1974 50 hp Evinrude cooling problems.

[88evinrude]

Ok folks I need some help. First off do any of you have a clear picture of the impeller housing installed on your lower unit. My engine has an over heating problem and even after a new impeller housing and plate the issue persists. I'm thinking maybe I have something installed wrong Ive installed a few on my v4 engines without trouble but this issue is being stubborn. I would also like to ask what else would you check. The screens are clear as far as I can tell. I'm thinking blowing water through the water tube may help as well. Thanks for any help. Oh and the model is a 50443M.

 

[jimmbo]

Is the overheat horn sounding? Test the sensor to see if it within spec. Otherwise, stuck thermostat, stuck pressure valve in cooling system, clogged cooling passages, bad head gasket, problems with exhaust gas getting into cooling system, too much ignition advance, damaged or missing grommets for the tubes, are some things that come to mind,

 

[88evinrude]

Is the overheat horn sounding? Test the sensor to see if it within spec. Otherwise, stuck thermostat, stuck pressure valve in cooling system, clogged cooling passages, bad head gasket, problems with exhaust gas getting into cooling system, too much ignition advance, damaged or missing grommets for the tubes, are some things that come to mind,

Yes the horn did sound and I'm thinking its right because the head will get water sizzling hot and is hot to the touch. Ill start with the thermostat and move up after I make sure the pumps correct. Thanks for the info

 

[jimmbo]

You said you replaced the impeller housing and plate, did you replace the impeller? What about the key/pin/tab that engages the impeller to the driveshaft?

 

[88evinrude]

You said you replaced the impeller housing and plate, did you replace the impeller? What about the key/pin/tab that engages the impeller to the driveshaft?

It was all replaced with new parts.

 

[88evinrude]

I think I found my problem.The thermostat was stuck closed and I cleaned some gunk out of the water tube. I have a marine parts shop about 20 minutes from the house so I have a new one to go in. I will try to run it tomorrow and see if that fix the problem.

 

[jimmbo]

Hopefully that solves it.

 

[88evinrude]

Well I installed the new thermostat this morning and so far it has ran on the muffs without overheating. I still haven't checked it in a tub though.

 

[88evinrude]

I think the problems fixed now. Thanks for the help. https://www.youtube.com/watch?v=KFYoOL3wGuo