1955 Evinrude 25hp Aquasonic lower gearcase seal problems

[TimCA]

Hello everyone. I've recently acquired a 1955 Evinrude 25hp Aquasonic Electric start (given to me). At first inspection everything seems clean, turns over with descent compression, shifts, things move correctly, the spark plugs look good, starter might be a bit bad. No cracks on the housing, block, or shaft. I know there have been problems with the lower gearcase seal. My serial number is 11348, model 25920 and it appears to be after the ingenious engineering change. I'm ready to tear it down. Before I acquire the manuals, replacement parts and overhaul the motor, I was wondering if anyone new the specifics on the lower gearcase problem. How do I detect if the problem was fixed or replaced? What damage would be detected? How would I go about with a remedy? I'm fairly mechanically inclined, can fix just about anything, but want to know what I might have on hand here. I appreciate any comments, I'm learning a lot here and I thank everyone for their help.

 

[RCO]

It is the lower crankshaft seal that is the problem with those, not a gearcase seal. You would need to completely disassemble the powerhead and change out the lower main bearing to be able to use the regular carbon seal used on the big twin before and after the mid-late 1955 mistake. When they failed the seal would let water into the crankcase and rust the bearings, rings, etc. Look for any signs of rust on the bearings. Any rust at all on the bearings is cause for replacement.

 

[TimCA]

Wow, thanks RCO. I'll look at that first and see what I'm into and how bad it is or if the previous owner remedied the problem. Everything turns easily without the plugs in and looks like it was recently ran (within the last 5 or so yrs). The previous owner did have several other vintage motors, so the upkeep might not be so bad. Let me know of any further info on this. I plan on taking pics and posting as I go so others may learn as well as myself.

 

[thatone123]

WOW, what a name Aquasonic...Those were the days my friend. Todays might be called Complasonic...like complicated.