Rebuilt 1974 15 HP Evinrude Not Staying Cool - New thermostat - Fresh Rebuild

[code1p36]

I just rebuilt a 1974 15 HP Evinrude and it is not staying cool even with a new thermostat I just installed tonight. I tested the thermostat and it is opening around 140°-145°. I know it is pumping good water up to the thermostat because I pulled it out along with the cover plate and started it for second and it bubbled out a lot of water. I also know the water was getting to the top of the inside of the exhaust cover because I had a small water leak. After I let the motor run for a bit it slowly started spraying a small mist of water out of the telltale on the back below powerhead on exhaust housing but the head is still too hot to touch more then a second or two so I shut it down. I just went through the whole powerhead with a new set of gaskets and seals and made sure there was no corrosion blocking waterways.

Any ideas what could be the issue?

Thanks.

 

[cyclops2]

Could be a incorrect gasket.

Why did you decide you needed to do repairs to the cooling systewm parts ?

My 95 9.9hp Has a TINYpush pin in the thermostat parts. It is about 1/16" X 3/16" . I lost it without knowing it. after 2 thermostats the marina took pity & had a great mechanic & parts man show me why it kept overheating.

DIY is NOT always possible on everything

Did the old impellor have every rubber part of it still on it ?

 

[code1p36]

Are you sure you installed the impeller correct? When you pushing down on the impeller housing you must turn the driveshaft clockwise. Once the pump in all together you cannot turn the driveshaft counter clockwise. The fins flip backwards and stay that way. When you start it with the thermostat cover off water should gush out with some force. It just sounds like the impeller is messed up to me easy enough fix just remember only turn the driveshaft clockwise the way the engine runs.

I usually always turn it clockwise only and it did have a pretty good gush coming out when I had the plate off. I will check this just in case though. Thanks.

 

[code1p36]

Could be a incorrect gasket.

Why did you decide you needed to do repairs to the cooling systewm parts ?

My 95 9.9hp Has a TINYpush pin in the thermostat parts. It is about 1/16" X 3/16" . I lost it without knowing it. after 2 thermostats the marina took pity & had a great mechanic & parts man show me why it kept overheating.

DIY is NOT always possible on everything

Did the old impellor have every rubber part of it still on it ?

When I pulled the old thermostat it had some corrosion on it and opened at around 165° which is a little high so that is why I replaced it and I looked at it closely while testing it so I think it is fine. I do believe the old impeller was in tact. I completely rebuilt with a remanufactured block so the old impeller is not lodged in there. Makes me wonder if I have an incorrect gasket? I am going to try pull the thermostat and run without it to see if it stays cool. I know they are there for a reason but this will tell me if I have an incorrect gasket. Why is water getting up to the exhaust cover area? Anybody have a cut away waterflow diagram?

Thanks.

 

[optsyeagle]

Here you go. Ignore the "over-board water indicator". It was a diagram for your model of motor that helps explain where to attach a better tell-tale indicator for observing the operation of the water pump. The rest of the flow is accurate.

In any event, when your motor starts up you will not see much water out the exhaust relief hole, immediately. If you put your hand behind there you will feel a slight mist only. In about 10 to 20 seconds the T-stat will start to open and you should observe a good spray. When out in the water you will notice a stream of water moving away from and back to the motor, as you accelerate and as the T-stat opens and closes automatically.

That is how your model operates.

 

[code1p36]

Here you go. Ignore the "over-board water indicator". It was a diagram for your model of motor that helps explain where to attach a better tell-tale indicator for observing the operation of the water pump. The rest of the flow is accurate.

In any event, when your motor starts up you will not see much water out the exhaust relief hole, immediately. If you put your hand behind there you will feel a slight mist only. In about 10 to 20 seconds the T-stat will start to open and you should observe a good spray. When out in the water you will notice a stream of water moving away from and back to the motor, as you accelerate and as the T-stat opens and closes automatically.

That is how your model operates.

The motor is doing just as you described with spraying a small mist at first then a little more later but not as much as other outboards I have seen. I still haven't broken it in yet so I haven't revved it up. Once I test it without the thermostat that will let me know if it is a gasket installed incorrectly.