1993 Evinrude 90hp V4 overheat

[jkgroff]

My motor overheats only when run wide open. I've replaced water pump, thermostats, flow restrictors. Still overheats but only when run wide open. I talked to a mechanic who thinks the problem is electrical, not water flow. He said the timer might need replaced.

Thanks for any thoughts
Mojogroff
Daytona Beach

 

[Walker]

Re: 1993 Evinrude 90hp V4 overheat

I'm thinking you might have corrosion buildup in the water passages. That would insulate the block and not allow the cooling water to absorb enough heat as it circulates. WOT is where the motor is creating the most heat. Try some kind of flush. My personal favorite is a barrel with 10 gallons of pickling vinegar and water up to the water pump level. Run the motor til it reaxches operating temp then shut it down and let sit til it cools. Repeat the process as many times as you can in 3 days. That should clean the passageway pretty good.

 

[jkgroff]

Re: 1993 Evinrude 90hp V4 overheat

I'm thinking you might have corrosion buildup in the water passages. That would insulate the block and not allow the cooling water to absorb enough heat as it circulates. WOT is where the motor is creating the most heat. Try some kind of flush. My personal favorite is a barrel with 10 gallons of pickling vinegar and water up to the water pump level. Run the motor til it reaxches operating temp then shut it down and let sit til it cools. Repeat the process as many times as you can in 3 days. That should clean the passageway pretty good.

 

[jkgroff]

Re: 1993 Evinrude 90hp V4 overheat

Walker thanks for the suggestion, when I replaced the flow restrictors there did not appear to be a lot of corrosion or build up inside the head. But maybe I'll try the vinegar deal. Where do you get ten gallons of pickling vinegar?