1975 Merc 115 water coming from arouns spark plug????

[Bob37814]

I have a 75 115 inline, 120 on all 6 cylinders, starts up and runs good, but gets hot after about 1 minute. It is pumping water out the peehole, but I can also see water coming out from around plug#1. After investigation on another old blown inline block I have in my junkpile, I noticed the gasket on my good inline seems kinda frayed or cracked if you will. My first thought was water getting into the combustion chamber, but removing the plugs and cranking, there was no water or mist coming out, and the plug itsself wasnt clean, which leads me to believe maybe the rear water jacket gasket is bad. What id like to know is if these gaskets are sold in singles, and does it sound like I am on the right path. Thanks a bunch

 

[Laddies]

Re: 1975 Merc 115 water coming from arouns spark plug????

No water is getting in the cyl from that leak it's the cyl block cover gasket thats leaking, if you decide to replace it get some penatrating oil on the bolts a few days before and use care in removing them. They break easily.

 

[Moody Blue]

Re: 1975 Merc 115 water coming from arouns spark plug????

The water seepage from around the #1 plug won't affect cooling much if at all.

When you say "gets hot after about a minute" what do you mean? Do you have a temp gauge or just by feel?

When was the last time the water pump impeller was changed? Even though it is moving water, it may not be doing so effectively or you may have a blockage somewhere in the cooling system. Sometimes old impellers come apart and the pieces travel through the system until they encounter a small passage where they become stuck and restrict the flow of water.

 

[Bob37814]

Re: 1975 Merc 115 water coming from arouns spark plug????

Well, the motor was actually bought yesterday. Guy said he changed it 6 months ago before the transom went bad on the boat in which it was rigged, but sat in a heated garage until I acquired it. For a mere $200 bucks, I ran compression test which was 120-125 down all 6, and hot blue spark as well. It pumps water, but it takes about 10 seconds(running in a large plastic tote filled with water) But when it begins to pee, the stream is so blasted hot that it steams when exiting. The water around 1 and 3 sparkplugs dosent bother me as bad as the excessive engine temperature. but now I guess I drop the lower unit and begin the investigation

 

[Yepblaze]

Re: 1975 Merc 115 water coming from arouns spark plug????

I'd scratch, and blow out all the loose crud around the effected area before pulling plug.

Then I'd degrease the area, grab a new plug, put a 1/8", or so bead of silicone around the gasket area, screw it in, and let it dry. It will usually squish out to the leaky area plugging off the leak.


It's a lot easier running, (and looking at) a neatly applied patch then staring at a bunch of broken off bolts.

 

[Bob37814]

Re: 1975 Merc 115 water coming from arouns spark plug????

Blaze, I thought about that, just using a couple tubes of black permatex, cleaning it all up, and taking my time and reseal every nook and cranny where the gasket lines are. As for the impeller, Guy didnt lie, all 6 fingers went straight after I pulled it from the housing. There was a few flat slivvers of rubber stuck in the water tube in the housing. AND the water tube going into the powerhead id krinkled up a little bit, but is free of obstruction. Should I blow compressed air into the water tube to see if any comes out the pee hole?