What's a safe engine temp for non-pressurized cooling system?

[12905]

Pat: I believe the car was delivered with a 160 deg. thermostat, but I also think a 180 deg is better for the engine as, generally speaking, the hotter an engine runs without boiling its coolant the quicker the contaminants are evaporated and the cleaner the oil stays - contributes to reduced bore wear also. If your cooling system is in good shape and you have followed the advice given previously you can install a 180 thermostat and the engine will run at that temperature under all but extreme ambient temperatures. For coolant use a 50/50 mix and replace it every three years maximum; it's actually a better coolant than straight water. In fact, I don't think there is ever a good case for using plain water as a coolant as antifreeze contains rust and sludge inhibitors.

I have a 36 and I run a 180 thermostat and idling/crawling in traffic on hot summer days (up to about 90 deg. F) engine has never overheated.

[36 Ply]

I've gotten some good advice from the replies.

I don't know if the temp gauge is accurate.

I removed the radiator 9 years ago and had it boiled out.

I replaced the water pump last fall.

I've never looked in the water jacket, pulled the core plugs, or checked the water distributor tube.

I would still like to hear some opinions on what is safe for a flathead 6 with a non-pressurized cooling system.

I've seen opinions on other forums, such as "100% water will make an engine run cooler than a 50/50 water/antifreeze mix."

If you are using a 180 degree thermostat for example, what happens on a hot summer day in hilly country?? If your thermostat doesn't open until 180 degrees, does the temperature have to stay at 180 to be safe?

So, what IS safe?? ? ?180?? ? ? 190?? ? 195?? ?Notwithstanding the condition of my cooling system,? what's a safe operating temperature?? I would think that the answer would be the same for a brand new engine or a refugee from the boneyard.

Regards,

Pat O'Connor

[brucepine]

For a quick-easy check of your temp gauge, I have found my wife's turkey/roast push in oven thermometer will give you a ballpark reading.  Place it in the radiator fill port and don't tell your wife.  Ours is calibrated from 120 - 190 in 10 degree increments.

[John Hendricks]

I have gotten new thermostats from Roberts in MA, and I think they are in the 160-180 range.  Your temps sound a little high.  Have u flushed things out recently.  It might be time to take the radiator to the shop for a thourogh cleaning.  The old system was not designed for modern antifreeze, as I understand, but if everything is clean, it should be OK.  I use a 50 50 mix in my 32, 40 and 49 w/o problems.  Checking the gauge might be necessary but it is a somewhat arduous task getting the thermostat bulb out of the block intact.  I have checked mine in the kitchen with a thermometer and boiling water

[TodFitch]

Running at 190 to 200 does seem high. . .

I use 50/50 mix in my 1933. I also have a 160 degree thermostat in there. With the new radiator core and the cooling jacket cleaned out I seldom see more that 140 degrees on my calibrated dash gauge. Mine runs too cool which means I have to worry more about water and acid build up in the crankcase. I ought to put in a 180 thermostat some time. . . In any case, you can be running cooler than you are.

You don't say what condition things are in. Which brings up a number of questions:

1. Is the temperature gauge accurate?
2. Do you know the condition of the radiator?
3. Do you know the condition of the water jacket on the engine?
4. Has the water distribution tube been inspected or replaced?

I guess I would start with back flushing the radiator and the block. When you have the hoses off and thermostat off for that you can perform the radiator flow test recommended in the manual.

If that doesn't work then the next step would be to pull the freeze/welch/core plugs on the block and using a coat hanger (or equivalent) loosen and remove the build up in the block.

Next step after that would be to pull the water distribution tube.

Heck, it could be as easy as a miscalibrated temperature gauge or a incorrect thermostat. But in any case you ought to be able to get the engine to run cooler.

[36 Ply]

Hi all,

I'd be interested to have some knowledgeable members weigh in on a safe engine temp for a non-pressurized cooling system on a flathead 6 engine (1936 specifically).

It's a bit unnerving when your temp gauge reads 190-200 degrees and the highest number on the gauge is 212.

How about it? Any tricks to keep things cool?

What's the best temp to keep the engine happy but not overheated?

What's best for cooling in the summer? 50/50 water & antifreeze?? ? Straight water?? ? ?Or ????

Thanks for any and all input.

Pat O'Connor