More than one auto restoration back yard expert has had some difficulty and difficulties in installing piston rings in older vintage and classic Chevrolet vehicles. You would think that this procedure would be standard like “fixing a Chevy” and not like current vehicles that are all so high tech electronics and cramped to work on. However this repair and renewal procedure and set of procedures is not without its challenges to the backyard mechanic and want to be vintage or classic auto restoration expert. To begin with the pistons themselves must be cleaned of gunk and debris, the rings removed and ultimately the pistons themselves must be carefully inspected.

To begin with after the connecting rod and piston assemblies are removed from the engine, they should be thoroughly cleaned in a solvent designed for cleaning engine parts. If such a special solvent is not available, standard kerosene can be used; however it is not nearly as effective as commercial cleaning solvents. After the disassemblies have been cleaned, the rings can be removed as they will not be used again. The usual practice is to grab the end of the ring with a pair of pliers and pull out. In the case of cast iron rings, this will break the ring so that both parts are easily removed from the groove. Steel rings are removed in the same manner but instead of breaking, the ring can be easily worked out of the groove and once one end is free, the rest will easily spiral out of the grooves. Always be sure to remove the steel expander ring from the bottom of each groove, where such rings are used. Then with the rings removed from each piston, the groove can be thoroughly cleaned. The preferred method of cleaning is to use a special ring groove cleaning tool. Such tools quickly cut the carbon from the groove without danger of scratching or damaging the sides of the ring groove.

If such a tool is not available, a substitute method is to use a broken segment of a cast iron piston ring. This is basically used as a scraping tool. However this method is inefficient and is long and tedious. In addition there is also the chance and possibility of marring the surface of the sides of the ring grooves. As a result when placed back into the cylinder they, the result could be loss of compression and also increases in motor oil consumption.

It should be pointed out that if new piston rings are fitted, that the standard at the time, when these autos were the current models “on the roads of America and Canada” that most shops did not even bother to clean the piston and rod assemblies. Instead they sent them to an automotive machine shop to clean the assemblies, and install new pistons and rings. Or, if desired, the ring installation could be left if you wish, to the mechanic doing the actual overhaul job. In general, when new rings are found to be necessary, it is always advisable to install new piston rings at the same time concurrently. The reason being that pins generally wear out about the same time as rings do.

Before installing new rings on the pistons or fitting new piston rings, the pistons should be carefully checked to ensure that they are in good condition and are still serviceable. In addition the difference in diameter between the pistons and the cylinder wall should be checked. In the automotive trade this was known as “piston clearance”.

When examining the piston, make sure that the ring grooves are in good condition, that the sides of the grooves are smooth, and without any groove worn by the rings. The sides of the grooves must be at right angles with the center line of the piston. A good method of checking the grooves is to roll a new piston ring around the groove. It should roll freely without binding, but also without any “side play”. If the clearance between the side of the ring and the piston groove exceeds .005 inches, then the piston itself should be discarded and a replacement substituted. However if desired the pistons can be placed in a lathe, and the grooves trued. A spacing ring is then inserted to compensate for the amount of metal removed from the side of the groove. Note when checking pistons; make sure that there are no burned out areas around the ring lands. In addition, make sure that there are no cracks. If the piston is of the steel strut type variety, make sure that the strut has not itself come loose.

Lastly in terms of inspection of the piston itself. Spongy eroded areas near the top of the pistons are usually if not invariably caused by detonation or pre-ignition. A shiny surface on the thrust surface of the piston, offset from the center line between the piston pin holes, can be caused by a bent connecting rod. Replace pistons that show signs of excessive wear, wavy “ring lands”, fracture and / or damage from detonation and pre-ignition.

Author Bio: T. Z. Cole Used Trucks Vancouver BC Fort Mc Murray Car Dealers Auto Sales Vancouver Canada