77 70hp Rude Still overheating

[dwbrayton]

1977 70hp Evinrude is still overheating after replacing the impeller, Checked thermostat (OK) & flushed from the pickup tube to thermostat. When running the motor, Water does not come out of the outlet but I can see no obstructions anywhere. (I wasn't able to effectively flush the return side of the cooling system without removing the thermostat again.) I guess I still need to try to do that.<br /><br />Any ideas what might be obstructing the flow & how to remove it without pulling the powerhead??? <br /><br />Thanks

 

[jim_in_day]

Re: 77 70hp Rude Still overheating

2 thoughts, First, you said that you flushed the line from the pickup tube to the thermostat. Did you do that by placing a hose over the pickup tube and running water thru it until it came out the thermostat housing? and Second, did you rebuild the pressure relief valves? I modified my side plate and added a tapped hole for an indicator, so i can see water flow out and know for sure that i am getting water thru my motor

 

[dwbrayton]

Re: 77 70hp Rude Still overheating

Yes to the first question & no to the second. Thermostat tested good in the heated pot & pressure relief valves appeared to be servicable.<br />Where did you drill that hole?

 

[jim_in_day]

Re: 77 70hp Rude Still overheating

My buddy has a 78 75hp stinger, thats when they started using the indicator. I measured where his was on the side plate( standing behind the motor, on your left.) I'm not at the shop right now, but I will be friday. I will get measurements then and post. The plate is very thin, I tapped it and installed a 90* plastic fitting with a hose barb on the non threaded side, and drilled a hole in the housing about where the factory put the indicator and then installed the plastic restrictor just like stock, <br />except for the fact that the side plate doesn't have a raised boss where i put the hole, it looks stock.<br /><br />Also are you sure that when you slide the LU in place after the rebuild that you got the water tube into the water pump, I still triple check that every time I do a water pump, because it is so easy to miss.

 

[dwbrayton]

Re: 77 70hp Rude Still overheating

Thanks Jim,<br />My side plate has the raised boss but it is not drilled or tapped, yet. <br /><br />Yes I made sure the tube goes into the pump outlet. It would sure be easy to miss though. <br /><br />I'm just afraid I'm going to have to bite the bullet & pull the powerhead anyway. Only a couple more things to check.