Jupiter Dinghy
Regular Contributor
So I took the 20 HP (J20CRCEM) for a test ride after a carb rebuild and a water pump replacement (for the record this is a motor I bought recently and that spent the last 3 to 4 years unused, so i really don't much about its history).
In the barrel, I had a nice full stream coming out of the pee hole, and water coming out of the exhaust housing, so I thought it's cooling good, let's give it a run, because it needs to run badly.... (lots of that black gooey stuff coming out of it through the gear case hole, which is understandable after this long sitting period).
Got to the ramp, started right up, with water coming out the pee hole , so off I go to give it some full throttle action.
It ran flawlessly for about 2, maybe 3 minutes, and then started misfiring. I rolled the throttle down, and was able to keep it idling, but as soon as I would try opening the throttle some more it would start misfiring again.
I notices the water stream from the pee hole had become just a drip, but water was still coming out of the exhaust holes, however, it got much hotter to the touch. Very hot in fact.
So I keep idling along after making a U-turn to head back to the ramp, and after running idle a while, I notice the pee hole stream was back as it should be, and the water temp had come back down to warm, but not "hot".
Back at the ramp, I take the hood off, and touch the head: Burning hot. Couldn't keep a finger on it at all.
So I'm thinking the motor fooled me into thinking it was cooling fine in the test tank, but under load, it cools for only a couple of minutes and then starts overheating.... sounds like the thermostat right?
So back home I take the head cover off and sure enough the thermostat, could hardly be seen beneath the crusty stuff that covered it entirely. It's definitely done for.
First question: I see on the exploded view that there is also a "temperature switch" encased in the head. Is there a way to test it, or should I replace it along with the thermostat anyway? And if so how do I remove it from there? I don't want to pull on the wire as I think it will break...?
Second question: Can I start the motor with the cover and thermostat removed just to confirm that water is flowing fine to the thermostat housing?
Third question: On the pic below, you will see the 2 holes located in the front of the exhaust housing, and exposing the drive shaft to water.
Are these holes supposed to be open like that? Are they part of the cooling system? Thanks.
In the barrel, I had a nice full stream coming out of the pee hole, and water coming out of the exhaust housing, so I thought it's cooling good, let's give it a run, because it needs to run badly.... (lots of that black gooey stuff coming out of it through the gear case hole, which is understandable after this long sitting period).
Got to the ramp, started right up, with water coming out the pee hole , so off I go to give it some full throttle action.
It ran flawlessly for about 2, maybe 3 minutes, and then started misfiring. I rolled the throttle down, and was able to keep it idling, but as soon as I would try opening the throttle some more it would start misfiring again.
I notices the water stream from the pee hole had become just a drip, but water was still coming out of the exhaust holes, however, it got much hotter to the touch. Very hot in fact.
So I keep idling along after making a U-turn to head back to the ramp, and after running idle a while, I notice the pee hole stream was back as it should be, and the water temp had come back down to warm, but not "hot".
Back at the ramp, I take the hood off, and touch the head: Burning hot. Couldn't keep a finger on it at all.
So I'm thinking the motor fooled me into thinking it was cooling fine in the test tank, but under load, it cools for only a couple of minutes and then starts overheating.... sounds like the thermostat right?
So back home I take the head cover off and sure enough the thermostat, could hardly be seen beneath the crusty stuff that covered it entirely. It's definitely done for.
First question: I see on the exploded view that there is also a "temperature switch" encased in the head. Is there a way to test it, or should I replace it along with the thermostat anyway? And if so how do I remove it from there? I don't want to pull on the wire as I think it will break...?
Second question: Can I start the motor with the cover and thermostat removed just to confirm that water is flowing fine to the thermostat housing?
Third question: On the pic below, you will see the 2 holes located in the front of the exhaust housing, and exposing the drive shaft to water.
Are these holes supposed to be open like that? Are they part of the cooling system? Thanks.