1972 85hp evenrude overheats

[edylc69]

I'm stumped. My motor overheats after running at full throttle for 2-3 min. I can run at slow speed all day with no problem. The water pump and thermostat are new. Hot water does come out of the lower unit after the engine has warmed up. I would love to be able to fix this if it is simple enough.

 

[pennyanman]

Re: 1972 85hp evenrude overheats

Pull the heads. The water deflectors are swolen and are blocking cooling water from getting around the cylinders correctly. Full throttle overheat was how I found out about them. Get a shop manual and follow the directions. The job is easy and a good maintenance practice every few years. Make SURE you use new gaskets.

 

[Walker]

Re: 1972 85hp evenrude overheats

Could also be caused by scale build-up inside your water passages. Do you run it in a electric plant cooling lake. I see this problem quite often on motors run a lot in the two cooling lakes around san antonio. And carbon buildup on the piston heads, cylinder heads, and exhaust ports can also cause overheating.

 

[edylc69]

Re: 1972 85hp evenrude overheats

Thank you Captain Walker. I finally got around to pulling the heads and sure enough the intake hole was clogged with a little bit of grass. Thanks again now I can look forward to the upcomming season on the bay.