Reply To: Grease Gun Method

[Sam M.]

Yes the grease gun method does work.  I have a motor where the grease gun method was used by a previous owner, and it worked until the grease started to escape from the ports.  It might be possible to seal off the ports with sheet metal and gaskets and keep going, but in my case, the pistons were pushed over rusty areas of the cylinder wall, which is not helping me unseize the pistons.  Nonetheless, I would definitely recommend the grease gun method once the cylinder walls are rust/corrosion-free.

Some advantages to the grease gun method include:

• It gives uniform pressure on the top of the piston.  The grease is pushing everywhere, unlike hammering a wooden dowel on the piston, which would only put pressure on the middle.  –   Side note, if possible, avoid hammering on the piston unless it’s a last resort because if the piston doesn’t want to move, the hammer’s force (use wood in between hammer and motor) may push the metal of the piston outwards (towards the cylinder wall, as the metal has to go somewhere) if the piston won’t move downwards, thereby widening the piston and making it harder to take out.  However if the piston can move and is just tightly in there, gentle taps with a rubber mallet alongside penetrating oil should be ok.
• Grease does not dissolve metal.  Trying various mixes of fluids risks the possibility of some metal getting dissolved on a small scale, which could reduce compression.  Think vinegar, for example.  Eventually as it’s acidic, it will consume small metal shavings.
• No heat is needed so there’s no risk of deforming any parts or affecting the factory’s heat treatment to the metal.  Sadly, I have personally witnessed a seized old outboard part become unuseably warped due to overheating and applying pressure while the part was hot.
• You are forcing a lubricant into the system.  That’s helpful when dealing with a seized part😄