1996 johnson 70 hp two stroke j70tleda milky sludge on number 3 spark plug

TBTech24

Seaman
Joined
May 3, 2011
Messages
56
motor impeller failed overheated. retrieved all the pieces to the impeller replaced water pump, visually inspected wires and hoses. and of course spark and compression. everything looks good, fired up the motor on the water hose ran well and sounded good. took the boat to the river for a sea trial and was hard to start at first then idled fine. went to increase rpms to take off and immediately she fell flat on her face and died. hard to start again. finally got it running and idled around for a min then tried to take off and she died again. even harder to start. till both batteries where dead. i paddled back in for an hr and when i got back to the house i pulled the plugs and rechecked compression before i dove into the carbs. compression was great. spark plugs not so much. number three had milky sludge on the tip. the cylinder walls and piston looked ok., cleaned the plug and dried out the cylinders. also pulled the intake silencer and noticed the little hose on the bottom coming from the bottom of the crankcase was full of the same milky sludge. in the bottom of the cover as well. fired it back up on the hose and ran it for a while and ran ok. shut it off let it sit for about 15-20 mins and pulled the plugs. same cylinder milky sludge along the elctrode and around the porcylin. Anybody have any ideas?
 

Daviet

Fleet Admiral
Joined
Sep 24, 2008
Messages
8,958
Re: 1996 johnson 70 hp two stroke j70tleda milky sludge on number 3 spark plug

Sounds like you might be getting some water into the cylinder. You might think about pulling the head and looking at the head gasket and see if it is leaking into the cylinder. You could also have a problem with the exhaust cover gasket leaking.
 

TBTech24

Seaman
Joined
May 3, 2011
Messages
56
Re: 1996 johnson 70 hp two stroke j70tleda milky sludge on number 3 spark plug

thats what i thought. water in the cylinder. i was also thinking fuel oil mixture but thats probably cuz the cylinder isnt firing. Thaks for the advice. looks like im going exploring.
 
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