How to Install Piston Rings

April 5, 2012

Piston replacement often requires new piston ring installation as well. Learn how to install piston rings yourself.

Piston Rings

Learning how to install piston rings is a step by step process. First step for installing piston rings is to remove the pistons from your engine. Typically, this is done only when you are in the process of a complete engine rebuild or when you installing new pistons. There is never a time in which you would remove your pistons just for the sake of installing new rings. Here is how you do it.

Remove the Old Rings

Work in a well-lit area so you can properly see what you're doing. Remove your old piston rings with needle nose pliers. This step is fairly easy and can be done in no time at all.

Clean the Grooves

Your piston has three grooves in which the rings sit. Two of these grooves are for compression rings and the third is for an oil control ring. In order to properly install the rings, you first need to clean the grooves. It is very important that the piston be as tight as possible when installed. Remove any debris inside each groove with a scraper or an older piston ring. Make sure each groove is free from dirt and grime before continuing.

Lubricate the Rings

Using engine oil or transmission fluid, lubricate the new rings. This will aid you during the installation process.

Install the Rings

Starting with the oil control ring, install your rings into their grooves. Insert the oil control ring into the groove closest to the bottom of the piston. Slide the lubricated ring over the head of the piston and work it downwards until it is in the proper location. Next, install the compression rings. The first compression ring sits in the middle slot. When you slide this one into position, align the gap in the ring 180 degrees from the gap in the oil control ring. Last, install the top compression ring, aligning the gap 90 degrees from the gap in the previous ring.

Compress the Rings

Compress the rings towards the sides of the piston. This allows the piston to slide into place in an easier manner.

Lower the Piston into Place

Lower the piston down through the cylinder into its proper place. Do this by releasing the piston rod, lowering it into position. Gently tap the piston until it slides into the proper place. Now your rings are installed on the piston, and the piston is installed in your engine.

The Role of the Piston

Knowing how the piston works in the engine means you understand much more about the engine. It's worth learning about the pistons to know what can go wrong, too.

Compression

In all internal combustion engines, the piston compresses the mixture of air and fuel. The two substances are in a specific ratio. As the piston goes down within the cylinder, the air and fuel enter the chamber. As the piston rises again, what's called the power stroke, the air and fuel are compressed by the piston. The closer the piston is to the head of the cylinder, the more compressed the fuel and air become. At the top of the stroke the mixture is ignited by the spark from the spark plug.

Vacuum

As the piston is forced back down by the explosion it creates an area of low pressure within the cylinder, producing a vacuum. That's what pulls the mixture of air and fuel into the cylinder for the next power stroke, when it will be compressed and then ignited.

Power

Connecting rods attach the piston to the crankshaft and convert the up and down motion of the piston into circular motion. The crankshaft turns and transfers power to turn the wheels.

Wear

Over time, the pistons wear down and the piston rings need to be replaced. It's vital that the pistons fit snugly within the cylinder in order to create both the proper compression and vacuum. If that doesn't happen, you won't achieve a good spark and the engine won't operate efficiently.

Material

A piston will most commonly be made from aluminum due to its light weight. The cylinder itself is made of iron. Aluminum is strong enough for pistons, with a material like silicon used as an alloy. It needs to be resilient because the operating temperature at ignition in the cylinder is 650 degrees Fahrenheit.

There are other alloys used in pistons for performance engines. In performance engines the piston will usually be heavier and thicker, especially in the 2618 performance piston, which uses less than 2 percent silicon as an alloy.

5 Considerations for Installing Aftermarket Pistons

For anyone carrying out restoration work on their car, there are a number of things to consider before installing aftermarket pistons. Before you install new pistons, you should make sure the modifications you are going to make are right for your car.

Your Warranty

Before you consider installing any car parts, make sure this won't invalidate your car's warranty if you have one. Be aware that although some aftermarket parts are legally available, they may not be legal to install.

Forged Pistons

Some aftermarket pistons differ greatly from those supplied by the original equipment manufacturer (OEM). If you are driving your vehicle on a daily basis, choosing forged pistons is probably not the right choice for you. Forged pistons are intended for race engines that are checked and maintained on a regular basis. Although they are lighter and stronger than regular pistons, they require a looser clearance between the cylinder wall and the piston itself. The extra clearance is good for high horsepower cars and intense driving, but you will experience increased blow, and ultimately more wear on the cylinders.

You may also experience an audible piston slap if you have installed forged pistons. This is when the pistons move against the cylinder wall when the engine is warming up. It is caused by the greater clearance and will create more wear on both the pistons and the cylinders.

OEM Pistons

If forged pistons are not for you, you may wish to install pistons made by the OEM. These are often used in road racing and auto cross and are more appropriate to use in street builds. OEM pistons are reliable and have a better sealant quality than forged pistons. OEM pistons are usually cast rather than forged. They are usually made only in specified sizes, as they are expensive to manufacture.

Brand

Once you have decided which type of piston is right for you, select a brand that is right for your car. If you are purchasing forged pistons, look for brands that have experience and reliability, such as HKS, Wiseco and Cosworth. They should be able to advise you which specifications will be best for your vehicle and the type of performance you can expect. If you are looking to purchase cast pistons for street builds, you probably want to look to the OEM. They should be able to provide you with the required pistons that will improve your performance and are compatible with the car.

Compatible Parts

The final thing you need to consider is if there are any other parts that will need replacing at the same time. For instance, you may wish to replace the connecting rods. In which case, you need to make sure that all the new aftermarket parts are compatible.

Related Questions and Answers

How Does a Piston Ring Compressor Work?

If you're going to be doing a lower engine rebuild, you're going to need a piston ring compressor tool in order to get the pistons back into the cylinders. Because piston rings are designed to ride loosely on the pistons, and when uncompressed, are actually a bit larger in diameter than the cylinder opening. The basic operation of a piston ring compressor is to slide it over the piston and rings, and then either squeeze the handle pliers style, or rotate a worm screw. By doing this, you will be shrinking the diameter of the tool and the rings enough, so that the piston will fit into the cylinder. To see a piston ring compressor in use, click here.

What Is the Most Durable Piston Ring Material?

When you're diving into a high performance engine rebuild, piston ring material is going to be something your parts guy will talk with you about. For most applications, regular steel rings will work great, especially if they are coated with molybdenum, a metal plating material that is very slick. However, in high performance applications, regular steel is too brittle to withstand the torture your engine is going to put them through. You're going to want ductile steel piston rings, coated with molybdenum. These rings will withstand anything your engine will throw at them and keep going for quite a long time. This is what race engine builders use.

What Materials Are Needed for Replacing Piston Rings?

When replacing piston rings, you're going to need a few things tin order to be able to finish the job properly. First and foremost, you're going to need a lubricant to allow the pistons to slide down the cylinder bores during installation. Some people will tell you to just use regular oil. That's not slippery enough and will be wiped off by the lower compression ring. Use assembly fluid. It works better. You'll also need a piston ring compression tool in order to get the expanded rings on the pistons to fit into the cylinder bore. You will also need a set of wrenches and a ratchet with sockets. You should also consider new piston rod bearings as well.

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