I have a 15hp Envinrude that overheats while under a load. after running for 5 or so minutes under a load, it runs considerably hotter, the water stream coming from the side cover turns to a dribble. I have replaced the water pump, thermostat, removed head and checked the cooling passages, all clear.
no expert in evinrudes but if the water dribbles there is a problem. option a: impeller sheared from the hub so it it turns and pumps at low rpms but slips at high rpms. option b:somewhere it must be plugged. option c: the engine is too far above the water at high rpms so ther is no water for the impeller to pump. option d: poppet valve opening too soon. do not know if your has one but the spring may be worn or the valve or grommet may be old and distorted. good luck
Welcome - Hopefully you will find the answer here.Your symptoms point to an obstruction in a water passage. You have covered the most likely places if you got the water pickup tube properly placed when you reinstalled the lower unit. Did you try to backflush the motor when you had the head or the thermostat cover off? You can do this by forcing water under pressure up the pickup tube with the head and thermostat cover off. The only other water passage that I can think of is on the exhaust side of the block. You can remove the cover and check there.
The next thing i guess is to remove the powerhead. I back flushed from the thermostat already and even ran the motor without the lower unit attaching a hose to the water tube. I have to remove the powerhead to get the side cover off. Thanks for the replys.I do not know if it has poppet valve. I ran it under a load as well at the dock thinking the same thing that the housing was running out of the water. unfortunatly same effect. Thanks, again.
i have the same motor, although mine is an"economy"version, a 14hp.i have noticed that the motor needs A STRONG, i repeat.. STRONG amount/flow of water to pump and cool properly. try removiong the lower unit and placing a garden hose on the water pickup tube with the motor OFF and see if it pees, if not you have an obstruction.mike
Also, what did the old impeller look like, if it came to pieces before you replaced it, the loose stuff is blocking your passages, I know you said you checked, but how and what did you check? Try removing the thermostat and see what happens. Let us know. Also, check out this site for your motor. http://www.pugetsoundanglers.org/Fis...n%209.9_15.htm
phatmanmike: already did that, can't put it under a load while on the garden hose.knobby: Old impeller was fine, no pieces. Ran it without the thermostat, same issues.P.V.: Didn't think of that, I beleive I have to pull the power head for that anyway since I want to get the side cover off, looks like my next best option.Thanks for the replys.
Thinking outside the box a bit here - is the motor being lugged? If you're running a light runabout prop on the motor and the boat is a fully loaded fishing machine with livewells, coolers, gear, and three or four buddies onboard, it could overheat if you try running it wide open all the time just from working too hard. The 15s like to spin up quite a bit. The max RPM range touches 7000, so if you're lugging it down around 5000, she could cook... Prop it to reve to about 6300 and you should be good to go...- Scott
thats a very basic motor. if youve pulled the powerhead, you can see almost the hole thing. woodruff key missing...?waterpump housing not bolted down properly...?sand in your cooling passages...?(happened to me once)mike
myself 175lbs in a 16' rowboat, not too much of a load. I have used it in the past as a trolling motor on an 18' Starcraft with three adult on it board. It suddenly started the over heating in the spring on the row boat.I am going to pull the powerhead off next, keys, pump and passages I had access to were perfect. Keep you posted.
1988 15hp Evinrude over heating
Linear Mode
