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Add on Temperature Gauge

Started by Jvteach07, August 16, 2020, 03:18:43 PM

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Jvteach07

I have a 1970 Deville. It seems to be running a little hot but it is hard to actually tell as there is no temperature gauge just a dummy light. The coolant level in the overflow when it seems hot goes ABOVE the full level, but when it drops down to the normal level the temperature seems fine. Is there an easy way to add an actual temperature gauge? Or a reason why the overflow tank level goes above the full line? New Aluminum radiator, hoses and thermostat installed a few months ago
Joe Tortora
1970 Cadillac Devill Convertible

chrisntam

Easiest way to tell if it's hot is to get a hand held laser temperature gun. They run about $25, IIRC.

I have a gauge on mine, in the heat of Texas summers, at idle in traffic w/ the a/c on it will creep to 210 to 220.   Running down the road w/ plenty of airflow, temp is around 190.  I have a 180 stat in mine.

These engines run hot, the folks on the boards will tell you that.

Can't help with the overflow part of the question.  Was it boiling over?  Out the overflow?
1970 Deville Convertible 
Dallas, Texas

35-709

They do run hot and were designed to do so. 
Did they install the correct thermostat when you had the radiator replaced?  Many will fit, only 2 are correct, see pics below.  Your engine came new from the factory with a 195* thermostat, an optional one available at parts stores is a 185* --- not a 180 or 160, there is no correct 180 or 160 degree thermostat for your engine.  Don't know if Cadillac ever offered a 185* in the correct design, but you could buy them on the aftermarket. 
Your temp. light will tell you if your engine is truly overheating before any damage is done.  I had a gauge on one of my my 472s for a short time and could see 235* on a hot day in FLA but did not "overheat".  I took the dumb thing out, too distracting.  If the coolant in your overflow bottle is not boiling and overflowing you are OK.
A recommended 50/50 antifreeze/water mix will boil at about 235*, with a 15 pound pressure cap it will boil at about 257*.

Pic. 1  A correct thermostat, designed for the 472/500
Pic. 2  A thermostat that will fit and is used in lesser cars, but is not designed for the Cadillac 472/500, there is a difference
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

chrisntam

#3
Rock auto lists 195s & 180s.  What's 5 degrees among friends?   ;)    Motorad lists a 160, which I think is too cool.   I agree, the temp gauge is somewhat distracting.  When I ran small block chevys, they ran 160 / 180 all day no matter where you were.
1970 Deville Convertible 
Dallas, Texas

35-709

OK, new stuff comes up all the time.  Would never run a 160 in a 472/500.
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold - but still in the family
1950 Jaguar Mark V Saloon resto-mod - Sold
1942 Cadillac 6269 - Sold
1968 Pontiac Bonneville Convertible - Sold
1950 Packard 2dr. Club Sedan
1935 Glenn Pray - Auburn Boattail Speedster, Gen. 2

ifixmycarmyself

I vote for no termostat, at all.
In my experience (-69 472, single exhaust) you might as well run without a termostat and it still running hot. Those engines are running too hot. A rinsed/cleaned radiator, double exhaust, blocked fan clutch and smaller water pump pulley takes down temperature but it will still run hot. That you can se when you open a valve cover and find all the burnt oil gunc in there (and it's not only there, it's everywhere in the engine and designers didn't have to think about that). Never heard of a 472 or 500 not reaching working temp so who needs a termostat? Unless you drive in winter time freezing cold :)

bcroe

I always put in a bigger radiator than original, and a compact 1.5 inch
gas bulb temp gauge, easy to read with a needle that sweeps 270 deg. 

That gauge will tell you how things are going all the time, and give a
lot of warning before overheating.  AND, help you manage a cool down. 

Bruce Roe

"Cadillac Kid" Greg Surfas 15364

Without a thermostat or restrictor plate in the water outlet ALL ENGINES WILL RUN HOT.  Flow through the motor is increased to the point of cavitation in multiple locations.  That said Cadillac 472/500s will run even hotter because the secondary purpose of the Cadillac thermostat is to close off the warm up assisting bypass so some of the coolant just recirculates without going through the radiator.
FWIW in my (grandpa's) hot rod 511 inch motor I have the bypass blocked and am using a high capacity 165 degree thermostat.  The motor of course ignores the 165 degrees, and once it is warmed up it typically runs 110 to 120 degrees above ambient temperature at cruise.  They reason for a lot of accumulated "gunk" is typically a motor that runs too cool or never warms up, not one that runs hot.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

ifixmycarmyself

That explains why we se all these overheating Cadillacs (and other big engine cars) at car meetings and crusings. They just got the wrong thermostats that is not blocking the bypass hole directly under the thermostat. Aluminium radiators and double electric fans are a  big business but a correct thermostat will cure the problem. I'll have to remember this when the problem shows up the next time. And I always thought the oil gunk was because of a too hot engine because all this gunk is mostly concentrated in the warmest place close to exhaust ports under the valve cover and not because it's to cold but we always learn new things :) thanks for info Greg.

Jvteach07

Quote from: bcroe on August 17, 2020, 10:52:18 AM
I always put in a bigger radiator than original, and a compact 1.5 inch
gas bulb temp gauge, easy to read with a needle that sweeps 270 deg. 

That gauge will tell you how things are going all the time, and give a
lot of warning before overheating.  AND, help you manage a cool down. 

Bruce Roe

Where can I get a compact 1.5 inch gas bulb temp gauge?
Joe Tortora
1970 Cadillac Devill Convertible

bcroe

Quote from: Jvteach07
Where can I get a compact 1.5 inch gas bulb temp gauge? 

Try this at Evil bay or JEG*, and others.
Auto Meter 2352 Autogage Water Temperature Gauge

These are so small,  I find a spot in the dash, not hang them below. 
Bruce Roe

Jvteach07

Thats great, Where does the sender get installed for the gage?
Thank you again
Joe Tortora
1970 Cadillac Devill Convertible

bcroe

Quote from: Jvteach07
Thats great, Where does the sender get installed for the gage?
Thank you again.

Its a gas bulb gauge, the only wiring is for the light at night. 
It is one assembly, a tube runs all the way forward to have the
end screwed into the engine.  Could complicate installation, it
works on all my cars.  Bruce Roe

Jvteach07

Here is what I’m talking about. This level MOST of the time is always on full but occasionally will raise above full .
Joe Tortora
1970 Cadillac Devill Convertible

chrisntam

The coolant should be between the lines when hot.  If the coolant is above the line when hot, there may be too much coolant in the system.  Where is the coolant when the engine is cool?

On the sender location, I removed the ported vacuum switch (and associated vacuum lines) from the front of the engine and put it there.  I left the factory temp sender in it's factory location.
1970 Deville Convertible 
Dallas, Texas

colinlikens

I keep thinking that there should be a supplemental gauge system that wirelessly sends the data to your smartphone rather than requiring the addition of unattractive add-on gauges.

A few minutes of searching online produced no results however.

Does anyone know of such a device/system?

Thanks.
1973 Eldorado Convertible
2008 DTS
1978 Buick Estate Wagon

"Cadillac Kid" Greg Surfas 15364

Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

Jvteach07

When cold the level is at the full line.
Joe Tortora
1970 Cadillac Devill Convertible

"Cadillac Kid" Greg Surfas 15364

Joe,
You have too much coolant in the system.  you can either remove some of the coolant from the overflow tank then warm up the engine and replace coolant as necessary to bring the level up to the full line.  CHECK THE COOLANT LEVEL WHILE HOT.
Greg Surfas
Cadillac Kid-Greg Surfas
Director Modified Chapter CLC
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-

cadillacmike68

Quote from: chrisntam on August 16, 2020, 08:45:57 PM
Rock auto lists 195s & 180s.  What's 5 degrees among friends?   ;)    Motorad lists a 160, which I think is too cool.   I agree, the temp gauge is somewhat distracting.  When I ran small block chevys, they ran 160 / 180 all day no matter where you were.

I use the rockauto or amazon sourced ACDelco 180deg 12T18D with the proper extension to block off the bypass when it opens up. Down here I need every bit of help I can get.

Was stuck on a 2 hour DOT imposed jam on the frankenstein bridge last week, 8 mile long bridge so no chance to get off, while the temp gauge slowly creeped up on me.  >:D
Regards,
"Cadillac" Mike