Evinrude 28hp overheating

[Trakker]

Have a 1988 Evinrude 28hp that’s overheating. Replaced water pump and housing. Starts up and water is coming out exhaust and telltail, but eradicate. Telltail seems to pulsate, not even stream. Them seems to stop at telltail and start to steam. Removed thermostat and still does same thing. Checked compression 125lbs each cylinder. Wondering if head gasket could have slight hole into water jacket. Doesn’t seem to run very smooth and spits every so often

 

[racerone]

A common mistake when testing in a bucket is not enough water.----Water must be 6 or 8" above the pump.----Thermostat has nothing to do with the tell tale.

 

[Trakker]

Thank you, so water pump must be submerged. I know that I am about 4” above pump

 

[Sea Rider]

Was that motor run in salt or fresh open water to start with ?

Happy Boating​

 

[Trakker]

The motors always been in fresh water

 

[Sea Rider]

The motors always been in fresh water

Running in fresh water it's no indication whatsoever that the motor won't collect deposits, layers of whatever is found in fresh water, will do after 33 years of use, but to a less degree than when run on salt water for same amount of years. If a kettle collects deposits on lower base with fresh water, why won't an outboard experience same ? Go for a 15 minute wot run and if the motor overheats there you have it...

Happy Boating​

 

[oldboat1]

Should check the water pump work. Make sure the impeller key is in place, and that the water tube is properly inserted in the grommet (side of the grommet not bent over, causing a partial blockage.) Run a stiff piece of monofilament into the tell tale as far as it will go to see if that solves the intermittent stream.

The tell tale, if working, indicates water is getting up to that point, but not that it is circulating through the engine (re. overheating issue).

If the w.p. is working, and if the water in your test tank is deep enough, overheating would mean removal of the cylinder head and scraping around the cylinders with a flexible knife or similar, resurfacing the mating edge of the head, and replacing the head gasket torquing to spec. Need a piece of wet/dry sandpaper and a flat surface, rotate surface in figure eight pattern until you see an equal shine all around.

 

[Faztbullet]

Those block dont like to be overheated as the aluminum will pull away from cylinder liner . This causes head gasket to leak compression into the cooling area, which as RPM increase the pressure will overcome the impeller flow.