I really need some direction for overheating

[wlbolerdo]

Once again, I have a '92 70 hp evinrude. Bought the boat in April '07, it did not have a theromstat in it. From April 'til July the motor went down hill. I pulled it apart and found pistons and cylinder walls trashed. I have since rebuilt the powerhead, soaked and rebuilt the carbs, installed new reed valves and a thermostat and replaced the water pump. Took it out Sunday and at idle the temp. is 160 degrees. It got up on plane real quick but the temp went to 220. I have run the boat without the thermostat and it ran fine. This is the first time I've run it with a thermostat.
I'm starting to think that I'm getting closer to finding the reason why this motor was on it's way out when I bought it.
So some direction would be very cool.
Thanks,
Wayne

 

[lyncraft_mechanic]

Re: I really need some direction for overheating

well if your engine is getting that hot i would suspect to see some form of steam associated with that kinda of tempature(220), maybe your in dash gauge is faulty, try buying or borrowing a infrared thermometer they are alot more accurate. have you tested your new thermostat, just because the thermostat is new doesn't mean that it is working properly.

 

[wlbolerdo]

Re: I really need some direction for overheating

I couldn't keep my hand on the flywheel for more than maybe 5 seconds. Can I drop the t-stat into boiling water to check it?

 

[lyncraft_mechanic]

Re: I really need some direction for overheating

yes attach your thermostat to a peice of wire and place in some boiling water and if it's good it should open

 

[wlbolerdo]

Re: I really need some direction for overheating

I have it in hand now and will check it now.

 

[wlbolerdo]

Re: I really need some direction for overheating

T-stat is opening and closing. I'm going to relocate the telltale from the exhaust housing to the top as seen in service bulletins. I really don't believe this will solve my problem. It may only eliminate a reason for the overheating.

 

[Benny1963]

Re: I really need some direction for overheating

is the therm new. are the deflectors in powerhead .poppett valve good ,
i would shoot it with gun and go back thru cooling system,
good luck .i dont have a lot of ex with the three cyls, i have a couple of v6s and work on and old merc or to,some one will come along