How to Rebuild an Engine

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This how to guide is designed to explain the process involved in rebuilding a engine. This is a very intense and complicated process which I do not recommend be taken on by anyone who is not a professional.

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Step 1: Engine Block Inspection

1) Perform a visual inspection of engine. Inspect fluid sweeping out of core plugs. Inspect the water pump for leakage. Inspect the Harmonic Balancer for cracked rubber. Check for any signs of overheating. Check for any excessive gasket sealer left behind from previous work.

2) Check the ID and casting numbers. This is to ensure that the engine you think you are working on is actually the engine you are working on. Engine swaps are semi-common now a days and each engine has different specifications.

3) Remove the ridge on the cylinders. The ridge is defined as the point where rings meet bore.

4) Inspect the external components on the engine. Inspect the distributor for wobble & looseness. Inspect the alternator belt, spin the pulley and listen for any unusual noise. Inspect the clutch assembly for wear.

5) Remove the oil pan.

6) Remove valve heads.

7) Remove piston and rod assemblies. After removing the caos from the rods, place rod journal protectors on the Rod bolts to prevent them from scoring the engine block during removal. Once removed put the caps back on rods, keep them as a paired set.

8) Remove and inspect the crankshaft. Once removed store in a safe place, preferably use crank mounting plates so that you can accurately measure the crankshaft. Keep old main bearings in order, inspect them for wear and excess dirt. With the crank removed and stored correctly place the main caps back on the engine block and torque to specification.

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Step 2: Crankshaft Inspection

1) Perform a visual inspection of the crankshaft. Inspect for cracks and any signs of overheating.

2) Measure different crankshaft dimensions. These dimensions include journal diameter, out of round, taper, and run out. If the crank is out of spec mark it for identification and have it sent to the machine shop. Once the machine shop has reground the crank use a rifle brush to remove the excess debris from the oil passages. Then measure the crankshaft again so that you can replace the bearings to get the crank to bearing clearance within specification.

3) Replace the pilot bearing

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Step 3: Engine Block Inspection 2

1) Remove the camshaft, balancer shafts, and auxiliary drives. Pay attention to end play shims and spacers, keep these organized you will need to put these back in the correct order. Remove bearings, pay attention to their position.

2) Remove the core plugs, brackets, guide pins, and everything else still attached to the outside of the engine block.

3) Perform a visual inspection of the engine block for any cracks.

4) Magnaflux the engine block. Magnaflux should only be used to find leaks on cast iron and steel only. Use dye penetrant to find cracks on aluminum blocks.

5) Using a straight edge and a set of feeler gauges check the deck surface for flatness. Measure the both diagonally and horizontally. If the deck surface exceeds the specification for flatness resurface the block. Use caution when resurfacing not to remove too much material. If too much material is removed you risk having the pistons collide with valves.

6) Using a dial bore gauge measure each cylinder bores taper and for out of round.

7) Inspect each cylinder for discoloration and washboard. Use a rigid stone hone to identify washboard.

8) Check alignment and out of round of the main bearing bores with a dial bore gauge.

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Step 4: Valve Head Disassembly

1) Use a valve spring compressor to compress the valve spring.

2) With the valve spring still compressed remove the valve keepers.

3) Slowly release the valve spring out of compression. Once you can remove the compression tool, remove the valve springs and shims. Keep these components in order.

4) Remove the valve from the head, do not force it out as it may score the guides. Repeat these steps until all valves have been removed from the valve head.

5) Remove any carbon buildup or dirt from valves and valve head. If possible have the head shot peened or glass beaded.

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Step 5: Valve Head Inspection

1) Use magnaflux or dye penetrant to find any cracks.

2) Check the valve head for flatness. Note any flatness which is out of specification so that it can be corrected after inspection.

3) Inspect the guides for excess wear using a dial indicator.

4) Check for recession of the valve seats

5) Check for worn valve stems is a micrometer. Replace any valves whose stems exceed specification

6) Check for worn keeper grooves. Replace any worn keepers.

7) Check the thin margins on the valves. Margins are thinner on intake valves than exhaust valves. Replace valves with excessively thin margins.

8) Measure the valve springs free length, tension, and squareness. Replace any springs which are worn beyond specification.

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Step 6: Valve Head Reconditioning

1) Recondition the worn valve guides

2) Replace the recessed valve seats

3) Reface all valves which are not going to be replaced.

4) Machine the valve seats.

5) Lubricate the valve stems with engine oil.

6) Install valve seals. The valve seals come in 3 different types: band, umbrella, or PC type. Pay attention to the order of assembly.

7) Assemble valve heads.

8) Check for leaks using either a liquid test or a vacuum test.

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Step 7: Engine Block Reassembly

1) Clean block using soapy water, then air dry.

2) If the block was machined, recheck all the dimensions. Machine shops do make mistakes, its your job to double check their work.

3) Check ring end gaps and oil clearances.

4) Wash block again using hot soapy water, then blow dry.

5) Blow out all bolt holes using compressed air to remove any debris prior to installing fasteners.

6) Install oil gallery plugs and core plugs using hardening sealer. Never use silicone sealer.

7) Grease the camshaft bearing with high pressure grease, then install camshaft.

8) Clean and dry main bearing bores and backs of bearings. Lubricate the inside of all the main bearings and the lip on rear main seal.

9) Then install main bearings and rear main seal, be sure install in the correct position, they are position sensitive.

10) Install crankshaft and main caps. The caps are sensitive to position and direction. Torque the caps onto the block from center out in 3 stages.

11) Rotate crank to ensure it is not binding. If the crank rotates smoothly check end play.

12) Install the timing chain to specification; be sure to align the timing marks.

13) Degree the cam.

14) Stagger ring end gaps on pistons (This means that the tiny gap caused by the ends of each ring are 180 degrees apart, this will reduce blowby. Be sure oil expander is butted.

15) Using rod journal protectors and install the piston and rod assemblies. Install and torque rod caps as you while installing the rods, torque these in 3 stages to ensure that they seat properly.

16) Rotate crank after installing each piston to make sure it still rotates freely.

17) Install head gasket (the gasket may be directional, be sure to install in the correct direction.

18) Install the valve heads . Lube the bolt threads with OEM lubricant or sealer, then torque the bolts down in 3 stages using OEM specified pattern (Pay attention to length and location of bolts).

19) Install valve train, be sure to lubricate the parts as you install them.

20) Adjust valves as necessary (minimum up/down movement, then torque 3/4 turn)

21) Install the rest of pans, covers, pulleys, ect...

22) Paint as required

23) Double-check everything

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