Checking radiator for overheating problem with 1956 Thunderbird

[cokefirst]

I have owned 7 little thunderbirds and it has been my experience that the normal operating temperature on the factory gauge is at the end of the red line closest to hot. Purchase an infrared temperature checker (you can buy and inexpensive one from Harbor Freight) and check the actual operating temperature.
With a 7 # cap at sea level, the boiling point of water is about 228 degrees. So if your temperature at the top of the radiator is less than that (say 218 degrees) you are good. The 180 thermostat is supposed to keep the coolant at the minimum of 180 degrees. Once it reaches that temperature, the thermostat opens and should be fully open at 200 degrees. Remember that what we call a temperature gauge is really an indicator since it is not calibrated with actual numbers.

 

[KULTULZ]

What happens if and when the coolant temp exceeds the boiling point, the cap (if operating properly and the correct pressure rating) will open and expel coolant to somewhat normalize internal system pressure. The trouble is as the coolant cools, that open cap will draw outside air and that is where your air pockets and aerated coolant comes into play.

It needs a recovery system.

EDIT -

The above is also true when the engine is shutdown and heat soak heats the coolant to a point where it forces the cap pressure release to open and burps coolant all over you nice cobblestone driveway. As the engine cools, the coolant contracts drawing outside air into the system before the cap relief fully closes. You then have air pockets in the cooling system which may cause further overheating problem(s).

 

[Ford blue blood]

I live by a simple rule....If it ain't losing water it ain't over heating....engine will be fine as long as it has coolant in it.

Got caught in traffic in Memphis on a 100 plus day, temp went up to 220, turned the air off much to the wifes ire, finally got back on the road and all was well. That was some 60K miles ago on that ol 351C in my 36.

 

[blucar]

I generally run aftermarket improved fan blades on my vintage vehicles, have a couple old cars with AC, electric fan with shroud or a thermal clutch type.
Many years ago I had a '65 Chevy C20 camper special, V/8 AT with a large RV camper on it. The first two years I had THE '65 I had nothing but trouble with it running hot, gauge almost maxed out.
Tried everything to cool the engine down, larger radiator, HD fan assembly, larger trans cooler coolant recovery system. I finally put a mechanical temp gauge on the engine, leaving the stock gauge in place. The mechanical gauge never got above 200/215, 15 lb cap and 50/50 coolant put the boiling point to about 250, the engine did not boil over and the coolant recovery system did it's job.
Going over the Donner Pass in August 1970 towards Reno the trans over-heated and burped fluid from the fill tube onto a hot manifold, lots of smoke, thought the engine was on fire, then noted the smoke was intermediate, just short puffs, pulled over as soon as I could, leaving the engine running I grabbed my fire extinguisher and slowly opened the hood. Seeing what the problem was I let the engine idle for awhile to lower the temp then continued on to Reno.
I went to the GMC agency in Reno to have the truck checked over, other than the trans fluid being a little low everything seemed to be fine. Myself and a mechanic took the truck for a test drive, he suggested that I run the trans, a TH400 a little low on the dip stick to avoid oil boil over from over heating.
The mechanic then asked me what year was the truck, I told him '65, he replied that GM had a lot of trouble with the '65 C10-20's running hot, there was a factory recall on the trucks, their shop saw a lot of them coming out of California with reputed overheating problems. The problem was a faulty gauge, the fix was a factory supplied resister in the wire to the gauge.
Moral to the story, it is very common to make a minor issue into a big deal, a mole hill becomes a mountain.

 

[zuburg]

It was over 240 and rising. At that point it was bubbling coolant at weak hose points. When I checked the bypass hose, I notice the nipple on the thermostat housing was corroded and Deformed so I bought a new housing and bypass nipple while I was at it. I just finished putting it all back together earlier today. I did use the technique you described of putting the bypass nipple in the hose, connecting the hose to the housing first, then just dropping the bypass nipple in place. Went nice and smooth for a change.

I plan to add coolant tomorrow and doing another pressure check to make sure everthing is tight. Then a test drive on a 94 degree day.

 

[dmsfrr]

It was over 240 and rising.....

Can you see coolant moving thru the radiator?
Remove the radiator cap when the engine is cool or at least not too hot. Then let it run (with the garage door open) until the engine gets up to operating temperature and look into the top of the radiator. You should be able to see the coolant circulating.

 

[zuburg]

I have tried that to confirm it is circulating, but I have heard it won’t circulate if under 800 RPM. I wonder if that is why I can’t tell if it is circulating. Next time I will get my wife or a friend to help by increasing the RPM. I have taken temperatures of the thermostat housing, upper/lower radiator hose and 3 places on the radiator fins (top, middle and lower). The temps on the radiator fins progressively got cooler from top to bottom. I thought that indicated it was circulating?

 

[KULTULZ]

I have tried that to confirm it is circulating, but I have heard it won’t circulate if under 800 RPM. I wonder if that is why I can’t tell if it is circulating. Next time I will get my wife or a friend to help by increasing the RPM. I have taken temperatures of the thermostat housing, upper/lower radiator hose and 3 places on the radiator fins (top, middle and lower).

If you look into the upper tank with the cap off (be careful here) and the thermostat has opened, if you don't see coolant movement, you need to increase the speed of the water pump, i.e. a smaller dia water pump pulley. Just reach over and operate the throttle linkage by hand. If you see flow at a higher RPM, you will likely need a smaller WP pulley. You have a 4-blade fan?

The temps on the radiator fins progressively got cooler from top to bottom. I thought that indicated it was circulating?

That indicates it is cooling. It does not indicate fluid flow rate which is going to dictate rate of cooling..

This is one problem with BIRDS, the other being a bad pump and/or WP spacer (8A510) volute and/or timing cover volute.

How long has it been since a complete cooling system service, hose/thermostat and coolant replacement?

1st EDIT -

Here is a basic tutorial - https://www.ctci.org/gilsgarage/1955-56-57-thunderbird-overheating/

Your IGN SYS is LOAD-O-MATIC and if the ignition advance is inoperative, will definitely cause over heating (1955/56 BIRD).

2nd EDIT -

https://thunderbird.us/

 

[55blacktie]

The cheap, infrared temperature readers aren't particularly accurate; my HF gun can be off by several degrees.

 

[zuburg]

I’ve just recently rebuilt this car. Remanufactured engine, all new hoses and belts, new large opening thermostat, new coolant, and even installed the special high flow water pump with the two impellers.

I do have the original 4 blade fan and original water pump spacer. I do know plan to increase the RPMs on my next test to confirm the coolant is circulating. I have read about the smaller pulley, that might be next.

Will it only overheat on days with very high temperatures like 85 degrees or higher?

 

[Late model]

Zuburg,
After reading these posts again I would like to circle back to the original post. I still see two things in there strongly indicate a radiator problem.
1. Mice made a restaurant out of the radiator while it was sitting for a long time.
2. When checking the radiator temps with a temp gun, if the readings were accurate, the difference between the inlet and outlet temps was 48F. This much higher than the usual 10 to 15F in a typical radiator. The link below has some great info on cooling system operation, especially in the first two pages.
https://www.enginebasics.com/Engine Basics Root Folder/Engine Cooling Pg3.html
Another concern is which way did the radiator get flushed, from inlet to outlet, or outlet to inlet. I assume inlet to outlet so as to drive the out the mouse dinner out, rather than in.
Because low coolant velocity through the system can also cause high temp drop you need to make sure you have some coolant movement at idle. If you do, then I think the next step is to verify the temp drop with a couple of thermocouples and an electronic thermometer. If it is actually that high, pull the radiator for rodding out or high pressure washing.
Don

 

[zuburg]

I was hoping to not have to drain all of the new coolant and pull the radiator. I’ll finish wrapping up my latest work and do another test and take temps with an IR thermometer & get some data to help decide.

I did flush the radiator from top to bottom. I kept pouring water through until no sign of bird seeds which was over 25 gallon jugs of water.

I heard the early birds did not circulate coolant under 800 RPMs (idle). Is that also the case with the special high flow water pump that has two impellers?

 

[dmsfrr]

....
I heard the early birds did not circulate coolant under 800 RPMs (idle). Is that also the case with the special high flow water pump that has two impellers?

Coolant flow at idle isn't quite that bad but it is less than half of the flow at 1500 RPM.
See this link...

https://www.classictbird.com/pdf/H2O-pump-test-results.pdf
Please excuse the fact that this linked page is nearly 20 years old. The water pump shown was a diy example that was quickly replaced with a much better looking version.

I find myself agreeing with Late model, your initial temperature readings from post #1 could easily indicate poor coolant flow.

Reading through the majority of the comments about overheating I did not see any mention about the baffle plate between the water pump and the timing case cover...

The baffle plate is shown and discussed at the link above.
.

 

[KULTULZ]

I did flush the radiator from top to bottom. I kept pouring water through until no sign of bird seeds which was over 25 gallon jugs of water.

That's not flushing, that's rinsing. If the RAD was (is) that bad, it needs to be tanked, pressure flushed and then flow tested.

The flow test will determine if rodding out (or a new radiator is necessary).

I heard the early birds did not circulate coolant under 800 RPMs (idle). Is that also the case with the special high flow water pump that has two impellers?

All year BIRDS had cooling problems. Measure the DIA of you WP pulley. Your BIRD came (assembled) with a 3- or 4-blade fan?

EXACTLY which pump did you buy and install?

​

EDIT -

CASCO's pump does not eliminate the spacer/usage. It has longer impellers that reach back into the spacer to move water.

Incorrect statement removed from text -

Was it one of CASCO's new castings that eliminates the spacer usage?

CASCO 8501HO - It is used with the spacer ...

 

[KULTULZ]

- Repairing a Radiator by Rodding or Recoring -​

CLICK HERE - https://www.roundforge.com/articles/repairing-radiator-rodding-or-recoring/

 

[paul2748]

CASCO's pump does not eliminate the spacer/usage. It has longer impellers that reach back into the spacer to move water.

T
EXACTLY which pump did you buy and install? Was it one of CASCO's new castings that eliminates the spacer usage?

 

[dmsfrr]

... Your IGN SYS is LOAD-O-MATIC and if the ignition advance is inoperative, will definitely cause over heating (1955/56 BIRD) ...

Photo example of a Loadomatic distributor, used on Y-blocks from '54 thru the '56 model year.
Four pins with two springs.
If the plate the points & condenser are mounted on is stuck or does not move with vacuum applied, the ignition timing is not advancing. This will make the engine run hot.

https://www.ctci.org/gilsgarage/cracked-exhaust-manifold/
.

 

[KULTULZ]

CASCO's pump does not eliminate the spacer/usage. It has longer impellers that reach back into the spacer to move water.

My mistake and stand corrected.

My reading comprehension seems to be lacking ...

 

[KULTULZ]

one other question about the radiator. I was looking at the overflow tube coming out of the side of the neck where the radiator cap goes and noticed it was loose and a small piece of plastic tubing was inserted into the overflow tube and inserted into the hole in the neck, more or less attaching the tube to the neck. Is this how it is supposed to be or was this some kind of hack by the previous owner?

Overflow Tube - CASCO 8005b

 

[zuburg]

What if you have a 13 # cap, which is what I have. That was supposedly the right one for this car.