Drowned 25 Merc

goblerblaster

Petty Officer 2nd Class
Joined
Dec 26, 2011
Messages
176
Drowned Merc 25 won't start

I lost my 1987 , 25 HP merc overboard into a freshwater lake. It was on the bottom for a week before recovered and immediately did the recommended dry out procedure. The motor was running about 1/2 throttle when it went in. I have cleaned the carb, dried out the electrical connections, put alcohol in the cylinders- and of course oil. Now , when I pull the starter rope, I get a "pow" like a backfire on the first or second pull. Exhaust smoke come out, but it really doesn't sound like it is trying to start. Then, I can pull it 50 more times and nothing happens. I can wait a day and try to start it again- and "pow" on first or second pull and then nothing until the next day? Compression seems to be good., but I have not had a gauge on it.

Any suggestions on what to try next?
 

goblerblaster

Petty Officer 2nd Class
Joined
Dec 26, 2011
Messages
176
I lost my 1987, 25 Merc into a freshwater lake. After 7 days it was recovered. It was running about half throttle when it went in. I followed the recommended " dry out" procedure. Now when I try to start it, it will "POW" on the first or second pull and exhaust smoke will come out of the prop hub. Sounds like a backfire. I can pull it 50 more times and it won't do anything. The next day I can try it again and "POW" on the first or second pull and then nothing for 50 pulls or until I give out from pulling the starter rope ?? Compression seems to be as normal.

Any suggestions to get this going? It was running perfect when it went in. THanks
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
36,047
It is very critical to get it running ASAP------Most folks do not understand how quickly things can corrode in fresh air.--Check flywheel key-----Try switching the plug wires.
 
Last edited:

wired247

Lieutenant Commander
Joined
Oct 8, 2011
Messages
1,557
Personally I'd be tearing it apart for a rebuild or at least a thorough inspection and probable reed change and I'd be testing/changing the electrical components that do doubt went to hell. Remember water does not compress well or at all and theres probably more to do than you realize.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,036
Sometimes when a running motor hits the water, the resulting hydrolocking can bend connecting rods. So, with the spark plugs out, does it turn over very smoothly by hand? Obviously the next step is to check the firing of the spark plugs, followed by the supply of clean, pure fuel. You have cleaned out the carbs?
 

goblerblaster

Petty Officer 2nd Class
Joined
Dec 26, 2011
Messages
176
Yes, I cleaned the carbs and the motor turns smoothly with the plugs out or in. It has good spark. I have not checked the reed valves, but will try that next. The magnets on the flywheel or in the proper position. It may be a parts motor if I can't get it to go soon........
 
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