1973 Mercury 115... RIP or ? Bad Compression? etc

[snwwlkr]

Recently bought a Glastron Carlson cvx-16 project boat. Bought it just for the boat ($250.00) but it included a 1973 Mercury 115hp motor, if the motor was savable that would have been just a bonus. History of the motor is ZERO. Motor looks fairly clean and un-molested. Truth is the wiring is disintegrated inside of the motor and must be almost totally replaced. Me nor the previous owner have ever seen the motor run, he bought it as a project and never started it. Judging by the shape of the bought its been 5 yrs minimum since its run. I have no idea if the lower unit works properly. I checked the compression and this is my REAL problem... 145-150 on all cylinders except #3 which is 125. I'm thinking from all I know and all I've read this is NOT good? Sprayed light oil into the cylinders and it made no difference in the psi on #3. If I knew it shifted good and all else was basically good I could deal with the wiring and even maybe the psi issue on #3 but all things considered I'm just not feeling the love here.

Sounds like time to sell for parts or part her out unless someone here has something REALLY hopeful to say......

 

[444]

Re: 1973 Mercury 115... RIP in ?

Re: 1973 Mercury 115... RIP in ?

One lower cylinder isn't great, but 125 is still enough for it to light the fire and run well.

 

[Chris1956]

Re: 1973 Mercury 115... RIP in ?

Re: 1973 Mercury 115... RIP in ?

Your compression is fine. Drain and refill the gear oil. Hopefully the old gear oil is clean.

You need to do a spark test to make sure the trigger and switchbox are good. How are the wires from the switchbox to the distributor? If the conductor is intact on them and and you can insulate with shrink tube and electrical tape, you can run the spark test. Post back and I will tell you how.

 

[snwwlkr]

Re: 1973 Mercury 115... RIP or ? Bad Compression? etc

Well thats all good news. I thought my psi was out of the acceptable range. I will proceed forward with the rewiring and spark check. Wires from the switch box to the distributor are some of the few that look decent.

Anyone have the wiring diagram for this motor?

 

[Chris1956]

Re: 1973 Mercury 115... RIP or ? Bad Compression? etc

Sure, look on maxrules.com for the wiring diaghram.