How hot can coolant get?

[demarpaint]

Did a search come up with all kinds of numbers, which triggered the question. Here's the facts and the numbers. it is about 95*F ambient tempurature today, in the sun I got a reading of 106*F on my porch.

I had a buddy replace my water pump in the 93 Aerostar, it was leaking and it was too hot for me to bother. I have a temp gauge/idiot light which has a band spelling the word normal. I would run between the O and R in the word NORMAL, with the old pump before it went bad. I'm now around the M and A. I took out the digital thermometer and aimed it at the thermostat housing and get a reading of 215*F after about 30 minutes of mixed driving. I have no idea what it read before.

This is after flushing the radiator and replacing the thermostat with a 195*F thermostat. Prior to flush and replacement and after the pump installation I was getting the reading between the M and A, so the flush and thermostat didn't change anything.


I did read a v6 can get as hot as 240*F, seems high. I guess I could get a temp reading from my Jeep and E-150 and compare. I thought I'd ask you guys.


Many thanks again!

 

[StevieC]

Sounds like your previous thermostat was a bit weak and opened up a little earlier.

195F Thermostats don't all open at 195, there is some play in either direction by a few degrees because they aren't precise.

What this does prove is that your temperature sensor is working well!

You are in a good range of "NORMAL" so don't worry about it.

If you want to do anything put some Water-Wetter in the coolant mixture.

In my all aluminum engine the water temperature gets no higher than 212F as per my scan-gauge before the cooling fan kicks onto the highest speed to bring it back down. I have a 195F thermostat.

 

[eljefino]

Often the back of the coolant jug has a chart, assuming a working 15 psi cap.

 

[mechanicx]

I think 215F at the T-stat outlet after driving on a hot day is OK and probably normal. I would not like to see coolant temperatures much higher. Maybe your temperature sensor is reading more accurate after the flush? It could be possible that you have too high concentration of anti-freeze to water.

 

[demarpaint]

Thanks Stevie. So 215*F is OK? At what temp does a person worry? It will be running for an hour or more in traffic, not that I want it to, but rush hour drive home puts my wife right smack into that mess. I'll take a reading again during the week.

Water Wetter will work with Anti-Freeze?

 

[demarpaint]

Good point about the cap. The cap is a 7 lb cap. I know, I know, but in this old engine radiator combo I don't like too much pressure. I had repaired a small leak a few years back in the radiator, and replacing the radiator is not in the budget, so I lowered the cap pressure instead. It' been that way for about 6-8 years now. Old school.

I had the AF to water mix correct. I have a feeling my buddy might have gone too much AF when he changed to pump. When it cools down I'll take a reading and might have to up the distilled water a bit.

 

[StevieC]

Originally Posted By: demarpaint
Thanks Stevie. So 215*F is OK? At what temp does a person worry? It will be running for an hour or more in traffic, not that I want it to, but rush hour drive home puts my wife right smack into that mess. I'll take a reading again during the week.

Water Wetter will work with Anti-Freeze?


Because my engine is all aluminum they have to manage the heat better and keep the temps lower. I think that is why my cooling fan enters "OH MY GOD" fast mode and rapidly tries to bring the temperature back to the 188-190 it normally is.

Your engine having cast-iron is fine with higher temperatures than mine but I wouldn't be concerned as long as it was less than 230F

I haven't used Water-Wetter myself but OVERK1LL swears by the stuff and he is someone I trust. Check it out. (Not sure if you mix with anti-freeze)

 

[Chris142]

Originally Posted By: demarpaint
At what temp does a person worry?
240 with your cast iron block and head. Anything over 240 and you need to get it into the wind.I came up Cajon pass yesterday in 105 degree heat with my AC on and 80 mph. Jeep was sitting right on 225 on the steep part, fan clutch was roaring.

Newer Cads have a 2 speed engine cooling fan. Low comes on @ 226 and high @ 235. The Boxy Jeep Cherokees run 230 all day long. The radiator in them is very marginal, Jeep changed the sender to show "normal" which is 210 when the engine is between 190 and 230 to prevent people from panicking.

With your 7lb cap you will boil at about 235 so in your case start watching it @ 230.

 

[renos09ram]

In my Dodge Ram it has a 192 deg thermostat and the coolant sits at 194 and the oil temps are at 197, this is with outside temps of 98 degrees and a/c. I changed the thermostat from the original (203 degree)to the 192 degree.

 

[J. A. Rizzo]

I don't think you need to worry, but the pressure cap is pretty low at 7 lb. and those things do wear out over time. I would up it to at least 10-12 lb., skip the water wetter and make sure the mix is 50/50. Water cools better than antifreeze, but in NY you'll see some cold temps so I wouldn't drop the antifreeze percentage lower than 50. Maybe hose off the radiator to clean off some of the road grime and bugs for a little better heat transfer. I usually mix up dish soap and hot water and pour that on the radiator and condenser, let it soak a few minutes, then hose it off really well with the Jet setting on the nozzle.

 

[demarpaint]

According to my tester my mix is about 45/55 55 being water, I'll tweak it for winter. The only reason it is off is probably because my buddy used a 50/50 premix AF when he changed the water pump. I was topping off with water while the pump was leaking.

The condenser and radiator are clean, I stay on top of that. I could increase pressure via the cap but I'm afraid I might trigger a leak. The car is a beater and I'd rather spend money elsewhere if you know what I mean. I don't abuse it, it is well maintained but it is a point where if it goes I'd rather take the money I'd spend on a radiator, shocks, springs, etc and put it toward a newer vehicle.

 

[mechtech2]

demar - You did not measure coolant temperature. You measured a part that has hot coolant in it and was ALSO heated by being connected to a very hot engine. As an extreme, measure the cyl head temperature - it also has coolant in it!

Coolant temp gauges stick in the middle for about a 30 degree range. They don't want to alarm customers with wavering needles!

You may have a coolant sensor for the gauge, and also for the computer. You can measure the resistance at operating temp to see what is really going on there. Get a chart/specs for your car, and measure the right sensor.

 

[hooligan24]

I have done 35 minute sessions on a roadcourse with the coolant temp sitting around 230-235 with the high speed fans going. It was 102 degrees out that day. At the time I had a 180 tstat and water wetter in the 50/50 mix of Mopar HOAT coolant. I think the reason of the high coolant temps was due to having a coolant/oil heat exchanger, and the oil temps approaching 280f

I have read(could be rumors) that with an 18psi radiator cap and a 50/50 mix of coolant to water, it should have a boiling point in the 240's

 

[hooligan24]

just found this:

Car Maintenance Videos

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Fluid
Cars operate in a wide variety of temperatures, from well below freezing to well over 100 F (38 C). So whatever fluid is used to cool the engine has to have a very low freezing point, a high boiling point, and it has to have the capacity to hold a lot of heat.

Water is one of the most effective fluids for holding heat, but water freezes at too high a temperature to be used in car engines. The fluid that most cars use is a mixture of water and ethylene glycol (C2H6O2), also known as antifreeze. By adding ethylene glycol to water, the boiling and freezing points are improved significantly.


-FREEZING POINT-
-pure water 0C / 32F
-50/50 C2H6O2/Water -37C / -35F
-70/30 C2H6O2/Water -55C / -67F

-BOILING POINT-
-pure water 100C / 212F
-50/50 C2H602/Water 106C / 223F
-70/30 C2H602/Water 113C / 235F




The temperature of the coolant can sometimes reach 250 to 275 F (121 to 135 C). Even with ethylene glycol added, these temperatures would boil the coolant, so something additional must be done to raise its boiling point.

The cooling system uses pressure to further raise the boiling point of the coolant. Just as the boiling temperature of water is higher in a pressure cooker, the boiling temperature of coolant is higher if you pressurize the system. Most cars have a pressure limit of 14 to 15 pounds per square inch (psi), which raises the boiling point another 45 F (25 C) so the coolant can withstand the high temperatures.

Antifreeze also contains additives to resist corrosion.

 

[demarpaint]

Originally Posted By: mechtech2
demar - You did not measure coolant temperature. You measured a part that has hot coolant in it and was ALSO heated by being connected to a very hot engine. As an extreme, measure the cyl head temperature - it also has coolant in it!

Coolant temp gauges stick in the middle for about a 30 degree range. They don't want to alarm customers with wavering needles!

You may have a coolant sensor for the gauge, and also for the computer. You can measure the resistance at operating temp to see what is really going on there. Get a chart/specs for your car, and measure the right sensor.


I measured at the thermostat housing, while the engine was running after a 30 minute drive. I understand what you're saying. So in reality it might have been cooler than my reading, is that what you are saying? I figured the thermostat was open and coolant was going through it. I can try aiming the lazer at other points of the engine as well. Thanks for bringing that up!

What started this whole thing was the engine at least by my idiot gauge is running hotter with the new water pump. Which in turn sparked me to flush the radiator and change the T-Stat.

 

[Chris142]

Originally Posted By: hooligan24


I have read(could be rumors) that with an 18psi radiator cap and a 50/50 mix of coolant to water, it should have a boiling point in the 240's
every 1 psi raises the boiling point 3 degrees.

So lets say that a system has only water in it and the car is @ sea level. If you took the radiator cap off it would boil @ 212f. If you added 18psi to it with a 18psi radiator cap you would raise the boiling point 54 degrees.

212+54=266 w/o coolant. Adding coolant will raise the boiling point slightly higher. I'm not sure how much higher.

This is why we recomend a 13psi radiator cap @ my shop. A 13psi cap will raise the boiling point 39 degrees to 251...Probly closer to 260 with coolant added. Not too many engines get that hot so I see no reason to put a bunch of pressure on the cooling system.

 

[mechtech2]

Yes - the coolant was almost certainly cooler than your external reading of a metal part.
But really, see what you get off of the actual sensor - the resistance reading compared to what it should be at whatever temps.

 

[demarpaint]

Thanks I'll have to read up on that, get the specs and figure it out.

 

[mechtech2]

http://fordfuelinjection.com/?p=28
You probably have this.