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Topic: Maximum Coolant Temp (Read 994 times) previous topic - next topic

Maximum Coolant Temp

 I've been wondering about coolant temps since I have a nice shiny new radiator. Anyhow, the Cummins 8.3 manual indicates a maximum coolant temperature of 212 degrees F. Of course, that's the temp at which water boils. Since we run a 50/50 anti-freeze ratio, our boiling temperature is elevated. So... would this mean that the engine's maximum operating temperature is also elevated? Inquiring minds... Thanks.
jor
93 225
95 300
97 270
99 320

Re: Maximum Coolant Temp

Reply #1 –
Quote from: jor –
I've been wondering about coolant temps since I have a nice shiny new radiator. Anyhow, the Cummins 8.3 manual indicates a maximum coolant temperature of 212 degrees F. Of course, that's the temp at which water boils. Since we run a 50/50 anti-freeze ratio, our boiling temperature is elevated. So... would this mean that the engine's maximum operating temperature is also elevated? Inquiring minds... Thanks.
jor
The cooling system is also running under pressure which will increase the boiling point to a higher temperature (to approximately 257 F with a 15psi cap).  Cannot really address your primary question but I would not think it would be good to run hotter.
40ft 1997 U320

Re: Maximum Coolant Temp

Reply #2 –
Quote from: jor –
I've been wondering about coolant temps since I have a nice shiny new radiator. Anyhow, the Cummins 8.3 manual indicates a maximum coolant temperature of 212 degrees F. Of course, that's the temp at which water boils. Since we run a 50/50 anti-freeze ratio, our boiling temperature is elevated. So... would this mean that the engine's maximum operating temperature is also elevated? Inquiring minds... Thanks.
jor
No!

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Maximum Coolant Temp

Reply #3 –
Hey, Pierce. No need for such verbosity!  ;)
jor
93 225
95 300
97 270
99 320

Re: Maximum Coolant Temp

Reply #4 –
Mine hit 195 on San-Rafel pass in Utah this September. Didn't seem to be a problem. I was pulling a 5000 lb. cargo trailer with the old 8.3. 300hp. My speed was 37 at the top. My buddy has a 450hp and he was at 38 mph at the top. He is heavier but I was pleased.
1996 U295-36, Cummins 300hp, 8.3. Build number 4864. Vin number 1F97D536XTNO54271. Purchased October 31, 2019.

Re: Maximum Coolant Temp

Reply #5 –
Quote from: jor –
Hey, Pierce. No need for such verbosity!  ;)
jor
My apology as I was heading out to the grocery store so just typed no and hit send. Sorry again!!

The 50/50 mix raises the boiling point of the coolant so the hot spots in the cylinder head can't vaporize and create a really hot spot where the coolant is replaced by vapor,  which is not effective for cooling  and the metal temperature goes way up in a hurry. The engine specs are the same whether it's water or a antifreeze mix. At the design spec temperature, all parts of the engine are at the clearances, the dimensions, etc intended by the engineers so this is the optimum for good economy as well as long engine life. The higher boiling point of a 50/50 mix is good insurance for all seasons as it also cools better than a 100 percent anti freeze solution and at the same time drops the freezing point so the coldest winter won't cause the mixture to freeze, expand and then damage the block/head(s). An added benefit is the corrosion protection the additives in the coolant provide for the different materials found in the cooling system.

Water is the only liquid that expands when heated and also expands when frozen. So, frozen water (ice) is less dense than when not frozen.

OK, owe you a beer or two when we meet. :))

Pierce


Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Maximum Coolant Temp

Reply #6 –
When I had my Dynasty it would go up to 210 degrees and then stop there. I think that is when the fans went into high speed. It
never seemed to be a problem. That was and 8.3 engine.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Maximum Coolant Temp

Reply #7 –
Quote from: jor –
So... would this mean that the engine's maximum operating temperature is also elevated? Inquiring minds... Thanks.
jor
No still 212. Your just back to a fresh starting point. Very desirable. I'm sure we all have core envy
Scott