Water leak Lower unit

[maxxxair]

Hi all. Johnson 70 1978....On the lake motor started bogging down and smoking white smoke. I noticed water coming out of the two upper exhaust ports (top of lower unit) and the water was hot. When I got the motor it had a bad head gasket which I replaced and motors been fine for 3 yrs. Thought maybe gasket was bad again so replaced it. Hooked the cups up and motor ran awesome. Took the boat to the lake and white smoke and barely running. Trimmed the motor up till just the main water intakes were submerged only and motor runs strong but as soon as I submerged the lower unit it bogs down. Theres alot of water coming out where the L Unit connects to the motor. Any ideas anyone? Easy to fix or omg?

 

[mikesea]

Re: Water leak Lower unit

start by doing a compression test,you may have blown the gasket again,the smoke ,if steam indicates overheat = head gasket,have you changed impeller latly,you may not be getting the water volume u need for cooling,or thermostat could be stuck,you can remove it a see if the problem goes away,but do comp first

 

[tashasdaddy]

Re: Water leak Lower unit

just because you have a pee stream, does not mean the tstat is opening an cooling the motor. i agree with Mike.

 

[maxxxair]

Re: Water leak Lower unit

gonna do the comp test this weekend but can someone explain why it runs perfect with the cups on but not in the water? If it was a head gasket wouldn't the water from the cups get in the motor?/?......CONFUSED

 

[mikesea]

Re: Water leak Lower unit

Its more the loss of compression,with no load,the eng.can appear to have no problem.But you may have 1 or more cylinders no operating to spec.Another thing,it may get water ONLY after the eng has heated up and heat allows a void for water to pass.Expansion and contration of metals can do BAD things