Engine Temperature

[flyboy]

I have started my engine (5.7 V8 mercruiser Ser No 0D501645) for the first time this year and while doing general post winter maintenance and checks i noticed that the engine temperature gauge was reading 170 degrees. Is this normal? I cannot remember the readings i was getting last year but according to the maintenance manual the thermostat opens at around 143 degrees. I am still trying to get my head round the cooling system on my engine so and advice/information would be appreciated.
Many thanks

 

[brimanst]

170 sounds right for a gas motor. Usually the thermostats are rated for 160 and they run about 10 degrees over that. This is just from my previous experience with mercruisers 7.4 carb, 7.4 MPI and 8.1MPI.

briman

 

[toyboat]

RWC or Closed Cooling? It makes a difference.

 

[flyboy]

Raw water cooled

 

[Quint4]

My 1990 220da 5.7 raw water cooled always ran 145 - 150. Have you changed the impeller ?

 

[Turtlesboat]

I run at 170 in mine.

 

[Salty Dog - LI]

I ran about 170 when I was raw water cooled, and 170 when I converted to closed cooling system. If you're dry docked on land, and pulling limited water through a garden hose, you could be 10-15 degrees higher.

You should be fine.

 

[flyboy]

The impellor, i was told, was changed at its last service which was done by the dealer i bought the boat from. I was just worried it may be something caused by me draining the water down for the winter. If the thermostat had stuck then the temperature would be much cooler and there seems to be a good flow of water from the leg. The boat was in the water for the winter, which was quite mild with us only having about 1 really cold week. Am i worrying over nothing?!

 

[comsnark]

If I recall correctly, you can get thermostats set for either 140F or 160F. Sounds like you have a 160F in your boat. Gauge and IR gun confirm operation in the 160F-170F range.

I don't know which is the correct thermostat for your boat -> but my boat has 5.7LX engines with Alpha drives and 160F thermostats.

 

[rondds]

i believe mercs are designed to run at 170. fwc and rwc. we'd need frank w to confirm or deny this, but if you're at 170, you're ok. also, you should be able to lay your hands on the risers and not get burned. if you're really concerned, get a laser temp thing and shoot readings at the thermostat housing.