Thermostat

[62cruiserinc]

I have a 1981 Sea Ray 260 with a Mercruiser 260 5.7L V8 and Alpha 1 Gen 1 (SEI) outdrive.

The previous owner says the engine is a replacement crate engine.

Last fall I winterized the engine and removed the thermostat cover and thermostat so I could fill with AF.

I want to replace the thermostat with a new one.

Which thermostat is the correct one for my engine? In reading some previous threads, it looks like there are several considerations in selecting a thermostat.

Thanks
Steve

 

[alldodge]

The original motor came with a 140 degree thermostat, newer ones come with a 160 degree. Not knowing if the crate motor is an original or vortec.

 

[Scott Danforth]

if your in fresh water, i would run 160 degree stat. if your in salt water, I would run 140 if carbed and 160 if EFI

 

[62cruiserinc]

It's a carbed engine with points and a mechanical fuel pump.

It will be on Lake Ontario, so freshwater.

So I will pick the 160 degree thermostat kit.

Out of curiosity, why do you suggest a different temp for carbed in salt water?

Also, Mercruiser thermostat vs Sierra thermostat?

Thanks
Steve

 

[Scott Danforth]

salt comes out of suspension at above 140 degrees and acts like sand going thru the motor eroding the block, heads and manifolds faster if anything above a 140 F is used.

both Mercruiser and Sierra get their thermostats from Stant

 

[62cruiserinc]

What is the advantage of going to a 160 degree thermostat instead of the factory 140 degree?

I am finding lots of info showing the factory 140 degree thermostat (Sierra 18-3551) but how do I find a 160 degree that fits my engine?

Thanks
Steve

 

[thumpar]

The engine will run better with a 160 since it can get warmer. You can find a 160 thermostat at an auto store. Just tell them it is a chevy 350 and the temp. If it is at least a halfway smart person they can look it up. On mine I think the guy put in a 1960 something car.

 

[alldodge]

If your not in salt water go with 160 degree. The 140 is better for a motor which is open cooled in salt water

Also +1 with thumpar

 

[62cruiserinc]

Ok, I'll try an auto parts store that has an employee that has some real car knowledge (hard to find someone like that!).

So I can't just use the later model 5.7L Mercruiser 160 degree thermostat because it won't fit?

Steve

 

[Bondo]

So I can't just use the later model 5.7L Mercruiser 160 degree thermostat because it won't fit?

Ayuh,.... Sure, they're all the same,....