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Trouble shooting 1979 4.5 Mercury cooling

M

Mickeyfinn

New member
Well, I am stumped. Installed new impeller and housing on pump. Tested pump by spinning drive shaft prior to putting back in motor and looks good. Tank tested and there is nothing coming out of tell tale but steam and the occasional spit of water. Is there a way of back flushing the system thru the entire system in case of debris stuck somewhere in the entire system? I hate to think there is something plugging the motor water jacket. Any trouble shooting suggestions appreciated!
 
I'll bet it does NOT overheating, right?

The Tell Tale on those plugs easily. If you have compressed air, give it a reverse flow shot of air and all will be well.

Jeff

PS Those are great running little motors!
 
I would say ( on severe overheat ) the plastic washer at the top of the water tube is melted.-----Factory replacement is a better material.------Easy to remove powerhead for inspection.
 
Also if that engine has a stop button, don't use it. Always flip the choke to shut it off. It has an interesting ignition system that when you push the stop button it actually opens the circuit and overtime can cause damage to very expensive ignition module.
 
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