'85 Evinrude 25hp still overheating.

[Trickle56]

Well I'm back again fellas. Here is my original post. http://forums.iboats.com/showthread.php?t=524479&p=3553663#post3553663
Anyway since then I got a new thermostat which was my hunch in the first place along with a new gasket for the water jacket cover. But to my surprise there was no thermostat. But the motor is still overheating within 5 min of it running at a fast idle. It's getting up to 200 degrees with my IR thermometer. I will say that the water pump still maybe acting funny. When I have it in a test tank I get plenty of water from the exhaust ports but little from the tell tale kinda spurts and dribbles untill I bring the RPM's up it pees ok a solid stream anyway. Not as strong as I remember before with the old water pump even at idle. So to single out the pump I hooked up ear muffs to it forcing water through it pees great. But it still getting up to 200 degrees. Thanks for any input guys.

 

[Trickle56]

If water is cycling through the motor it shouldn't be overheating right? I'm shooting my IR thermometer at the powerhead it reads 200 degrees and his scolding to the touch. Somebody has too know something.

 

[nwcove]

Re: '85 Evinrude 25hp still overheating.

as you probably already know, the cyl head will get very hot, as well as the exhaust area. have you tried pointing your ir gun at other areas? ( i have seen motors..had one myself...that had head gasket issues, but would start perfect, idle nice yada yada, but would blow steam out of the pee hole and exhaust relief.....hot exhaust gas will enter the water jackets, add bubbles, work against the pump, and make a motor run hot)

 

[Trickle56]

Sounds a lot like my motor. Did you just replace the cylinder head gasket and to fix your problem?

 

[Haffiman]

Re: '85 Evinrude 25hp still overheating.

Start by pulling down the gear case, attach the water hose straight to the water tube and start the engine. Still getting hot? Probably need to remove the powerhead and check the water grommet and maybe the water deflectors in the cylinder part.

 

[Trickle56]

Thanks Haffiman. I'll give it a try.

 

[tosoutherncars]

Re: '85 Evinrude 25hp still overheating.

What's your compression like? (Didn't see it mentioned.) If it's a problem with the HG, it might be reflected in your compression numbers...

 

[Trickle56]

I checked compression a year ago when I first got it when I had a heck of an ignition problem I was trying to trouble shoot. Then the compression was 120 and 125. I know I should have checked compression after the decarb but I didnt have any gauges. Untill nwcoves motor he spoke of sounds incredibly similar to mine. Your right before I go hacking back in their I'll test compression get an idea where it's at.

 

[tosoutherncars]

Re: '85 Evinrude 25hp still overheating.

Another (perhaps unnecessary) suggestion; when you're running it in a tank, are you bringing the water level up almost to the exhaust (that is, well above where it would run in the water)? There is much less back-pressure in a tank; the impeller (as I understand it) won't draw enough water if you're only submerging the foot to the cavitation plate.

 

[nwcove]

Re: '85 Evinrude 25hp still overheating.

Sounds a lot like my motor. Did you just replace the cylinder head gasket and to fix your problem?

yep, just did the head gasket....think it was $8, completely solved the issue.