1969 Johnson 25 horse model 25RL69D Engine Questions

[Roscoe_Floyd]

Hi everyone,

I got my boat motor running again, thank god for Sea foam wow, what good stuff. I do have some engine questions. I got a tub and ran my engine in it for an hour and I notice when the engine was in neutral that the water pump ran off and on and I was under the impression that if the motor is running the pump
should always be running. I put Deep Creep in the carburetor and wanted to get it all out so I revved the engine, I think the pump finally stopped don’t know why. The Deep Creep smoked the place up and the engine finally died I felt the engine and it and it was hotter than all get out. It idled great and ran like a top for an hour. Needless to say I'm learning about all this I and have few more questions.

1. Should I be running the engine for an extended amount of time in a tub of water? Or should I keep it down and just make sure that the engine is running ok. This means there is no substitute for running the engine in a body of water under a load. It's been very embarrassing to have the boat die in the middle of the lake and someone tow me back to the dock.

2. I thought the water pump should run constantly. Is this the case? The pump seemed to run constantly
when the boat was in gear, just not so much in neutral. It is not impossible to run it in gear but easier to run in neutral in the tub.

3. Why did the engine get so hot? Do I need to replace the thermostat? I don’t want to burn up my
engine up, if the thermostat was working correctly shouldn't it have shut the motor down sooner or kicked the water pump on more often to keep the engine cool?

Thanks for all your suggestions and help.


Roscoe

 

[F_R]

Re: 1969 Johnson 25 horse model 25RL69D Engine Questions

So how deep is the motor in the tub? It needs to be deep enough to submerge the water pump. The propeller is force-feeding the pump while in gear. It sounds like it is losing it's prime in neutral (because it is not deep enough). Also, the air in the water interferes with proper cooling. Your motor was engineered to run on a boat.

Yes, the water pump turns anytime the motor is running.

Thermostats do not "shut the motor down" Motors siezing up from overheating "shut down" as they burn up and self destruct. Nor do thermostats "turn the water pump on". They only open and close to change the direction of water flow through the cooling system....but it is flowing all the time. Thermostats fail in the open positon, not closed. One reason they fail is engine overheating from water pump failure. If it isn't popped open, cold, it should be OK.

If your motor got hot enough to fry the paint on the head, you should replace the head gasket. If it didn't get that hot, at least retorque the head bolts.

 

[Roscoe_Floyd]

Re: 1969 Johnson 25 horse model 25RL69D Engine Questions

Thanks I thought I did'nt have the water deep enough. No it didn't get that hot. I put the water up to the base of the engine where I thought the water draw was and I noticed there were some holes that were exposed.

I do have it mounted on my boat and drop it down to the tub any advice how deep I should make it or just as deep as I can get it?

Again thanks

 

[F_R]

Re: 1969 Johnson 25 horse model 25RL69D Engine Questions

See the bulge where the bolts are, a few inches above the anti-cavitation plate? The water pump is in that bulge. Have it submetged.