How to Pull the Pistons in a Car

Piston removal is all about organization and patience.

Even under the tamest conditions, pistons are subject to loads of mechanical and thermal stresses. Removing one or more for replacement is no simple task, one in most cases requiring complete removal of the engine. Although you may technically be able to replace a piston without removing the engine, odds are that you'll want to remove the engine anyway just to clean it and check for further damage. Procedures will vary greatly from vehicle to vehicle in terms of both engine and piston removal.

Things You'll Need

• Full set of standard and metric sockets
• Full set of Philips and flathead screwdrivers
• Engine hoist and hardware
• Floor Jack
• Jack Stands
• Two foot length of one inch diameter wooden dowel
• Plastic deadblow hammer
• At least two 3 inch lengths of 3/8 inch rubber fuel line

Instructions

Removing the Engine

1. Disconnect all electrical harnesses, belts, fuel lines, cooler lines, sensors, control cables and linkages from engine. Label each harness connector removed with a piece of masking tape and permanent marker to ease engine re-installation.

2. Remove cooling fans and radiator to prevent damage to core, and remove hood to ease engine removal.

3. Unbolt air conditioner compressor from engine and lay it off to one side without disconnecting the hoses. This will allow you to avoid venting refrigerant into the atmosphere and paying to refill it.

4. Attach engine hoist to dedicated engine lift points as recommended by your manufacturer. Place a small amount of pressure on the engine by engaging hoist before unbolting any mounts; this will prevent dangerous engine movement during removal.

5. Unbolt torque converter from flex-plate, remove transmission housing bolts and carefully remove engine mount bolts. Many times removing the engine and transmission together (especially in front-wheel drive applications) will make for a far simpler removal and re-installation.

6. Engage engine hoist and slowly lift engine free of car, avoiding (if possible) sending it flying through your windshield or radiator core support. Carefully lower engine onto a stable work surface or attach it to an engine stand if you have one and have opted to remove the transmission.

Removing the Piston

1. Remove (in this order): the intake manifold(s), valve cover(s), anything attached to the cylinder head including brackets, sensors, timing chain/belt, and finally the cylinder head(s).

2. Flip the engine over and remove the oil pan.

3. Identify the affected piston's connecting rod where it attaches to the crankshaft, and rotate that crankshaft so that rod's associated journal stops as far away from the engine block as possible. (This isn't strictly necessary in most cases, but will help increase clearance and prevent damage to the crankshaft journal during removal.)

4. Remove the connecting rod nuts/bolt, and carefully brace the wooden dowel rod against the bottom of the piston. Tap the wooden dowel with your deadblow hammer to push the piston through the cylinder and away from the crankshaft. Stop tapping once the rod cap falls free and the rod studs rest against the crankshaft journal.

5. Slip the fuel line tubing sections over the connecting rod studs to keep them from nicking the crankshaft. Continue tapping the dowel rod until your piston falls out of its cylinder bore.

Tips & Warnings

• This is a very basic outline for piston removal, but expect a few surprises. Overhead-cam cylinder heads, "flat" configured engine blocks (like those used by Subaru and Porsche), all wheel drive systems and variable valve technologies (like Honda's VTEC and Mitsubishi's MIVEC) will all add layers of complexity to this procedure.

References

• VR4 Stealth: Pulling the Engine
• Tomorrows Technician: Piston Replacement
• Integrated Publishing: Inspecting, Maintaining and Replacing Pistons

Resources

• Business Ideas Profitable: Removing the Pistons from a Small Block Chevy