Operating Temperature on your Flatties

[Cpt.Fred]

hi all!

i have a question regarding the TEMP gauge in our cars:

the first 3 trips the needle reached the middle of the scale and stayed there,

yesterday however it rose 1 1/2 points higher, and i don't really know why, nor do i know if that's already too much...?

i opened the hood and checked, but i didn't really think it felt too hot.

there where small water stains under the filler neck of the radiator, though.

also i noted a small hissing noise from time to time coming from the engine compartment. any ideas?

how high does your TEMP needle rise?

best,

fred

[greg g]

Without knowing how accurate the gauge is. its reading is kind of false information till you know. Get a known accurate thremometer ad put it in the coolant. The top of the radiator is close to the hottest temp the coolant will be as it is just coming out of the engine. Once you know how hot hot is, the you can have an informed conversation of the results.

Mine runs 165 to 170 in normal operation. When its hot, and sitting in traffic, it will run up to 190. Never seen it above that except when we sat for 40 minutes in 85 degree direct sun waiting for customs at the US Canada border.

Climbing hill in hot weather it runs up to 180 give or take a couple degrees.

I have checked my gauge against a calibrated cookinng thermometer.

[TodFitch]

I have a 160F (71C) thermostat in my 1933. Generally the engine shows 150F (65C) on the dash indicator. On a long upgrade, with a full load (two adults, large dog and luggage for a trip), on a hot day (100F, 37C) I have seen the dash indicator reach 180F (82C).

I have calibrated the dash indicator on my 1933 and it is actually marked in degrees so I think those coolant temperatures are reasonably correct. I really ought to put a 180F thermostat in the car and maybe I will the next time I break the seal on the cooling system.

[Cpt.Fred]

ok, then i'll go buy a cooking thermometer of some kind and make some tests during the next trips.

mine would be about 165-175F on the gauge, let's see how much that really is.

i was only worried because it didn't rise that high on the first runs...

thanks!

todfitch: now where do i find a large dog for my test runs?

[TodFitch]

[quote=Cpt.Fred;194117todfitch: now where do i find a large dog for my test runs?

Our last couple of dogs were adopted from the local animal shelter. Lady, who passed away last spring, weighed about 80 pounds. I don't think you would get the same loading effect in your car with a smaller breed.

[BobT-47P15]

A hissing noise in relation to heat could mean a pinhole leak in the

radiator or one of the hoses when coolant is hot.

Are all the hoses new, clamps tight? How aboout the hoses to the

heater - good condition? Just some guesses.

[Cpt.Fred]

the hoses are used ones, but seem to be in fine condition, so i didn't change them. i haven't lost any coolant so far, or at least very very little.

it's nearly like the noise a large truck makes when it blows off the pneumatic pressure from the air brakes, only very faint.

i guess i'll just run the car a few more miles and then i'll tell you what i found:rolleyes:

my girlfriend likes the hissing, she says it makes the car even more boatlike then it is already

first thing tomorrow is borrowing a thermometer from my friend's garage...

[P-12 Tommy]

hi all!

i have a question regarding the TEMP gauge in our cars:

the first 3 trips the needle reached the middle of the scale and stayed there,

yesterday however it rose 1 1/2 points higher, and i don't really know why, nor do i know if that's already too much...?

i opened the hood and checked, but i didn't really think it felt too hot.

there where small water stains under the filler neck of the radiator, though.

also i noted a small hissing noise from time to time coming from the engine compartment. any ideas?

how high does your TEMP needle rise?

best,

fred

Vacuum leak somewhere?

Tom

[LAKOTA169]

On my '37 coupe, the top line reads 212. when my engine is warmed up, the needle is just below the blank line under the 212 line. I have a 180 thermostat. When I've been stuck in stop and go traffic in 90+ temps, it will go to the line just under the 212. As soon as I start moving steady, it will drop back down.

[DutchEdwin]

Fred,

Get a thermocouple temp meter. Then you only have a wire to measure with. Instant temperature reading on surfaces and in fluids.

Edwin

[Cpt.Fred]

a friend just mailed me he had a thermometer for me to borrow.

i'm going to fetch it after work and i'm planning to do a night driving test and adjust lamps and everything (already switched back to sealed beams;)),

that's a good occasion to test the temp as well...

[Cpt.Fred]

alright, did some testing yesterday. a friend had one of these wire thingies and we measured the water temperature after an hour of stop and go city traffic.

the temp gauge is surprisingly accurate, 170F on the gauge and the thermometer reads 168F.

the temp goes up to 180F-185F and stays there, which should be fine i guess?

maybe i was just a little overcautious, because everythings new to me with the car...

[chopt50wgn]

Just alittle FYI for all.............most sending units for the temp gauge is near or close the outlet water neck to the radiator. So keeping that in mind, if everything in the cooling system is doing it's job, pump, fan and radiator, then the thing one has to remember is the coolant is being gauged at it's hottest point right as it exits the motor and goes into the radiator.

If the radiator is up to par, the temp drop across it should be 15-20 so the coolant going back to the motor is cooler and then the cycle goes on.

[greg g]

Now you know the rest of the story, and have some piece of mind. Your temperature range is right where it should be with what is likely a 180 degree thermostat. And you now know that your gauge is accurate. When it gets over 190 for extended periods then you need to pay attention. Also make sure you are not over filling the radiator. As long as the coolant covers the openings to the cooling core you are good to go. The top of the radiator provides room for expasion. Most folks will notice that a full radiator will purge coolant after a run when the engine is shut down. This is the system getting rid of the fluid it doesn't need. A lot of folks will then refill it and think something is wrong when it purges again.

[Cpt.Fred]

had the same thing on my old 60s opel rekord, so i know how to handle that, but is it right that the cooling system on our old mopars is pressure free?

in my opel cih motor (and nearly all other motors i know, except the 32 fords of some friends here) the system builds up pressure to delay the coolants boiling point... 170F in an opel engine would be to low actually.

i'm confused, but only a little:)

tomorrow i ask stupid questions about my next problem on the car.

sleep well, all of you!

i'm shutting down here...

best,

fred

[Niel Hoback]

Yes, its true, our P-15's have a zero pressure cooling system. You'll find a tube running from the top of the radiator tank down the side and open to the atmosphere. That way, no matter what kind of cap you may put on it, there will be no pressure build-up.

[Granger Perry]

How hot can you get one of these motor without hurting something?

[Cpt.Fred]

at least 212°F, i'd say.

if the system operates without pressure it will reach the coolants

boiling point here and start blowing water out of the system very fast.

if you stop at this point and let it cool down nothing will be damaged.

the fact that they didn't use a pressurized system to move the

boiling point up the scale shows that it shouldn't get much hotter

than that.

someone correct me if i'm wrong...

after cleaning the engine and radiator with acid it now stays between 170°F and 190°F at all conditions, even in midsummer traffic jams.

[JoelOkie]

at least 212°F, ... it will .... start blowing water out of the system very fast.

someone correct me if i'm wrong....

You ain't wrong, Fred, after 212 is where the scheisse hits the lyfterkupplung But if you turn the heater on and get moving again pretty quick it might go back down until you can get where you need to go, if not, stop and start looking for water. Joel Edited August 8, 2011 by JoelOkie
spelling

[greg g]

The problem with boiling water is that the bubbles loose contact with the metal, there fore if can not absorb more heat, so even though the gauge will read 212 or a bit higher with a 50/50 mix, the engine actually is getting hotter. So once you start boiling, its a good idea to shut thing down, or at least pull over an let it run at idle. As when you shu everything, down, stuff stops circulating and temps can and do actually go up, for a while before they actually start to cool.

If you notice when you shut your car off, the mechanical gauge will actually pick up 10 to 15 or more degrees, before it starts cooling. If I shut mine down at 170, it will go up to over 190 before it starts coming down. the heat has to go somewhere. so it keeps going into the coolant after shut down. Same thing with modern cars but you don't notive it as the gauge shuts down with the ignition off.

But most of you have probably noticed that cars with electric fans, will fire up the fan after a couple minutes of being shut down. That great but it is only cooling the stuff inthe radiator...

[meadowbrook]

As far as the temp scale, my Meadowbrook's gauge has 4 markings, the COLD one, a 2nd, a 3rd and a 4th one tha says HOT. My car normally runs right on the 3rd line and gets there pretty fast after startup. In heavy traffic, it may rub slightly beyond that 3rd line, but stil mostly over it. I will measure the actual coolant temp to see what that means. I have a 180 deg t-stat and I believe my cooling system runs at 4 psi.