Opinions on this motor. 1980-83 40hp

[Wildlifedesigner]

The engine on my boat is a 80 - 83 40hp merc. Serial # 5992846 Thunderbolt ignition. This is not the 402. It now has water coming out of the water jacket around the spark plug, so I am considering rebuilding it. Although I dont have very much experience, This motor also feels like it is a little underpowered for a 40 hp, and I have been told that this moter is a real "dog". Basically I would like to know if this motor is worth rebuilding to gain some more power.? The compression on both cylinders is 120 The top speed on my 16 foot deep V tracker trimmed out with the CMC is about 25 max @5000 rpms the hustler prop is a 10 3/4 x 12

 

[andrewkafp]

Re: Opinions on this motor. 1980-83 40hp

25 Knots out of a 40hp on a boat that size is not bad. The problem is that 40hp is a bit underpowered for the boat size. I reckon you need around 60-80hp. 120 psi is about right. The water jacket leak can be fixed with JB Weld or removal of cover and new gasket, which will involve the breakage of bolts and subsequent drilling out of the old ones and re-tapping new ones. My 2c..Patch up the water jacket and keep running until it needs a re-build.

 

[Wildlifedesigner]

Re: Opinions on this motor. 1980-83 40hp

I did fail to mention: in the last outing while running at 3000 rpms (full throttle, would not go up in rpms possibly due to water conditions or load?) there were some clunk noises which appeared to be coming from inside the motor, which led to the motor dying, and not starting. Could it have overheated, or can the water get inside of the cylinders?. Now that I am at home the motor starts and runs fine, but sometimes takes a little time to start. Also The water coming out from around the spark plug kind of squirts out.

 

[andrewkafp]

Re: Opinions on this motor. 1980-83 40hp

The water from around the plug will not get in the cylinder.I have successfully fixed this type of problem on my 1980 Merc I used to own. I will attach a link when I find it. Don't know abiut the "Clunks" , but if it still runs and pee's it sounds OK. Give it plenty of choke when cold and none when warm.<br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=29;t=015043#000008