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Engine Rehab
By Mike Bumbeck/autoMedia.com
Printable version
Degree of DifficultyDifficult
Difficult
Estimated Time300 minutes
300 minutes
Step 1 - A static compression check is the first step to finding out what's right or wrong inside the engine. In this case, one cylinder had low compression and the timing chains were making an unnerving racket. The engine had logged over 100,000 miles. The decision was made to yank it out and put it on an engine stand to see what was going on.
Static Compression Check is First Step in Diagnosing an Engine
Step 2 - Before yanking the engine, spend a good deal of time taking "before" pictures and labeling all electrical connectors, vacuum lines, and any other easy-to-forget things while still together. Park the car where it doesn't have to move for a while. Wheel chocks will prevent any unwelcome rolling.
Take 'Before' Images and Stablilize Vehicle Before Removing Engine
Step 3 - Follow the procedure outlined in the manual for engine removal. Get some one-quart plastic bags. Label them Starter. A/C. Intake Manifold. And so on. Use the bags to store nuts and bolts. Mark the hinges for reference and remove the hood. Use the hoist and a chain to remove the engine from the car for transfer to the engine stand.
Follow Users' Manual When Removing Engine
Step 4 - With the engine on the stand, begin disassembly and inspection. Remove the cylinder head or heads. Remove the oil pan, harmonic balancer, timing cover, and any other external parts. Take more photos as you go for future assembly reference. Keep bagging bolts by sets.
Begin Disassembly and Inspection
Step 5 - Now it's time to remove the engine internals. Flip the engine over and remove the connecting rod nuts and caps. Any stubborn connecting rod or main bearing caps can be convinced a tapping with a plastic faced hammer. Never strike bearing caps with a metal hammer.
Remove Engine Internals
Step 6 - Thread a bit of rubber hose over the ends of the connecting rod bolts so they don't nick the crank journals on the way out of the engine block. Remove the pistons and rods by pushing them through the cylinders from the bottom.
Protect Connecting Rod Bolts
Step 7 - Marking parts is of vital importance. Everything has to go back together exactly the same way it came out. Use a punch set to mark and index main caps, connecting rods, and any other parts not marked. Keep bearings together and mark backside with a sharpie.
Marking Parts is Very Important
Step 8 - Remove main caps and bearings. Remove the crankshaft. Inspect the bearings and crankshaft journals for uneven wear, scoring, and anything other than smooth. Scoring on journals that can be felt with a fingernail means the crank has to go out to the machine shop. Black carbon on journals or bearings is a very bad sign.
Remove Main Caps, Bearings and Crankshaft
Step 9 - Inspect the engine by reading its parts and surfaces. Excessive vertical scoring on the cylinder walls or molten pistons are sure signs the engine block will have to be sent out to the machine shop. This Mitsubishi G54B turbo engine still showed factory crosshatch finish hone on the cylinder walls after 100,000 miles.
Inspect the Engine by Reading its Parts and Surfaces
Step 10 - Further cleaning of pistons in a chemical dip will remove carbon deposits for a closer look at piston ring condition. All told this engine looked like it could get by with some new timing chains, fresh pistons and rings, and a set of bearings. A new cylinder head will also be part of the rebuild. We'll make all it all happen over the next few installments.
Cleaning Pistons in a Chemical Dip Will Remove Carbon Deposits for a Closer Look
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