Step-By-Step Instructions: Safely Removing Pistons From Bottom of Engine Like a Pro!

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removing pistons from bottom of engine

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The primary job of pistons is to convert the energy released in the combustion chamber into mechanical action. However, like other engine components, pistons usually wear out over time, requiring a replacement.

So then, what is the process of removing pistons from bottom of engine and replace? Technically, the process varies according to your vehicle model. For some vehicles, you only detach the connecting rods from the crankshaft. Then, slide out the pistons from the rods by removing the piston pin. However, some vehicles require that you remove the crankshaft too.

But why pull out the pistons from the bottom of the engine and not from the top? Read our guide to find out this and much more.

removing pistons from bottom of engine

Can You Remove the Pistons from the Bottom of the Engine?

Yes, it is possible. The process involves removing the crankshaft and the connecting rods out of the way. Then, remove the pistons from the engine block by pulling them out from the top.

Unfortunately, it can be hard to install the pistons back in a similar way without removing the engine cover. And hence, the benefits of removing the engine cover come.

However, with some automotive engines, removing the pistons from the bottom of the block is impossible. This is because the primary bearing journal is usually in the way of the bottom of the bore.

But if your car has a monobloc engine, you can remove the piston from the bottom. A monobloc engine is one whose key components, including the crankcase and cylinder head, are cast as a single unit. As such, all the cylinders share a standard block.

Why Remove Pistons from the Bottom of the Engine?

If removing the pistons from the top of the engine, the process is quite lengthy.

  • This is because there are many components you must remove to access the pistons.
  • For example, you must unfasten the timing belt, intake and exhaust manifolds, cylinder head, and all vacuum lines.
  • You also have to drain the oil and uninstall the oil pan.
  • Apart from that, you must disconnect the piston rod caps one at a time. As such, this is a job best left to a professional mechanic.

Conversely, when removing the pistons from the bottom, there are a few parts to pull out. These include the crankshaft, connecting rods, and piston rod caps. And in some vehicles, you can disassemble the pistons without removing the crankshaft.

How To Remove Pistons From the Bottom of the Engine? (6 Easy Steps)

Generally, it should be easier to extract the pistons from the bottom of the block with the crank out of the way. Here are step-by-step instructions on how to do it.

Step 1: Park your Car

  • Park your vehicle on a flat surface and turn off the engine. If on an uneven surface, you can break the piston rings.
  • Now, you can raise the car using hydraulic jacks to get better ground clearance.

Step 2: Rotate the Camshaft Sprocket

Use a socket wrench to rotate the camshaft sprocket for a couple of turns. This will help move the pistons down at the bottom of the board. The sprocket is attached to the camshaft’s one end, located at the top of the engine.

Step 3: Unscrew the Bolts

  • Next, get underneath your car.
  • Then, locate bolts securing the pistons to the bearing caps on the crankshaft. They are about 4 to 8, depending on the number of cylinders your engine has. And based on the number of cylinders your vehicle has, you may have to remove 4 to 8 pistons.
  • After that, get a 5/16-inch socket and ratchet and unfasten all the rod cap bolts.
  • Then, remove the big end of the bearing cap to disconnect the connecting rod from the crankshaft.

Step 4: Slide Out the Pistons

  • Now, slide out the connecting rod assembly and the piston out of the cylinder bore from the bottom of the engine. Typically, each piston is attached to its own connected rod.
  • So, once you have removed one piston, you must repeat the process for each connecting rod assembly and piston. However, I suggest you be careful to prevent the connecting rod from scratching the crank journals.

Step 5: Take Out the Crank

  • If you cannot remove the pistons because the engine’s crankshaft is in the way, simply remove the component. But first, you have to drain the oil.
  • Then, uninstall the oil pan to expose the crankshaft.
  • After that, take out the connecting rod caps that affix to the crankshaft. If your engine has 6 cylinders, you must remove six caps to separate the connecting rods.
  • Then, unfasten the 4 main caps that secure the crank to the engine block. This will release the crankshaft. But while removing the last cap, be careful so the crank does not fall on you as it’s heavy.
  • With the crank out, you just need to detach the connecting rods from it to remove the pistons.

Step 6: Detach the Pistons

  • Once you have detached the connecting rod from the crankshaft, you can pull out the pistons. Simply remove the piston pin, which is a link between the connecting rod and the piston.
  • To remove the piston pin, get needle nose pliers. Then, carefully twist and pull the spring clip out of the piston.
  • Next, slide out the pistons. Alternatively, you could use a universal piston pin puller. In this case, I suggest the NACHMAN designed to remove all sizes of pins without damaging the piston.

Tips for Removing Pistons From Bottom of Engine

Removing pistons from the bottom of the engine can be challenging if you don’t know what to expect. So, here are tips to help you with the process.

  • Be sure to mark the direction of each piston and label what cylinder they came out of. This is because each piston wears slightly differently in each cylinder.
  • If the pistons are stuck on the connecting rod, tap them out using a wooden dowel or hammer. Do it gently.
  • Consult your vehicle’s service manual so you know what engine type your car has and even the number of pistons.
  • Keep all small parts, such as the bolts, in a storage bag to prevent them from getting lost.
  • You should not remove the piston compression rings since they are fragile and will easily break.
  • When reinstalling the pistons, be sure to install the crankshaft correctly. If you don’t, you can get engine codes p0016 and p0017, a sign the crankshaft and camshaft positions are misaligned.

Final Remarks

Technically, removing pistons from bottom of engine is much easier than from the top. However, this is only possible with some engine types, especially the monobloc style. The benefit of pulling out the pistons from the bottom is that you don’t need to remove the cylinder head.

You also don’t have to remove engine components, such as the intake and exhaust manifolds or vacuum lines. Removing the pistons involves separating the connecting rods from the crankshaft. That said, for ease of removing and reassembling the pistons, there are several tips to help you.

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