79 JOHNSON 100 V4 RUNNING HOT

[FRYE8633]

HELP, 79 JOHNSON 100 V4 RUNS HOT. WE HAVE CHANGED THE WATER PUMP ASSEMBLY. CHECKED THE HOSE GOING UP. BLOWN IT OUT. IT PUMPS WATER OUT OF PEE HOLE AND EXHAUST HOLES BUT ABOUT 15 MINUTES IN WATER THE ALARM GOES OFF. CHECKED ALARM, BUT THE ENGINE IS EXTREMELY HOT. <br />ANY SUGGESTIONS?

 

[Goodoleboy]

Re: 79 JOHNSON 100 V4 RUNNING HOT

Welcome to the forum!<br /><br />Sounds like you have a thermostat thats stuck closed. Which bank seems hottest. But if I were you I would change both.<br /><br />Good Luck!

 

[FRYE8633]

Re: 79 JOHNSON 100 V4 RUNNING HOT

Hi,<br />We already looked at that, The boat repair shop took those out years ago.<br />Thanks, <br />Any other ideas?<br />S

 

[Goodoleboy]

Re: 79 JOHNSON 100 V4 RUNNING HOT

You may have got something stuck in the water passages inside the block is my next guess.<br /><br />If it were me I would put those thremostats back in. Motor running to cold is not nearly as bad as one running to hot thats for sure.<br /><br />But running to cold will also kill the motor. Just takes longer.<br /><br />Drop the lower unit and duct tape a garden hose to the water inlet tube going up to the motor. Remove water passage cover. Look at the water deflectors little rubber finger like things. one or more may have broken off and lodged someplace.<br /><br />Good luck!

 

[FRYE8633]

Re: 79 JOHNSON 100 V4 RUNNING HOT

Hi,<br />I also needed to add that it seems to never run hot on the hill. Only after putting in the water and running for 15 to 20 minutes does the alarm sound. <br />On some other message I read this may be due to backpressure?? Please explain.<br />Thanks,<br />S