Having tough time determining which thermostat I need

[Nextelbuddy]

my engine is a 3.0lx mercruiser serial 0F604166.. at least thats what is on the paper from the previous owner. I havent actually looked on the engine itself for that number or know where to find it.

I looked on both:

https://www.perfprotech.com/mercury-marine-parts-catalog/searchserial?search=0F604166

http://www.marineengine.com/parts/mercury_marine_parts/sn/0F604166/430L100JS/2330_90

and both are showing completely different cooling systems that I have. the diagrams dont represent what mine looks like nor do I have a closed loop system.

I have a picture of my engine and you can see the thermostat housing looks nothing like theones in the above exploded diagrams.

I ordered a thermostat from Amazon based on a Sierra marine part# i found for my engine and they sent me 18-3550

https://www.amazon.com/Sierra-18-3550-Thermostat-Mercruiser-Outboard/dp/B00027H2F2

and it does look like the one that came from my engine but it looks super small and came with no gasket. (like an idiot i threw the bad old crusty thermostat away so i cant compare side by side)

i've been scouring youtube videos and google image search and i cant seem to have good luck finding someone else with my thermostat housing configuration.

Would anyone be able to look at the photo of my engine and see the thermostat housing and know which thermostat i need?

I also need a thermostat housing gasket because the housing is leaking between the 2 halfs and filling the bilge

and anyone happen to know why my engine serial number is pulling up different diagrams online?

 

[Bt Doctur]

That is the correct one

 

[achris]

Merc number is -59078, which that sierra 18-3550 crosses to.

I don't see your serial number pulling up different engines. The drawings for that serial number group includes the engines with the closed cooling option, that's where you might be getting confused.

Chris........

 

[Alumarine]

On a side note, if that yellow tube that looks like it's coming from the carb goes to your fuel pump then it should be clear tubing.
That's so you can tell if your fuel pump diaphragm is leaking and it's dumping fuel into the carb.
It does that so the fuel doesn't leak into the bilge and cause an explosion hazard.

 

[Nextelbuddy]

On a side note, if that yellow tube that looks like it's coming from the carb goes to your fuel pump then it should be clear tubing.
That's so you can tell if your fuel pump diaphragm is leaking and it's dumping fuel into the carb.
It does that so the fuel doesn't leak into the bilge and cause an explosion hazard.

interesting ill take a closer look. I think it MAY be clear but yellowed from old age or discoloration from the inside possibly lol but I will double check for sure.

thanks everyone for the help, very excited to use this information on the boat this weekend.