Normal Temp 1997 Mercruiser 5.7 Bravo 3, 250 HP

[Mr. Impulsive]

Hi,
Brand new to this forum but am a member of a Corvette forum like this which is invaluable. I just purchased a 97 SeaRay 250 Sundancer with a carburated Merc 5.7 Bravo 3 I/O. Can anyone let me know the normal temp that this should be running. When I took it out for the first time it ran above 170 ( about 185)and didn't come down. This was my brother's boat, meticulously taken care of. He had a new thermostat and body impeller installed before shipping it to me. I do not have the engine operators manual with the normal temp referenced in the regular owners manual. I have the merc sterndrive paperwork but it deals more with engine installation and start up rather than specs. I am going down to the boat today with an IR gun to test the temp at the thermostat gooseneck but need to know what is normal. I felt the thermostat housing the day I took it out and it felt cooler than 170 which makes me think it is the guage or sender. Any help to a newbie would be appreciated.
Don

 

[Bondo]

Re: Normal Temp 1997 Mercruiser 5.7 Bravo 3, 250 HP

Ayuh,... Generally speaking,... Boat motor T-Stats are 140? or 160? or with closed cooling, 180?...
So,...
With the info you provided,... It could be any of the 3....

 

[Mr. Impulsive]

Re: Normal Temp 1997 Mercruiser 5.7 Bravo 3, 250 HP

Thanks for the help. I'll check it with the IR gun when I go down and take it from there.

 

[TilliamWe]

Re: Normal Temp 1997 Mercruiser 5.7 Bravo 3, 250 HP

It's a little red apples to green apples, but my 1997 5.7EFI Mercruier had a 160 degree thermostat in it, and it would show about 170 on the gauge.

 

[Mr. Impulsive]

Re: Normal Temp 1997 Mercruiser 5.7 Bravo 3, 250 HP

It's a little red apples to green apples, but my 1997 5.7EFI Mercruier had a 160 degree thermostat in it, and it would show about 170 on the gauge.

TilliamWe,
Thanks for the input.
Don

 

[AZSenza]

Re: Normal Temp 1997 Mercruiser 5.7 Bravo 3, 250 HP

My 1997 22 foot Larson with the same 5.7 250hp Merc shows trhe same thing. It warms up to 170-175 and thats where it stays, all day all night, when we idle down for say 10-15 min it falls off to about 160 but will go back to 170 after a few minutes (I'm assuming thats the therm going from open to partially closed to go back to 170) My boat was also very well maintained by PO and myself. I think its normal. Im reluctant to open it up to check the therm temp.

 

[TilliamWe]

Re: Normal Temp 1997 Mercruiser 5.7 Bravo 3, 250 HP

TilliamWe,
Thanks for the input.
Don

You are welcome. And I just looked at the few pages of my Mercruiser Operation and Maintenance Manual, that I copied before I sold my boat, and all the V6 and V8 engines in 1997 had 160 degree thermostats.

 

[Mr. Impulsive]

Re: Normal Temp 1997 Mercruiser 5.7 Bravo 3, 250 HP

My 1997 22 foot Larson with the same 5.7 250hp Merc shows trhe same thing. It warms up to 170-175 and thats where it stays, all day all night, when we idle down for say 10-15 min it falls off to about 160 but will go back to 170 after a few minutes (I'm assuming thats the therm going from open to partially closed to go back to 170) My boat was also very well maintained by PO and myself. I think its normal. Im reluctant to open it up to check the therm temp.

Checked it with an IR gun and it reads about 160 so it's probably a sending unit issue. I have the same issue with my 65 Vette. Thanks to all for the help. It looks like I'll be a regular on this forum.

 

[TilliamWe]

Re: Normal Temp 1997 Mercruiser 5.7 Bravo 3, 250 HP

Glad we could help. Glad you confirmed it with a technical tool, and welcome aboard!