Operating Temperature 56 Cad ?

[jeff1956]

Today, I just picked up my freshly re-cored radiator from the local shop.  I went in there expecting to be turned away because they have done this to me in the past, but to my surprise, a new owner had purchased the shop and was more than happy to re-core the radiator for me.  It cost 385.00, using one of my radiators with a good top tank out of a 55 hearse.  My question is this....what is the normal operating temperature of the 56 engines?  Mine with the new radiator is running at about 184 degrees( after idling in driveway for 20 minutes, then a 10 minute drive around town).  The temperature gauge is showing roughly halfway, however, it has a mind of it's own these days, and picks temps at random(sometimes 1/4, 1/2, 3/4, or pegged).  185 degree's does not sound like the car is running warm.  Sadly, I'm thinking my old radiator is still good and that the gauge has always been bad.  So, how does 185 degree's sound?

Jeff

Here's a pic of the new radiator fresh from the shop before install....my car is equipped with A/C and in order to remove the radiator you're supposed to remove the condenser.  Notice, I re-engineered this radiator to be bolted from behind so that removing the condenser is no longer necessary(addition of nuts on the front of the mounting surface). Not factory, but worked like a charm...

[Otto Skorzeny]

Yes, your gauge or sending unit might be faulty. How do you know the temperature is now185? Did you install an auxiliary gauge or something?

185 sounds a little low but I wouldn't complain. The test will come when you put in on the road. Will it stay the same or rise? How will the engine run at that temp?

I don't know exactly what temperature my car operates normally. I would guess it's somewhere around 200 degrees or so.

I had a 1972 Monte Carlo that ran at 220. I thought that was too high. When I installed a lower temp thermostat, the engine ran like crap. I put the old one back in and let 'er rip.

Don't worry about your radiator. It's 50 years old. It needed to be re-cored whether it was giving your car trouble or not. Sooner or later it would have started leaking or something so be glad you can cross it off the list. It looks like a good job, too.

[jeff1956]

i hooked up an auxilliary gauge to the radiator after running it in driveway and the short drive i took. the reading topped out at 185 on the aux gauge while reading halfway on the factory temp gauge.  it does have the 160 degree stat installed instead of the 180.....ive replaced the sender twice and both have performed this way.....im thinking a new or rebuilt gauge is in my near future...but i feel better knowing the radiator is new versus original...i gotta get her ready for next years grand national in kansas city.

jeff

[Otto Skorzeny]

When my car is operating normally the dashboard gauge just a hair below halfway. It is normal for the gauge to move up in traffic or idling to just below the high mark. It's not a sign that anything's wrong unless it's up there all the time.

[jeff1956]

thanks otto for your replies....im just trying to feel out the situation now that all the components have been replaced.  ive had this issue since buying the car, but going to school, ive not had the funds until now to really get things done. the second owner restored this car minus brightwork and its absolutely beautiful....but i couldnt figure out why she never got this rectified....i think ive got it on the run now though,  so ill be able to enjoy her more this summer   i think a drive in movie is in order soon.

jeff

[jeff1956]

i do have a shop manual and it doesnt list the operating temps in the cooling system section....it makes a brief mention to 170 degrees....but other than that i found nothing.....just wanted ya to know i did try to find it beforehand!  thanks again and have a great holiday!

[Otto Skorzeny]

170 seems unrealistically low but who knows?

[The Tassie Devil(le)]

G'day Jeff,

These Factory Gauges are only there to show the driver when the engine is cold, or hot.   They never were totally accurate in the "Run-of-the-mill" cars.   Drivers just wanted a simple needle to see, if ever they bothered to look at it.   Sports Cars and the like had the most accurate gauges as the manufacturers knew that the drivers of these cars wanted accurate readings.

Having said that, once you know where the needle is sitting, knowing the true temperature from the auxiliary gauge, you can see where the needle is pointing, and now you have a ballpark line to what the internal water temperature is like.

You did take the Temperature from the location of the original Sender Unit didn't you?  And, not the radiator itself?   Oh no, I remember you saying that you took it from the radiator.   As soon as you take the pressure out of the equation by removing the cap, the temperature will instantly increase.

Don't forget that for each 1 LB of pressure the cap has, the boiling point of the water will increase 2 Degrees.   Therefore, a 7 LB pressure cap will raise the actual boiling point of the water to 226 Degrees.  

The temperature of the water at the top of the Radiator is only going to show you the hottest point of the water inside the radiator, and it has escaped the confines of inside the engine itself and expanded slightly to start the cooling process in the Radiator.

Using a 185 degree Thermostat allows the hot water to begin its' return process to the Radiator when that temperature is reached as it will start to open.

The Radiator is just a heat transfer device that is designed to cool the hot water, and in the cooling process, it will ALWAYS be hottest at the top.

Start worrying when the hot water is at its' hottest when it is at the bottom of the Radiator, then you are in real strife.

Have a look at modern cars with Electric Cooling Fans and in most cases, the triggering switch is either at the bottom of the Radiator, or part way up.   If it was at the top, then the fan would be going ALL the time.   Fans aren't needed after the vehicle reaches a speed above 30 or 35 MPH as the air flowing through is sufficient to continue the heat transfer process.

Bruce.  

[jeff1956]

i did take the reading at the top of the radiator with the cap off.  i tested it again this afternoon and let the dash gauge peg full hot which took about 35-40 min idling in park...when i took the temp by the aux gauge it was between 195 and 200 at the filler neck.

jeff

[The Tassie Devil(le)]

What is the pressure reading of your Radiator Cap?

Bruce.

[jeff1956]

the cap is 16 psi which is the stock cap for ac equipped cars.

jeff

[The Tassie Devil(le)]

So, 16 PSI means that the Water isn't supposed to start boiling till an internal temperature of 244 Degrees F.

I don't think you have anything to worry about.

BUT, if you attempt to lift the Cap off when it is really hot, you WILL get scalded, burnt and really sorry for yourself because as soon as 244 Degree water hits Atmospheric Pressure, it immediately turns to Superheated Steam.   And, you definitely don't want to be on the receiving end of the "Gusher" that WILL come out.

Bruce.

[dan reed]

Jeff,

I have an aux. gauge mounted below the dash on my '56 (its an original 86,000 mile car) and it reads 185-190 under normal driving conditions. Maybe runs 190-195 on a really hot, humid summer day. I don't have air conditioning so I'm not always motivated to drive it when its 95 degrees and humid anyway. I too had the original radiator recored about 8-9 years ago.

Dan

[Mike Josephic CLC #3877]

Don't know for sure about '56 but the '55 shop manual says the radiator cap should
be at 12-15 pounds (max) and the standard thermostat starts to open at 163 degrees,
fully open at 188 degrees (F).  There was an alternate thermostat that fully opened
at 202 degrees (F) but I would not use that on a car of this vintage.

So, the 185 degrees you're seeing on the auxiliary gauge is right in line.

My temp gauge behaves pretty much like the others have descirbed (fully
rebuilt engine & cooling system).  Gauge shows just under 1/2 way up while crusing
but will creep to 3/4+ way up the scale if you are stuck in traffic.

Mike

[Otto Skorzeny]

tHAT'S WHAT THE '56  manual says too.  I'll check again but I think 16lbs is too high. I use a 13lb cap on my '56 with ac.

[jeff1956]

i have a 13 lb cap thats brand new....at the parts store it listed 13 lb cap for cars wo ac and 16 lb for cars w ac....i never checked the manual....ill look too and if its 13 lb ill switch it out.

jeff

[jeff1956]

the manual does say 12-15 lbs....ive installed the 13 lb cap i had for my prev 56 that was never used.  i guess i put too much faith in technology.  dont take their word bc the computer listing is wrong...ill retest tomorrow as its raining today.   thanks guys!

jeff

[jeff1956]

Lou,

That's a GREAT ad.  I've always thought that my car was running warm, with the old radiator, and a know a few times it was, but this was in 102 degree weather and extremely sticky outside...I haven't normally been running the a/c in my car either...though i do turn it on the keep it operational...but even hot arm pit sticky weather won't keep me away from my 56.  I'm only 25, so I never realized just how these gauges are supposed to operate....the one in my last 56 did not work at all, so this is my first bout with making sure everything is up to snuff.  Of course, my fleetwood is much more of a car than my sedan de ville could've ever thought about being..... which is why i want things to work right.  A friend, Alvin Arnold, not sure if anyone on this forum is familiar with him....had told me not to worry until it got past 3/4 on the gauge....he told me it was normal, but somehow I didn't really believe that.  I will start taking it a little easy in worrying if the car is running too warm.  My main concern is the fact that if I do overheat the gal and do damage, I don't have the funds to rebuild her, and she'd have to sit.  I enjoy driving her too much for that!  My mom bought her for me when i was 16, she's an old friend at this point and one of the only momentos left to me by my late mother.  Re-engineering the mounting on the radiator was actually my dad's idea....I didn't remove the condenser from the car when I removed my previous radiator...removing is easy, but I could not reinstall it without removing the condenser.  I know it'd dock points at a national show, but it was less work and believe me nobody has yet to notice that it's mounted reverse.  I think by next summer, I'll be ready to motor on over to the GN.

One side note:  Were these readings otto, with the ac running on your car?  or even to Lou...b/c I know your car has a/c as well....what is a normal baseline with the a/c running that I can check mine against....or should they stay the same?  Now that my cooling system is new....I may try to run my a/c more, but I have to find a blower motor speed switch....before I run it too much as my passenger side one is arcing out and heating up when the unit is turned on.

Jeff

Jeff

[jeff1956]

the most i could get out of her today....was between 180 and 185...idling in park for near an hour with the 13 lb cap installed...couldnt go for a drive bc with all the rain yesterday the road to the highway is flooded still.  im sure all is well now!  have a great memorial day everyone and thanks again!

jeff

[Otto Skorzeny]

On the highway the temp gauge stays right about the same with or without ac running. That's right about halfway. It creeps up in slow moving traffic a little sooner with the ac on but it doesn't seem to top out any higher.