Can I run my motor without a thermostat

[dean pointer]

Can I remove the thermostat in a merc 350 5.7 fresh water cooling system and still run the motor like normal. Will the motor stay cooler. We use to take them out of cars with no problem. Will this work.

 

[stevea661]

if your cooling system is a full one, through the manifolds your boat should run about 180 with a 160 thermostat in it at lower rpms. It should cool off to about 170 as the rpms come up. I have a 5.7 with a full system and that's normal for it. the more water you pump through the heat exchanger the cooler it runs . If you are having a cooling problem check the following, check actual temps with an IR gun. If these numbers jive with your gauge check all the other stuff.

 

[BarryCF]

If it is overheating with a functioning thermostat, it will overheat without one.

Running a boat, or car, engine at lower than designed temps cannot be done without problems. The oil will not work as designed, gumming up and eventually causing catastrophic damage.

 

[sonepheth]

Try it out, I'm curious to know also. I don't have overheating. My engine heat up to operating temp quickly so if I remove the thermostat then it will take longer to reach operating temp?

 

[Summerwind]

I hate to admit this but I've been running my 6.2s with the T-stats stuck open, I haven’t got around to installing new ones, yet. There haven’t been any power issues, however, I humbly ask the boating gods for their forgiveness.

 

[ultratiger89]

I hate to admit this but I've been running my 6.2s with the T-stats stuck open, I haven’t got around to installing new ones, yet. There haven’t been any power issues, however, I humbly ask the boating gods for their forgiveness.

I know many who have had this issue or just ran without them. It will burn more fuel, but they never had any damage to the motors. Of course, I'm in South Texas where the ambient temps are in the upper 90's most of the Summer. I can see were the oil viscosity could be a problem, and if that's a concern, run a less viscous oil.