Cooling Problems

[brycebell]

Hey Guys. I bought a 1974 25hp last year for cheap and only had it out once and it started to get really hot and barely spit any water out of the telltale so i instantly shut it off. I looked at it a few weeks back and noticed that the thermostat was stuck shut so i swapped it out with a working thermostat. The water tube grommet was also plugging the impellar housing, so i replaced it. The impellar is brand new and the impellar intake also seems to be clean and free from any clogs. Once i changed these i figured that i had it figured out and it would be spitting water out no problem, but the water was still barely coming out and was very warm. Im not exactly sure where to start looking for a clog, or how to go about it, so any help would be greatly appreciated. Thank you in advance.

 

[schematic]

Re: Cooling Problems

was the impellar housing in good shape? Did you inspect it for wear and clogs in its weep holes?

 

[brycebell]

Re: Cooling Problems

The impellar housing appeared to be in good shape. which holes are the weep holes?

 

[brycebell]

Re: Cooling Problems

I took the weep holes as the hole in the leg where the water comes out of. These holes do not appear to be blocked and they are free from any obstructions. any other suggestions. i really want to avoid taking everything apart. Does compressed air work at all? Sorry for the stupid questions but im a newbie. Thanks.

 

[OptsyEagle]

Re: Cooling Problems

I am not familiar with the 1974 25 HP but I am very familiar with the 1974 15Hp. In the 15Hp the tell tale water comes out the exhaust relief hole on the back of the midsection. The problem is that very little water comes out until the t-stat opens. If I fire the motor up, I cannot see any water for about 20 seconds and then I only see a light spray of water. When running, after the motor warms up I get a much better spray that increases and decreases as the t-stat opens and closes. That's just the way the design works. If you put your hand under the exhaust relief hole immediately upon start up you can feel a very fine mist of water, proving that water is at least getting up there.

Anyway, my point is, that it is very likely the design of the 25Hp is the same. So did you give it longer then 20 seconds or so to verify that no water was coming out. Could you put your hand on the cylinder head for 3 seconds or more to verify if it was overheating or not.

Also, if you are running it on muffs, my motor will never spit out water from the exhaust relief, even though it is cooling just fine. Why, I have no idea and hence I always use a barrel full of water to test my motor. I gave up trying to figure out why.

 

[brycebell]

Re: Cooling Problems

Thank you for the response! The motor seems similar to that, except for the fact that i started to see water immediately, not just after 20 seconds. i definitely ran the motor for more than 20 seconds but it was just sitting at the dock in neutral. The water coming out of the exhaust relief hole got to be very hot after a couple of minutes and the block was also hot, which scared me. The first time i took it out i never really checked if the water coming out was hot but after 5-10 minutes on the water the engine died in idle and would not start back up until it cooled down.

Maybe i didnt give it enough time to warm up to get more water coming out of the tell tale? But i didnt want to leave it too long and ruin the motor. So now i dont really know where to go to figure out if there is a block or what exactly to do. any help would be awesome. Thanks in advance.