Q: How do you remove the pistons in the engine while the engine is in the car?

Hi there. You will have to remove the timing belt, exhaust manifold, intake manifold, all vacuum lines, the cylinder head, and the oil pan to gain access to the piston removal. Drain out all of the oil from the oil pan and remove the oil pan to locate the piston rod bolts or caps nuts. Then remove the piston rod caps one at a time. (Do not mix up the caps to the pistons for it will bind up in the engine). Once the cap is off the rod, then push the piston up through the bore and out the top of the engine. Stamp the rod and cap with the corresponding order number that it was taken from, like cylinder 1, 2, 3, 4. Then remove the piston rings and break the fire ring in to pieces. Use the broken ring to clean the ring groove and clean out the carbon deposits. Then put the piston in a cleaner and clean the piston up. Then you can install the new rings on the piston. Then you will have to install the piston into the engine with a ring compression tool (tool that compresses all of the rings on the piston) and use a handle to a hammer to install the piston. Put on the cap to the piston with new bearings. Make sure that you put some motor oil on the bearings before you install the cap to the rod. Torque to rod cap nuts or bolts to the manufacture specs. Then do the same for the other pistons. Then you will need to clean off the deck of the engine (where the head gasket sits) and put a new head gasket on before installing the cylinder head. I recommend checking all of the valves and valve guides on the cylinder head before putting the head on the engine block. Make sure that the old head gasket, exhaust gasket, and intake gasket is removed from the cylinder head before putting the head back on. Then put the head on and align up the timing to the crank shaft. Hook up the timing belt or chain and then put the oil pan on. Make sure that the intake, exhaust, and all of the brackets and vacuum lines are hooked up and tight. Then put new oil in the engine with a new oil filter. Crank the engine over, but do not start the engine to build up oil pressure. Then start the engine. Make sure that the engine has good oil pressure as its running. If you need further assistance with replacing the piston rings in your engine, then seek out a professional, such as one from Your Mechanic, to help you.