Water Leak in 20 hp Merc

[TarHeel]

While rewiring my 20hp merc, I accidently broke off the corner of the plate covering the left side (from behind) of the motor. The break occured near the top lefy bolt that attaches the cover to the block. When I started the motor, water leaked from the crack so I got another cover from a spare motor, gaskets and put it all together. Then it leaked water from the top left bolt so I cocered it with marine tech and let it dry. OK now it doesn't leak but the engine ran really rough for about an hour then settled down and ran fine. It was pumping water OK too.<br /><br />Is it possible that I got water into the cylinders on the other side of the water jacket? I also put new gaskets in the carb so its possible, I guess, that I got a small piece of trash in the jets while I had it apart. I'm not one to mess with the engine while its running fine but I can't figure out why water would leak out of a perfectly good bolt. Any ideas?<br /><br />Thanks.

 

[12Footer]

Re: Water Leak in 20 hp Merc

That plate is the exaust port plate,and has both a dry area and a part of the water jacket. It is possable to get an internal leak,allowing water to get into the normally dry chambers. Remove the plugs, and examine them.If one looks cleaner than it should, there is a chance the exaust port plate is leaking. The engine will run rough due to water fouling the plug. This plate requires a sequence of tightning,just like the head would.

 

[TarHeel]

Re: Water Leak in 20 hp Merc

Thanks 12Footer for the information. I'm reluctant to mess with it anymore since it seems to run fine now but just in case I have to go back in there, do you happen to know the tightening sequence and the torque pressure? I tightened without torquing but they are pretty tight. Any more pressure and I thought I would snap the bolt heads off.<br /><br />I wish I had a repair manual for this motor.