Engine overheating,so i removed water pump.

[martyc@tinet.ie]

1972 Evinrude 125hp
Impeller looks perfect.
Base plate has some scoring in it where the outerpart of the impeller would be changing shape....nothing drastic but could this be the cause?? Impeller housing looks fairly good however it is a little eroded loking..anyone ???
Marty

[Greg Moss]

that thing had the old pot metal housing? You should change it out for the new plastic housing and the stainless steel plates.I am not real sure what OMC was tring to do back then with the two water tubes. They used it to mix the cooling water with fresh till the motor warmed up. I think Never really under stood why they did that the way the did.Have you figured out any way to check the temp yet? Of the two water tubes that go to the pump one is cool water coming back from the power head and the other is fresh water and the return water mixed and pumped back to the power head. The water is pumped to the power head and is routed back to the t-stat housing where until the water get to 130 degrees it is routed back to the pump to be mixed with the fresh water and recirculated til it gets to 145 degrees then it is expelled over board. If you knew what tube was the water in you could hook a hose to it and see if it still ran hot. Have you tore the t-stat housing apart yet to look? May be stuck t-stats? I hope you don't get to confused with all this. Greg E-mail me I may be able to help after you get some way to check temps.

[martyc@tinet.ie]

I already have a good understanding of how this pump operates With respect to the 2 hoses) and i have a hose hooked up to the fresh water tube as we speak...i will run it this evening and see if it still overheats...When i say it overheats i mean that the cylinder head is too warm to keep your hand on.If as you say the water is allowed to get up to 140 degrees or so shouldnt the cylinders be getting unbearably hot and still be within operating specs????
PS I have changed Cylinder head gaskets,2 piece head gaskets,Exhaust plate gaskets,T-Stat,and T-Stat housing gaskets.
How do people normally check the engine Temp???ia can be resourceful!!!

[Greg Moss]

I have sereral ways 1 is a RAYTEC Temp probe it is laser sited and no comtact. 2 I have a thermal couple that goes in my FLUKE meter. Or you my find some thermal melt sticks though they only tell you what temp it melts at not how hot the motor is running

[martyc@tinet.ie]

Where should i be putting the thermocouple and what temperatures should i be seeing??
Cheers.
Marty

[Greg Moss]

I check the temps of my motors on the base of the plugs and the water jackets both. Compare the two and it lets you see how well the cooling system is pulling heat from the motor. On any of my motors I don't run them that hot I like to see the base of the plugs run between 105-120 max. idleing.