Water Jacket Cracked? 1978 Merc 900

[nate_evans79]

Hello,
I have a 1978 Merc 900 (90 hp inline 6), on a 17' Monarch McFast bass boat. I have it up for sale, and was doing some maint. checks on it last night, cause someone was coming to look at it. I noticed that while running it on the earmuffs, that the telltale stream wasn't very strong. I at first figured that because it sat for about 8 months, that the impeller was just in need of changing, or that the tube had been clogged by ants or something. So i pulled the cover off, pulled the tube off, and cleaned it out. left the cover off, and started it back up on the muffs again. While looking at the motor from the rear, the left "water jacket" (not sure if thats what its called) was gushing water out of a 1"-2" crack near the second to bottom bolt on the cover over there. I shut it down right away. the motor was not knocking or making any noise that would indicate any internal damage.

1-what could have caused this, and
2-what can i do to fix it? can it be welded back up? or just the cover be replaced?

Thanks.
Nate.

 

[Laddies]

Re: Water Jacket Cracked? 1978 Merc 900

The leak should not hurt he engine but should be repaired ASAP Either method you mentioned should work, your choice.

 

[nate_evans79]

Re: Water Jacket Cracked? 1978 Merc 900

would something like jb weld hold in that location?

 

[Chris1956]

Re: Water Jacket Cracked? 1978 Merc 900

Nate, Epoxy putty or even silicone may repair that leak. The pressure is only a few PSI.

 

[nate_evans79]

Re: Water Jacket Cracked? 1978 Merc 900

awesome, thanks. thats what i was hoping to hear. I really didn't want to have to tear it down to far.

I've already rewired the entire boat, new harnesses inside and out on the motor, and rebuilt the carbs, new starter, new stator, fuel pump, water pump, and just about everything else on the boat. I thought i was about done. haha, done working on a boat, thats a good one. haha.

Nate.