Hey guys,
I recently picked up a 1975 15hp for pretty cheap off of craigslist. It would run, but took way too long to get started and wouldn't really idle well. I rebuilt the carb and that helped a little but not much. Compression was 110 on both cylinders and spark was strong (put in some new NGK plugs). Then I noticed that no water was pumping through the water jacket. Replaced the water pump (impeller had broken off a few vanes) but the block was still getting super hot. I hooked up a garden hose to the water pickup tube to see if there was a blockage, and it appears there was. Most of the water was coming out near the bottom of the powerhead and into the lower cowling. So I took the whole thing apart to try and find the issue. All the water passages looked free of debris, I purchased a new gromet for the water pickup tube thinking maybe that was the issue. Thermostat looked pretty gross as well so I replaced that too. I bought a carb cleaner wire set to clean all the orifices in the carb this time, and it turns out there was some junk lodged in the low speed jet! Hoping cleaning this out will fix the idle issue.
Now my question is, how do I clean all these parts before putting it all back together with the new gaskets? There are pieces of old gasket and other crud that's really baked on there, probably since 1975. I don't want to take a razor blade to the aluminum if I don't have to. Any suggestions? Someone on another forum mentioned simple green and a brass brush, ut I've heard mixed reviews on using simple green on aluminum.
Thanks in advance for your help.
I recently picked up a 1975 15hp for pretty cheap off of craigslist. It would run, but took way too long to get started and wouldn't really idle well. I rebuilt the carb and that helped a little but not much. Compression was 110 on both cylinders and spark was strong (put in some new NGK plugs). Then I noticed that no water was pumping through the water jacket. Replaced the water pump (impeller had broken off a few vanes) but the block was still getting super hot. I hooked up a garden hose to the water pickup tube to see if there was a blockage, and it appears there was. Most of the water was coming out near the bottom of the powerhead and into the lower cowling. So I took the whole thing apart to try and find the issue. All the water passages looked free of debris, I purchased a new gromet for the water pickup tube thinking maybe that was the issue. Thermostat looked pretty gross as well so I replaced that too. I bought a carb cleaner wire set to clean all the orifices in the carb this time, and it turns out there was some junk lodged in the low speed jet! Hoping cleaning this out will fix the idle issue.
Now my question is, how do I clean all these parts before putting it all back together with the new gaskets? There are pieces of old gasket and other crud that's really baked on there, probably since 1975. I don't want to take a razor blade to the aluminum if I don't have to. Any suggestions? Someone on another forum mentioned simple green and a brass brush, ut I've heard mixed reviews on using simple green on aluminum.
Thanks in advance for your help.
Last edited:
