140 vs. 160 degree thermostat in Salt water?

[enginesilo]

I'm about to change my thermostat and I called a part place and they asked if I wanted a 140 or 160 degree. The sales rep said that in salt water they recommend running a 140 so there is less salt build up at higher temps.

Is this what Mercruiser recommends for a raw water cooling setup? 140 for salt water? I've always seen 160 as the norm in most boats i've been on.

 

[MarkSee]

Re: 140 vs. 160 degree thermostat in Salt water?

I'm not thinking that every model engine Merc. ever made used the same temperature thermostat for either water type so having your engine serial number, model, year would help or here's a link you can plug it into and see what it shows:
https://webapps.brunswick.com/literature/literatureSearch.do

My raw water cooled 7.4 does use a 160 as you mentioned.

Mark

 

[enginesilo]

Re: 140 vs. 160 degree thermostat in Salt water?

Thanks Mark,
The engine is the Mercruiser 3.0L, around 2005
That link didn't allow me to see multiple parts, just one diagram. This is the site catalog I refer to typically:
Serial Range: 0L097000 THRU 0W301999
Marine Parts Plus Mercruiser Serial 3.0L GM 181 I-L4 804862 99

Here is the thermostat page, and I just noticed it says 160:
Marine Parts Plus Mercruiser Serial 3.0L GM 181 I-L4 804862 99 4893-150

So does that mean the 160 is probably standard no matter salt or fresh?

 

[MarkSee]

Re: 140 vs. 160 degree thermostat in Salt water?

Yes, I've not heard anything ever mentioned about using a different temp thermo for salt vs. fresh water use as many a boat is used in both.

There sometimes is a difference if your boat has a closed cooling system with a heat exchanger that might use a different stat than raw water cooled but not a difference in the type of water.

Mark

 

[achris]

Re: 140 vs. 160 degree thermostat in Salt water?

The engine is the Mercruiser 3.0L, around 2005

The correct thermostat for YOUR engine is 160?.

Higher temperatures lead to more acid deposits in the engine exhaust (sea water disassociates into HCl, hydrochloric acid, under high temperature).... With the advent of stricter emission laws, the need to keep acid out of the exhaust has been overridden by the need to keep oxides of nitrogen down, and the way to do that is to run the engine hotter.... (it does also make the engine run more efficiently too)....

HTH,

Chris........

 

[tpenfield]

Re: 140 vs. 160 degree thermostat in Salt water?

Perhaps more of a myth than fact, as to what the sales rep is referring to. You can Google "high temperature corrosion", but if it were a real issue, the engine manufacturers would advise accordingly.

 

[Lou C]

Re: 140 vs. 160 degree thermostat in Salt water?

Ive heard the 140/salt 160/fresh thing for years now and Ive run a 160 in salt more than 10 years and have not had clogging of the cooling system as of yet. I was not ever able to find a 140 for the OMC thermostat housing design.

 

[Fun Times]

Re: 140 vs. 160 degree thermostat in Salt water?

The engine is the Mercruiser 3.0L, around 2005. So does that mean the 160 is probably standard no matter salt or fresh?

In your case yes, especially since your engine model should be equipped with the TKS (Turn Key Start) carburetor. There are certain variations in engine temperature that need to be within a range for the system to work properly and 140 degrees is actually a bit to cold for this system to work properly.