[pieps57]

I have a 1973 18 hp evinrude that is over heating...

Now is it for sure the water pump?
Can you tell if a water pump is bad when you pull it?
Im not exactly sure how the cooling system works on boat motors...

There is some water coming out of the hole its suppused to on the back of the lower unit ......

Any help is greatly appreciated..

Thanks

[bktheking]

No not for sure, yes usually you can tell , the vanes on the pump are broken/distorted, could be the pump housing or plate it rides on, could be a blockage in the cooling system as well. Most motors have a thermostat, i'd pull that out and check to see if it's functioning in a pot of boiling water and a thermometer. Mist coming ou the back is a good thing but it all depends on how much mist, a good pumping pump should puke water out that hole, not spray bottle type mist.

[Daviet]

How long have you owned this motor? If the pump has not been changed in the last 2 or 3 years, it is time to do it anyway. Be sure to check stat if your motor has one. What year is your motor?

[bktheking]

He said it's a 1973.

[pieps57]

So where is the thermostat on it?
and what do i do to check if i need to "unclog" the coolant system?

[Rick.]

For thermostat location check this link. Actually you can learn lots about your motor just viewing the parts breakdown but an OMC service manual for your specific model and year is a valuable asset.
http://shop2.evinrude.com/ext/index....5dbcb952e42681

If the system is plugged up there could be several steps required including pulling the head, but do the impeller first. That will normally be all you need do. I would pull the impeller and check the condition of the pump housing as if it is scored and/or badly worn it should be replaced at the same time. Best of luck. Rick.