard deposits. n. Remove any rocker arm shaft lubrication delivery pipes. o. Remove, in sequence, the rocker arms. p. Remove the push rods; check for visible defects. Keep them in order! q. Remove the cylinder head attaching bolts in the reverse sequence that they are to be tightened. This is important, to prevent head warpage or cracking. See the manual for this sequence (or spiral in from the outside). r. Lift the cylinder head from the block. s. Remove the valve lifters. 1) If they stick, pull them up as far as possible, then wait until you have removed the camshaft. t. Examine the top of the engine. 1) Check the combustion chamber for cracks, burn-throughs, or other irregularities. 2) Remove the valves and check them for irregularities. 3) Check the tops of cylinders. a) An oily, caked deposit indicates that too much oil is getting into the combustion chamber. b) If the piston head shows "washing" on the edge, excessive oil flow past the rings is indicated. 4) Look at the cylinder walls above each piston. a) Vertical scratches indicate broken rings. 5) Examine the block deck surface for cracks, corrosion around water holes, or other defects. 6) Look closely at the head gasket for problems. a) Burn-through between cylinders or seepage around water holes indicate gasket problems. 3. Engine front disassembly a. Remove the crankshaft snout bolt and washer. 1) Using the proper puller, remove the crankshaft pulley or vibration damper. (Pulley pullers may destroy the balancer if they pull on its outer diameter; be sure the puller grips the center part of the balancer.) 2) Remove and inspect the key from the crankshaft snout; check its fit in the pulley. b. Remove the front (timing) cover. 1) On some engines, the oil pan may have to be loosened or removed first. 2) Check the cover for rubbing-type wear. 3) Check around coolant passage holes. 4) Check for excessive timing chain slack. c. Remove the crankshaft oil slinger; note the direction that it faces. d. Remove any timing chain tensioners. e. Remove the timing chain or belt, if so equipped; examine gear teeth for wear and cracks. f. If possible at this time, remove the crankshaft timing gear with a gear puller; examine gear teeth for wear and cracks. g. If the engine is equipped with a separate fuel pump eccentric, push rod, or driveshaft, remove it now. h. Remove the camshaft. 1) In some cases, it may be easier to remove the camshaft after the connecting rods and crankshaft have been removed. 2) Be extra careful when removing the camshaft, to prevent damage to the lobes or journals. 3) Inspect the camshaft for any obvious defects such as: a) Rounded (worn) lobes b) Edge wear c) Pitting or galling i. Remove the valve lifters, if not previously done. 1) If they are to be used again, the lifters should be kept in order. Always reinstall such used parts in their same locations (to mate with the same part of the mating component). NEVER use old lifters on a new camshaft. 2) Do not install old lifters on a new camshaft. 3) If the lifters are domed (concave on the bottom), they should be replaced. 4. Bottom end disassembly a. Remove the oil pan, if not previously done. 1) Inspect any sediment in the sump and on the intake screen of the pump. a) Iron or steel, in sliver or flake form, generally means adverse wear on camshaft lobes, lifters, timing gears, cylinder walls, piston rings, or push rods. b) Fine iron or steel particles with a uniform grain size are generally from machining operations on parts (which were not cleaned up before installation of the parts). c) Nonferrous materials are generally from bearing or bushings. b. Remove the oil pump assembly including the pump, screen, and driveshaft. c. Check all connecting rod and main bearing caps for correct position and numbering prior to removal. If the numbers cannot be seen, mark each cap. d. Remove the cylinder wall ring ridge, using a ridge reamer. 1) This will prevent damage to the piston when pushing it through the top of the cylinder. 2) Do not remove material from the cylinder below the ring wear line. e. Ensure that each rod and its cap are marked (punched, etc.) for reassembly in the proper location and orientation. Remove one cap at a time, and push the connecting rod and piston assembly out the top of the cylinder, from the oil pan side. Be careful not to allow the pistons to drop on the floor. 1) Put plastic or rubber hose (or tape) over the rod bolts, if they are still in the rod, in order to ensure that they do not scratch the crankpin journals on their way out. 2) Position the crankshaft at bottom dead center (BDC) for that cylinder before removing the assembly. 3) Lightly tap with a hammer handle or wood dowel, if necessary. 4) As the rods are removed, keep the caps and bearings in the proper order. a) Mark the bearing back with the number of the cylinder and the position: 1U, 1L, etc. b) Clean and wipe the bearings dry. c) Carefully inspect the bearing surfaces for defects, wear, or distressed areas. f. Wipe the pistons dry and visually examine them. 1) Look for cracks, scuffing, cracked rings, and bent or broken lands. 2) Inspect the skirt wear pattern for any indication of connecting rod misalignment. 3) Keep the pistons in order. g. Remove the piston pins. 1) Inspect for defects. 2) Keep them in the correct order. h. Wipe the cylinder walls dry. 1) Use a light to help inspect the walls. a) Look for pitting, cracks, and scuffing or scoring. b) Later, the cylinders will be measured for taper and out- of-round wear. i. Remove the flywheel. j. Remove the main bearing caps and lower bearings, and carefully lift out the crankshaft. 1) Store the crankshaft on end to prevent warpage (yes, it does happen). 2) Mark the bearings, and keep them in order. 3) Inspect the main bearings as you did the con-rod bearings. k. Remove the upper main bearings, and bolt the main bearing caps back onto the block, in the correct order and positions. 1) Mark the bearings (if not factory-done) and keep them in order. 2) Inspect the upper bearings. l. Wipe the crankshaft main and rod bearing journals dry, and inspect them for obvious defects. 1) Look for scores, nicks, galling, and ridges. 2) Rub a piece of copper (penny) across the bearing surfaces. a) If the surface picks up copper, the shaft is too rough, and should be reconditioned. m. Remove the main bearing seal from the block. n. Visually inspect the entire block casting for any apparent defects that would prevent reuse. o. Remove the dipstick tube, if it sticks up higher than the block upper surface. p. Remove all front and rear oil gallery plugs. 1) It may be necessary (or easier) to use a drill and an easy- out. q. Remove the camshaft bearings. r. Remove any nonferrous components, if the engine is to be hot-tank cleaned. B. Engine reassembly (assumes repaired and/or replacement parts have been obtained) 1. Check the condition of every stud, bolt, and bolt hole in the block; correct any damage. 2. Blow air through all oil holes in the block in order to remove any foreign matter, dust, grit, etc. 3. Carefully scrutinize the block and head for dirt or other contaminants; clean as required. Use compressed air liberally. 4. Install cam bearings; be sure that oil holes in bearing are aligned with oil holes in the block. 5. Install the camshaft; lubricate the lobes (special cam break-in lubricant) and journals (grease) before installation. 6. Install the upper portion of the rear main oil seal on the crankshaft bore. (Engine block should be upside-down at this point). Install the lower portion of the rear main seal in the rear main cap. 7. Place the main bearing inserts in the block, and in the main bearing caps. a. Be sure that the thrust bearing is installed in the proper location. b. If each bearing pair has a hole in only one insert, make sure that the inserts with the oil hole are placed in the block (to match with the block's oil gallery hole). 8. Thoroughly lubricate (grease) the rear main seal and all bearings. 9. Gently lay the crankshaft into position on the main bearings. a. Be careful not to damage the bearing inserts when placing the crankshaft. b. It's a good idea to clean the crankshaft one last time immediately prior to installation. 10. Install the rear main bearing cap (with seal) first. Do not tighten. a. Install remaining main bearing caps and tighten fasteners finger tight. b. Check to be sure that all bearing caps are installed at the correct position; they should be numbered, except for the rear cap (it's pretty obvious where and how it fits). c. Seat the crankshaft by tapping each cap lightly while rotating the crankshaft. 11. Using a mallet and a wood block, tap the crankshaft back and forth endwise in order to seat and align the thrust bearing. 12. Tighten the main bearing caps to the torque specifications in the technical manual. a. After tightening each bearing cap, turn the crankshaft to be sure that it turns freely. Note that there will be some drag from the rear main seal; disregard, unless it seems abnormally large. 13. Measure the crankshaft end play; compare with specifications. 14. Install cam timing components (front end of engine). a. There may be gears, chain, and sprockets, or even belt and sprockets. b. Ensure that the relationship between crankshaft position and camshaft lobe position is correct. 1) Timing gears generally have punch marks; consult the technical manual for location and proper orientation of timing marks. 15. Install the bottom (oil) ring on each piston. a. First install expander, then bottom scraper, then top scraper. b. Generally, these can be installed by hand; they're quite flexible. 16. Install the second or middle (compression) rings. a. If the ring is marked, install the ring with the mark up. b. Do not mix up middle rings with top rings; they are often slightly different, and easily confused. c. Use a ring expander! Compression rings will easily break. 17. Check the end gap of the top ring in the cylinder; compare with specifications in the technical manual. 18. Install the top ring on each piston. a. If the ring is marked, install it with the mark up. b. If not marked, install with the inside chamfer up. 19. Place the lower bearing inserts in the connecting rod caps. a. Thoroughly clean the bearing backs and bearing seats before installation. b. Snap the bearing into place; it should hold itself in. 20. Place the upper bearing inserts into the connecting rod. a. Use the procedure as in "S" above. b. If the rod has a squirt hole for lubricating the cam, be sure the bearing insert hole aligns with the squirt hole in the rod. 21. Lubricate (grease) the bearing surfaces in the rod and its cap. 22. Stagger the piston ring gaps. a. Do not position any ring gap in line with the wrist pin hole. b. Do not position any ring gap over the piston thrust surface (i.e., perpendicular to [90ø from] the pin hole). c. Do not position any ring gap directly above another ring gap; make the compression rings' gaps as far apart as possible. 23. Install the piston/rod assembly. a. Important: If the rods have bolts in them, place a short piece of plastic or rubber hose (or tape) over the connecting rod bolts in order to protect the crankshaft journals from nicks and scratches during piston installation, and to aid in guiding the rod onto the journal. b. Dip the top of the piston (above the piston pin) in clean oil. c. Clamp the ring compressor around the piston and rings. d. Position the crankshaft at bottom dead center for that cylinder. e. Check the reference ("front") mark on the piston head, to ensure that the piston will be properly positioned in the cylinder. Also check to see that the rod lines up correctly with the journal. f. Using a wooden or rawhide hammer, push the piston into the cylinder, until the top ring is just inside the cylinder; then set aside the ring compressor. NOTE: It may be necessary to tap LIGHTLY on the top of the piston. If excessive force is required, STOP and determine the cause. g. Push the piston and connecting rod into the cylinder until the connecting rod seats on the crankshaft. Guide the rod onto the crankshaft journal, rotating the piston as necessary to obtain perfect alignment. Be sure the bearing insert did not fall out. 24. Install the rod cap. a. Remove the tubing or tape which was covering the rod bolts, and clean and lubricate the threads. b. Install the cap (finger tight), making sure that it faces in the correct direction (matches the rod; note reference marks), and that no foreign matter is on the bearing surfaces. c. Tap the cap lightly to seat it, while holding the piston in place. d. Torque the fasteners to the specified value. 25. Install the oil pump and related parts, such as pickup tube and drive rod. 26. Gasket Installation a. Head gasket - Never reuse a head gasket. 1) Install in the proper orientation. a). Look for markings indicating top, front, or this-side-up. b) If no such markings are present, install the gasket with the stamped identification numbers toward the head. 2) Check for proper gasket (holes in the right place), on both the head and block decks. a) Water holes in the gasket may be smaller than those in the block or head. Some holes may be plugged in the gasket; this is not unusual. 3) Use compressed air to blow out all head bolt holes in the block. 4) Clean head bolt threads; apply sealant (if required), light oil, or antiseize compound to the threaded portion. 5) Install the head gasket and the head. Torque the head bolts, in the proper sequence, according to operator's or technical manual instructions. 6) Teflon coated head gaskets are available, which offer a better seal than plain metal, and do not require retorquing or gasket sealer. b. Intake and exhaust manifold gaskets 1) Installation: a) Check the deck surfaces for warpage, and the gasket for fit. b) Use compressed air to clean out all bolt holes. c) Clean fastener threads; apply sealant (if required), light oil, or antiseize compound (especially exhaust bolts) to the threaded portion. d) Apply an antiseize compound to the deck surface for the exhaust manifold. e) Place the gasket. f) Install the manifold. Torque the fasteners, in the proper sequence, according to operator's or technical manual instructions. c. Other gaskets 1) Use sealant (or don't) as recommended in the technical manual. Generally, silicone-based, room temperature vulcanizing (RTV) sealants are appropriate for water or oil seals, but NOT for gasoline seals (i.e., silicones are good for thermostat or timing cover, but not for intake manifold- to-head area or carburetors). 27. Complete the assembly by installation of other engine components such as lifters, heads, oil pan, distributor, manifolds, carburetor, etc. Such items as distributor and carburetor might best be installed after the engine is mounted in the vehicle in order to avoid damaging the components during engine installation. C. Engine Break-in After Overhaul 1. Put the proper amount of the recommended oil in the engine. 2. Be sure that the engine oil pressure gauge is functioning. Some engines can be prelubricated by removing the distributor and driving the oil pump by hand or with an electric drill, before starting the engine. This is a desirable practice, and it gives a good chance to check the oil pressure gauge as well. 3. After first starting the engine, let it run at a fast idle (1500-2500 RPM) for at least 20 minutes. DO NOT IDLE the engine for the first few minutes; the speed is necessary to ensure adequate lubrication during the critical initial break-in period. 4. Check for: a. Normal and steady oil pressure b. Unusual noises (knocking), vibration, or odors c. Coolant, oil, or fuel leaks d. Exhaust sound and leaks e. Obvious compression leaks f. Vacuum leaks g. Exhaust color and smell 5. If the engine has knocking sounds or excessive vibrations, or the oil pressure is not reasonable and steady, shut the engine off immediately and determine the cause. 6. After the initial fast-idle beak-in, let the engine idle, and check: a. Throttle response - any hesitation? b. Recheck/reset ignition timing and carburetor adjustments. 7. For the first few hours of operation, the loads on the engine should be held to moderate levels, and engine speeds should be varied from idle to mid-range. Gradually introduce the engine to full service. 7/15//91 JWR/RRE/tf #%&C