59 EVINRUDE 18 overheating

[twocyclemania]

My 18 Evinrude began overheating and I removed the thermostat which was stuck. She made it back to the dock after I took the thermostat out and appeared to run as she should. I went on to replace the impeller and after a number of tries in the barrel she still is overheating. I took the lower unit off and put it in a 5 gallon bucket and turned the shaft with a drill; she's pumping. I poured water into the (upside down motor) copper line that connects with the pump and water flowed through the power head and on out. I took the new thermostat out and ran it with the thermostat cover off and had water coming to the housing and spewing about. Water is pumping out the exhaust but it's very hot (especially considering there's no thermostat right now) and when in neutral nothing comes out the leg exhaust. Any ideas as to why she's overheating? thanks

 

[HighTrim]

Re: 59 EVINRUDE 18 overheating

Either the grommet on top of the impeller housing is swollen, or the copper water line is pinching it, restricting flow, or you have an air leak at the pump housing. Did you seal down the impeller wear plate? Was the vent hole open and clear? Condition of upper grommet?

 

[twocyclemania]

Re: 59 EVINRUDE 18 overheating

Thanks High Trim: Question! I've never heard of sealing the impeller plate. I've always just popped it in and mounted the pump housing. What is the process? I'm going to drop the lower again and check out the vent hole and for good measure replace both the housing grommet and the upper grommet (though they look ok). The oddball thing is that exhaust coolant flows from the leg only when in gear and even then (with the thermostat removed) it appears to be pretty hot. I'm inclined to think there's a restriction somewhere but why would all this happen right after a stuck thermostat? Why would I get water pumping with the drill and be able to pour water through the motor? The motor has really low hours and has always been a great runner and used in fresh water.

 

[HighTrim]

Re: 59 EVINRUDE 18 overheating

It is strange. The t stats almost always stick open. Not closed.

I personally use my 3M847 under the impeller wear plate. Run a bead along the casting where it will hit the plate, then drop plate down. OMC Gasket Sealing Compound on the screw threads for the housing.

Are you certain it was a stuck t stat? Perhaps pump sucked up some debris which is lodged in there>?

The output of the pump will seem warmer in a barrel, as it is cycling a small volume of water, but sure you know that.

Have you actually measured the temp of the powerhead? Will water sizzle when you splash it on the head? Can you hold your fingers on it for a 3 count? Infrared thermometer will give an actual temp if you have one.

Not certain just trying to brainstorm out loud here. The main issue is the obvious, that you have to water flow in neutral. To that I would think weak impeller, worn plate/housing, blocked vent, swollen grommets, or air getting into pump.

Maybe Frank has a more definitive idea.

 

[twocyclemania]

Re: 59 EVINRUDE 18 overheating

Yes the thermostat was stuck when I was cruising up the river. I pulled it right there and than and everything seemed fine as I continued on. As for the barrel I know that can heat up but it's been in the 40's here and I only ran it a few minutes. The motor temp is definitely hot. I did the water head sizzle test and it did indeed sizzle. My hand on the head test also failed - hot. I'm going to try your sealing method after I start from scratch. The impeller is new. I'm going to try new grommets. Usually a cooling system is cut and dry but this one has me baffled and this is one nice low hour motor. Thanks for the advice.

 

[HighTrim]

Re: 59 EVINRUDE 18 overheating

Sorry couldn't give you a more definitive answer. Sounds like you did all the standard troubleshooting. Let us know what you find.

 

[kbait]

Re: 59 EVINRUDE 18 overheating

Also, make sure the impeller plate isn't bent/warped at all.. it'll lose it's seal and not pump correctly if it's not flat.

Good luck!

 

[kfa4303]

Re: 59 EVINRUDE 18 overheating

This may help.

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