Replacing 143* thermostat on 120 Mercruiser I/O 52 year old Sea Ray

[redgoat]

I am the original owner of a 1967 Sea Ray I/O with a 153 cu. in., 4 cyl mercruiser engine. Recently I had to replace a badly worn water pump impeller that was causing my engine to overheat. I thought I might as well replace my thermostat as I cannot recall how long it's been since I replaced it. My question is does the spring portion fit UP into the thermostat housing or DOWN into the thermostat housing? See photo. It will "fit" either way but I must know conclusively which way it goes before I finish winterizing with antifreeze. Remember this is a 4 cyl mercruiser that has, so I have been told, a Chevy "iron duke" engine modified by Kiekhaefer. I do not want to ruin my new impeller or damage my engine so I hope someone knows which way it goes inside the thermostat housing. I know how the old one was positioned but is it possible I may have installed it incorrectly all these years?

 

[GA_Boater]

Spring always points to the block because that's what the stat "pill" is sensing - The water temp in the block, not the thermostat housing.

Remember this is a 4 cyl mercruiser that has, so I have been told, a Chevy "iron duke" engine modified by Kiekhaefer.

Nothing to remember cuz it ain't true.

 

[redgoat]

Thanks for the reply. So based on my photo, does the spring point UP or DOWN while situated in the thermostat housing? For many, many years, the thermostat spring has been pointing UP in the housing probably because the thermostat itself would not "fit" with the spring down because of the wide metal sides. Was that correct, or have I been installing it incorrectly? The replacement thermostat does not have bulging metal sides so it could fit either way.