Piston Ring Compressor Pliers, What Are They?

It is easy to think that piston ring pliers and piston ring compression pliers are one and the same, but they are not. If you have been in the trade of rebuilding engines for some time, you likely know that these two types of pliers serve different purposes.

In this article, I discuss how to use piston ring compression pliers and highlight their differences from piston ring installation pliers. I will also suggest some of the best piston compression pliers available in the market in case you are looking for an inexpensive tool to compress piston rings when rebuilding a combustion engine.

As you are probably aware, piston rings sit loosely on the piston ring grooves. This causes them to have a wider diameter than the cylinder bore. Consequently, when putting the piston assembly back into the cylinder, you must squeeze the piston rings to enable the piston to smoothly fit into the bore.

There is a variety of tools you can use to put pistons back into an engine. These tools compress piston rings so that the piston can slide into the bore. They include homemade setups, adjustable compressor bands, and fixed-size piston ring compressor sleeves among others.

But the most common tool among many mechanics and DIY enthusiasts is the piston ring compressor pliers kit. The kit typically contains multiple ring compressor bands of different sizes and ring compression pliers.

What Are Piston Ring Compressor Pliers?

piston ring compressor pliers
Piston ring compressor band pliers

Piston ring compressor pliers are the tool you use to manipulate the piston ring compressor bands. These pliers clamp onto the tabs of the compressor bands, allowing you to pull them together and compress the rings on the piston. This enables a ringed piston assembly to go back into the cylinder head more easily.

Piston ring band pliers have a striking similarity to hose clamp pliers. These two types of pliers are so much alike that some individuals use them interchangeably. But while these pliers have many similarities, their grips differ slightly. Therefore, you should not interchange them unless it is absolutely necessary.

Piston ring compression pliers vs Piston ring pliers

As the names may imply, both of these pliers are for manipulating piston rings but differently. Piston ring installation pliers, commonly referred to as piston ring pliers, are for putting compression rings on the piston. These pliers are also known as piston ring expanders because they expand compression rings to fit them onto the piston. You can learn more about piston ring installation pliers in this article.

Piston ring compression pliers, as I have discussed above, manipulate piston rings by compressing them while they are on the piston. This is to enable the piston to fit into the cylinder. These pliers do not work alone. They are used together with ring compression bands. In essence, the work of piston ring compression pliers it to squeeze the compression bands that in turn compress the rings on the piston.

How to Use Piston Ring Compressor Pliers to Install a Piston

Using piston ring compressor pliers to put a piston back in the engine is a straightforward process. You can accomplish it in these 4 simple steps. But first, make sure the rings sit well in the piston grooves as per the repair manual. Also, ensure both the piston assembly and bore are clean and free of dirt. You can also apply some lube on them although you will be applying more oil during the installation process.


Step 1: Put the piston ring compressor band around the piston

Pick the correct size compressor band for the cylinder bore and wrap it around the rings on the piston. Make sure the band stick out about an inch above the piston head or crown. Also, ensure that the gap in the band doe does not align with the piston ring gap(s).

Step 2: Clamp the ring compression band with piston ring pliers

Open the compressor pliers and attach them to the tabs on the compressor band.

Step 3: Clinch down the compression band with piston ring compressor pliers.

After gripping the compression band tabs firmly, squeeze the ring compressor pliers handles to pull the ends of the compression bands together. Squeeze the pliers until the band cannot adjust anymore.

Step 4. Apply engine assembly oil on the cylinder wall and on the edge of the piston

While squeezing the pliers with one hand, apply a liberal amount of regular engine oil or assembly oil on the sides of the cylinder wall and on the edge of the piston head. The oil will enable the piston to slide smoothly into the bore without damaging piston rings.

Step 5: Insert the piston end into the cylinder bore

Gently guide the end of the piston into the cylinder bore, being careful not to scrape the walls or damage the piston rings. This will leave the part of the piston with the compression band sticking outside the cylinder.

Step 6: Tap the rest of the piston into the bore

Gently tap the piston head with a rubber mallet or non-metallic hammer handle to drive the part of the piston with rings further into the bore. Keep the compressed band aligned with the bore and make sure it sits flat against the block to keep the rings from popping out.

But if by any chance a ring pops out before entering the bore, repeat the process lest you break the ring. Also, if the piston can hardly move into the bore after tapping, it means the band is too tight. Let it loose a little bit by releasing some pressure on the compression pliers and try tapping it again. You can also squirt more lube on the edge of the piston crown. If you do everything correctly, the piston should slide gently into the cylinder bore in a few taps.

Step 7: Remove the piston ring compression band and pliers.

After successfully installing the first piston into the cylinder, move on to the next piston. Otherwise, clean the tools, lube them, and keep them safe in the storage box for the next engine rebuild.


There you have it! A piston ring compressor tool is what you need to put piston rings in a cylinder. So, the next time you have an engine rebuild project, dont just look for piston ring installation pliers, get a piston ring compressor pliers set as well. It will save you time installing pistons into the cylinders and could prevent potential damage to the piston rings and cylinder wall.

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Julio a.k.a Pliersman is the owner and creator of the Pliersman Website. A blog that informs and educates you about different types of pliers and their uses. Julio is a handy person and has used a variety of pliers including general-purpose and specialty pliers to accomplish tasks. He holds an electrical engineering degree and has previously worked as an O&M manager for minigrids where his love story with pliers and other tools began.