1988 Mercruiser 5.7 thermostat install - did I install this correctly?

lakeaffect

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Joined
Jun 20, 2016
Messages
9
1988 Celebrity with Mercruiser 5.7 and Alpha One

As part of the winterization process, I removed the thermostat housing, cleaned it up and installed a new thermostat (142 degree) - the old one had come apart and the boat was essentially running without a thermostat for several years. I fired the boat up for the first time this season and while at idle the engine appears to be smoking from the back (exhaust manifolds) and was obviously getting very hot - didn't seem quite right - i ran it at idle for about 7min. I shut it down, let it cool and restarted, revved it up a little thinking that might get the water circulating in the engine, but soon got a temp warning light so I immediately shut it down. I'm going to replace the impeller because I'm sure it's overdue, but also wanted to be sure that I did not install the thermostat backwards? The first photos show the old, broken thermostat and the later photos show the shiny new one. The last two photos show the thermostat which gets covered up with a solid gasket and metal plate that the bolts run through and lift hook attaches to. Does the orientation of the thermostat look correct? Thanks for any input.
 

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Bt Doctur

Supreme Mariner
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Aug 29, 2004
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19,474
pics 3 and 4 look correct/ I usually pull the drive when I winterize and insert a washing machine hose cut in half into the inlet opening .This way I dont have to worry about the rpm in case I want to clear the fogging compound out first. Too high of an rpm on a hose can collapse the hose from suction and melt an impeller
 
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lakeaffect

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Jun 20, 2016
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9
Thanks BT Doctur! I'm curious to see the condition of the impeller - i think it's way old. If it looks intact I will have to continue to search for a cause.
 

lakeaffect

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Jun 20, 2016
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9
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I've seen a lot of posts here that don't end with a conclusion so didn't want to be guilty of that - how's this for a worn impeller/cup? Got the new kit installed and engine is now cool as a cucumber!

Thanks for the assistance.
 

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Bondo

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I've seen a lot of posts here that don't end with a conclusion so didn't want to be guilty of that -

Ayuh,.... Thank you,..... ;)
 
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