Mercruiser 165 Over Heating, outdrive question

[system-f]

So my Mercruiser 165 with the Chevy 250ci started running a little hot. When I got home I pulled the lower leg and the impeller looks fine. So I am guessing it is the messed up thermostat that didn't look right, but this isn't my quesion. When pulling the lower leg I was trying to figure out how oil got from the bottom gear case to the top. Is it really just that little hole at the bottom center of the picture with green oudrive oil coming out?

 

[Bt Doctur]

Re: Mercruiser 165 Over Heating, outdrive question

And there is a small O ring that goes there.

 

[system-f]

Re: Mercruiser 165 Over Heating, outdrive question

Yeah, the O-ring is on the lower side and looks shot. That's it? that is the only way for water to get in through this section save the shaft oil seals on the lower and upper side?

 

[Bt Doctur]

Re: Mercruiser 165 Over Heating, outdrive question

Forget the O ring and you`ll be losing gear oil too,
prop shaft, shift shaft, water pump base, upper unit drive shaft seal, carrier seal are prime candidates for leaks and water intrusion.

 

[system-f]

Re: Mercruiser 165 Over Heating, outdrive question

UPDATE:

I have installed the new thermostat, impeller and seals, and Trim line. I did forget to put an O-ring on the upper part of the drive shaft so I have to pull the leg again and install the O-ring. We hope to test this today. Here is a picture of my old VS new thermostat. The impeller looked fine so I really hope this is causing the overheating issues.

Installed

 

[hoot]

Re: Mercruiser 165 Over Heating, outdrive question

fwiw, the impeller can look good and still not be pumping water up to the pump on the motor. be sure you have the curve correct on the vanes.