Car engine repair often involves piston installation. While the process might look simple, doing it wrongly could cause the engine to malfunction. It could even result in severe piston damage shortly after (and another repair process). If looking to rebuild your engine, read to the end. We compiled piston installation directions, presenting them in a way that is easy to understand.
The piston installation procedure described here covers the following: the preparations to make, precautions to observe, and the steps to follow. We are assuming that you have the engine already disassembled, which is another process itself.
Before you can even begin, ensure you have the right piston. Do that by measuring both the piston and the cylinder it will go into. The piston cylinder clearance should be within what the engine manufacturer recommends. The clearance of the piston rings too.
Piston Installation Materials and Tools
You will need:
- Some protective gear such as goggles and gloves
- A piston install tool called a ring compressor to place the piston in the cylinder
- A piston ring expander tool or pliers to remove or install piston rings
- Assembly oil to lubricate the piston parts
- Towels (lint-free) to clean the cylinder
- Dead blow hammer or what some people call a piston hammer
- Piston kit ( if you are not reinstalling the old piston)
The Piston Installation Process
Here is how to install a piston or pistons.
Step 1 Clean the Cylinder Bore
Using the towels, wipe the cylinder bore until the towels come out of the cylinder clean. If you are reinstalling the pistons, wipe the also. You want to get rid of dirt and other particles that could cause cylinder and piston damage by wearing out the surfaces.
Step 2 Oil the Piston and Piston Ring Compressor
Oil piston parts such as ring grooves and wrist pin, applying a generous amount of the lube. Lubricate, also, the ring compressor with a moderate amount of oil.
Step 3 Install the Piston Rings
With the help of the piston ring expander tool or piston ring pliers, install the compression rings. The tool expands the rings to increase their diameter so you can easily slip them on the piston. You can also use the tool to remove the rings. Spread lube around the rings.
Step 4 Install the Piston Ring Compressor
Place the ring compressor on the piston. It is just a matter of loosening the tool to increase its diameter so it fits the piston. Once the piston has gone into the compressor, tighten it until it presses the rings and makes a firm hold.
Step 5 Oil the Cylinder Bore
Spread oil on the wall of the cylinder that will receive the piston. This will help to make the piston installation safe and easy. But most importantly, the lube prevents the initial piston stroke from happening on a dry piston and cylinder
Step 6 Insert the Connecting Rod Bearing
Install the piston bearing that is located on the big side of the piston rod. Lubricate it just like you did the other parts of the piston assembly.
Step 7 Place the Piston in the Cylinder
With the ring compressor tool still holding the piston, place the assembly on the cylinder block, ensuring the compressor fits the top diameter of the cylinder. Then, use a dead blow hammer or the wooden part of a regular hammer to tap the piston gently. The aim is to drive it into the cylinder. Ensure the piston does not go too far down, or the connecting rod will scratch the vilebrequin.
Step 8 Remove the Piston Ring Compressor
If the compressor was installed correctly, the piston should fit into the cylinder bore together with the rings. You can now loosen the compressor and push the piston further.
Step 8 Connect the Crank Shaft
Turn over the engine over to access the crankshaft. Use one end to rotate the crankshaft while the other guides the piston rod towards the crankshaft journals. Once in position, insert the lubed bearing and the connecting rod caps. Install the conrod end cap bolts.
Step 9 Torque the Connecting Rod Bolts
Tighten the piston rod bolts using the manufacturer’s specifications for torque. If the engine had other pistons to install, follow the same procedure. Ensure every part is running correctly. The piston installation process is now complete.
Piston Installation Tips
While the piston installation process described here may appear simple, it chances of making a mistake are many. Pistons are sensitive engine parts, and one wrong step could cause problems. To ensure everything goes as expected, follow these rules.
- Always measure the cylinder bore and piston sizes before going ahead with the installation. Incorrect dimensions can result in piston seizure or excessive clearance. Improper piston fit could cause a loss of compression, gas and oil leaks, and more.
- Sometimes, the cylinder bore is scratched and scuffed and needing to be bored. Ensure you understand what it means and the requirements for the piston size.
- Have with you the right piston installation tool. In this case, the tool to use is the piston ring compressor. There is also the ring expanded or pliers. For piston measurement, use a micrometer and set of feeler gauges.
- Avoid forcing the piston down the cylinder bore. In most cases, it will be possible to push it with just the hand. If it proves hard, use a head blow hammer. Tap on the piston crown gently to avoid damaging parts such as piston cap, crown, skirt, and others.
- Lubricate both the piston and cylinder walls adequately, especially the parts that experience movement such as wrist pin. The ring compressor also needs to be lubed to allow the piston slide into the cylinder easily during installation.
Piston installation can be done in simple steps, but only if you know how to do it right. Also, if you have the right tools and materials. While the procedure itself is important, the preparations you need to make are even more crucial. These involve sizing the piston and the cylinder bore. For that, check our piston measurement article. It explains the process to obtain the dimensions for clearance, size, and other aspects.