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1979 johnson 6 sea horse

S

Slowswimmer6

New member
I just got this motor for free. It has been sitting for 3 years and still runs fine, except for the cooling system.
I replaced the water pump impeller which was bad, and blew out the lines with air, but am still not getting the water to circulate and the engine is overheating.
Could this be a thermostat issue? Or does anyone know what could be causing this issue?
 
Hi. Is it a saltwater use motor? If so, you may need to check the head gasket....not a bad idea anyway as they sometimes blow across between cylinders. A compression test might show this by low compression near duplicate on both cylinders. Also something of note would be to see if there was any particles missing off of the impeller which might be lodged up stream?
 
In a test bucket the water must be 6" above the impeller.----Put thermostat in boiling water to see if it opens.-----Have seen some thermostats that were stuck closed.
 
From easier & little $$
How deep is the water in your test bucket- it MUST be around 6” above the impeller,they are not self priming.
Unbolt the thermostat & look at it…1 minute, 3 bolts. Clean passages if full of gunk. Test thermostat in pot of water & cooking thermometer.
Re-visit your impeller fix. Is the water intake screen plugged? Is the copper tube inserted at both ends? Is the impeller housing scored up, did you ensure the little pin, (#17) is engaged with the impeller?
You can spin the drive shaft with a drill while bottom end immersed- if you don’t get good flow, revisit your water pump.
 
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