Question: I need to change the Piston in my VMAX ABC type engine. How do I remove the Piston without damaging anything?

Answer: First of all you need to remove the cylinder (sleeve). Please see the How to Remove the Cylinder (Sleeve) procedure below.

Note that in nearly 100% of cases, when replacing the piston in an ABC engine, the cylinder should be replaced also. They are generally sold as a set.

Once the cylinder has been removed you can remove the piston complete with connecting rod and wrist pin. There is a trick to this. Please put away your hammer, vice grips, pliers and cutting torch and obtain a carriage bolt that is about 3/16" in diameter and about 3" long. Carriage bolts have a rounded dome like head and are available in pretty much any hardware store.

Securely tighten the prop nut and prop which will serve to pull the crankshaft as far forward in the crankcase as possible. Remove the crankcase backing plate. Lubricate the bottom of the connecting rod where it attaches to the crankshaft pin. Use Pacer After Run Oil or other lubricant. Remembering that there is no cylinder in the crankcase, carefully and slowly rotate the engine 2-3 times by hand and stop with the piston at top dead center (highest point) in the crankcase.

Carefully insert the head end of your carriage bolt into the bottom of the crankcase so that the domed head is centered on the back of the crankshaft and the edge of the domed head is under the bottom edge of the connecting rod. Now use the carriage bolt like a pry bar, to pull the connecting rod back and off the crankshaft pin. There may be some resistance just as it is about to come off. Apply a bit more lubricant and using a bit more pressure on the carriage bolt, rotate the prop about 10-15 degrees and the connecting rod will come off the crankshaft pin.

Flush out any small filings of brass or aluminum using Pacer Degreaser. These small pieces won't be missed by the connecting rod but you don't want them getting into the engine or bearings later on.

Question: I need to change the cylinder on my VMAX ABC type engine. How do I remove the Cylinder without damaging anything?

Answer: Install a propeller and tighten it securely. Remove the glow plug and brass glow plug washer. Remove the head. Rotate the propeller until the piston is at the bottom of the large exhaust port. Position the brass glow plug washer on top of the piston so that about 10-15% of  the brass glow washer protrudes into the exhaust port but not beyond the outside diameter of the cylinder. Hold the engine level and rotate the prop so as to raise the piston. The brass glow plug washer will catch on the side of the exhaust port and you can then use the leverage of the propeller to literally lift the cylinder out of the crankcase.

Note that in nearly 100% of cases, when replacing the cylinder in an ABC engine, the piston should be replaced also. They are generally sold as a set.

Better Answer: The trick to this is NOT to use vice grips, pliers or other tools on the cylinder itself. Follow the procedure outlined in the Answer above. The brass washer is softer than the plated cylinder and the piston so that it will not mark either when used as a lifting wedge. The propeller provides plenty of convenient leverage to literally lift the cylinder right out of the crankcase.

If the cylinder will not move using this technique try the following: Install the engine in a test stand or clamp GENTLY in a vice (emphasis on GENTLY!). Keep uplifting pressure on the brass washer and cylinder via the propellor. Heat the crankcase top section around the cylinder with a heat gun. This will expand the crankcase somewhat allowing the cylinder to move more easily. Increase the pressure on the prop and the cylinder will move upwards and out of the crankcase.

If the cylinder will still not move after heating the crankcase try the following next: Leave the engine clamped down. Get a can of Pacer Degreaser. Use eye protection and rubber gloves. Move outside. We are not going to use the Degreaser as degreaser per se. It has another quality that we need. It has a very high evaporation rate and cools whatever it is sprayed on. So we are going to use it to cool the cylinder liner after heating the crankcase. The heat will expand the crankcase and the degreaser cooling will contract the cylinder allowing the cylinder to be removed from the crankcase. It is important to DO THIS OUTSIDE. Do NOT USE your heat gun and your degreaser at the same time. Keep uplifing pressure on the brass washer and cylinder via the propellor. Heat the crankcase top section around the cylinder with a heat gun. Don't go overboard. Just get it nice and warm. TURN OFF THE HEAT GUN and set it aside at a safe distance. Now take the degreaser and spray a good blast into the cylinder on top of the piston. This will cool the cylinder quickly. Now increase the pressure on the prop and the cooler contracted cylinder will move upwards and out of the heated expanded crankcase.