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MY 1957 rebuilt 365 is overheating, any suggestions

Started by 57 Coupe, March 30, 2016, 01:26:15 PM

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57 Coupe

I am ready to drive my '57 Coupe but it continues to overheat.  The engine was rebuilt & has only 365 miles on it since the rebuild.  I changed out the original A/C to a Vintage air system, put an aluminum radiator in with a built in trans cooler, and it has the A/C shroud.  Sometimes it will overheat & coolant with come out of the overflow but not always.  If sitting & running or in slow moving traffic, it overheats.  I have checked the temperature when it starts to approach the third line, & it shows temperature to be about 210 degrees.  All suggestions would be appreciated.  Thanks, T. Schaub #29227

Cadillac Jack 82


Is your carb running lean?  That could cause it.  What about your timing?
Tim

CLC Member #30850

1959 Cadillac CDV "Shelley"
1964 Cadillac SDV "Rosalie"
1966 Oldsmobile Toronado "Sienna"

Past Cars

1937 LaSalle Cpe
1940 Chevrolet Cpe
1941 Ford 11Y
1954 Buick 48D
1955 Cadillac CDV
1955 Packard Clipper
1957 Cadillac Series 62
1962 VW Bug
1962 Dodge 880
1966 Mercury Montclair
1967 Buick Wildcat Convertible
1968 Chevy Chevelle SS
1968 Plymouth Barracuda
1977 Lincoln MKV

Dan LeBlanc

Do you have the a/c idle speed up control installed and working?

When these cars were new, the solenoid was fitted to the carburetor.  If the car was standing with the a/c on, the owner's manual instructed you to put the car in park or neutral.  The solenoid would speed up the idle to increase cooling, charging, and refrigeration.  It could be as simple as not enough air flow through the radiator in your case.

What fan are you running?  How many blades? 
Dan LeBlanc
1977 Lincoln Continental Town Car

Walter Youshock

Who rebuilt the engine?  I'd be asking them as well.

Any particular reason for changing the radiator and trans cooler?
CLC #11959 (Life)
1957 Coupe deVille
1991 Brougham

J. Gomez

Thomas,

You mention several changes you made to the cooling and A/C system but how about the most obvious “water pump”, water hoses etc.?

Also have you done any pressure or leak test on the cooling system?

If you check your Service Manual there are a few test that can be done in your case, there should be one in particular listed for air gasket leakage test. Although today you can have it done at any auto part store by sending a sample of your antifreeze for testing.

Just a few suggestions..!

Good luck.
J. Gomez
CLC #23082

savemy67

Hello Thomas,

As others have indicated, there could be a number of causes to your overheating problem.  However, your description of the symptoms suggests to me that the flow volume of circulating coolant is insufficient to keep the car cool at low RPM, and or the radiator is not sized appropriately to transfer enough heat to the air at low RPM.  Do you know if the car exhibited the same systems before the engine rebuild and radiator replacement?

If coolant flow volume is insufficient, I would check that all your hoses and any coolant connected systems (e.g. heater) are in good shape with no restrictions, also check the waterpump as J. Gomez suggested.  Are the pulleys the same as the originals?  Larger pulleys will slow down the fan, thus reducing air flow through the radiator.  Is the replacement radiator located the same distance from the fan as the original?

I am curious as to how you checked the temperature.  Did you catch the overflow in a container and use a thermometer?

Respectfully submitted,
Christopher Winter
Christopher Winter
1967 Sedan DeVille hardtop

Walter Youshock

CLC #11959 (Life)
1957 Coupe deVille
1991 Brougham

57 Coupe

Thanks to everyone for their recommendations.  The thermostat is a slant super cool 180.  The pulleys are all the same.  The reason for changing out the radiator & trans cooler was to try to prevent this overheating issue since I changed the original A/C to a Vintage Air system.  The water hoses were changed out but the original water pump was used as the car only has 41000 miles.  Will try the pressure or leak test non the cooling system.  Does anyone recommend where to either send the original water pump to be rebuilt or where a new one may be purchased?  Continued thanks for your recommendations & I will follow up to let you know what
the results are.  T. Schaub

Walter Youshock

What's idle in Dr set to with air off?  Is it overheating with air on, off or both?

With the condenser in front of the radiator, it might be restrictions the new radiator.  I'd figure a different condenser was part of the new air kit.

O NOT rule out a stuck thermostat.  I had s brand new one fail within a week of installation.  Shop manual calls for a 160 thermostat standard with "high opening" at 180.  Cap is rated at 12 - 15 lbs.
CLC #11959 (Life)
1957 Coupe deVille
1991 Brougham

59-in-pieces

Thomas,
A few thoughts:
Walter asked about the thermostat - is the 180 per specs (don't get offended, but is it in right side up, or upside down - it happens, trust me).
Have you actually tested it in hot water at 180 degrees, and did it open - even new cheap foreign ones fail right out of the box - don't boil the water creep up on the heat, and see at what temp it actually opens.
You said that you replaced the radiator hoses - and maybe some others?
Did you make sure the replacements had the spring inside - in the right place, without them the hoses have a tendency to collapse when the hose heats up and gets soft - down goes the flow.
Have fun,
Steve B.
S. Butcher

gary griffin

The transfer of heat depends on the difference between the temperature of the air and the temperature of the coolant. A 15 PSI thermostat raises the boiling point to about 250 degrees. The purpose of raising the boiling point is to create a greater differential between the coolant and the air going through the radiator creating a greater differential and better heat transfer.  I would get  a infra red thermometer at HF for about $30 and look for hot and cool spots in the engine and in the radiator to figure out where the problem is. What is the temperature of the water entering the radiator and the temperature of the water leaving it?
Gary Griffin

1940 LaSalle 5029 4 door convertible sedan
1942 Cadillac 6719 restoration almost complete?
1957 Cadillac 60-special (Needs a little TLC)
2013 Cadillac XTS daily driver

Jeff Rosansky CLC #28373

Stupid question, is the fan on backwards? I rebuilt my engine and used the old radiator cap.... It was the wrong cap but I never noticed so check that.... I made that miatake.
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

cadman56

You say it sometimes overheats.  I think Steve B. & Walter have hit on the problem.  I bet the thermostat may be sticking.  Check to see what vacuum you have at idle, timing may not be correct.
Another thought, is the overheating only when using the A/C?
And don't forget, if your engine builder builds engines like I do they are pretty tight.  That will cause extra heat until they get broken in. 
Good luck, Larry
1956 Cadillac Coupe deVille (sold)
1956 Cadillac Convertible (sold)
1956 Cadillac Eldorado Seville (sold)
1967 Cadillac Eldorado (sold)
1968 Cadillac Convertible (Sold)
1991 Cadillac Fleetwood Brougham dElegance
Larry Blanchard CLC #5820

fishnjim

"Overheating" is a misnomer.   It's simply trying to remove the heat load by raising coolant temperature because it can't overcome the resistance of the cooling system.   You have to provide enough "cooling" to prevent "overheating".   Not uncommon issue with older cars with or without mods.   
They weren't all that well designed back then like today and making changes is widening the potential problem landscape.   I assume you have all the flow and other operating issues correct.   If the water pump wasn't rebuilt, or a new impeller installed, I'd look there also.   They edges tend to rust down in size reducing efficiency.
The most common issues are "fouling" and air flow when cooling is borderline.  Since the motor was rebuilt, the motor heat transfer surfaces should be free from rust so motor is probably transferring heat very well to a weak cooling system.   The radiator, however, may not have been cleaned or recored, from what was/was not reported.  It was common to just solder off leaking parts so it may not be a full area unit either.   Any accumulation of rust or scale will hamper it's ability to transfer heat out.   They were generally thicker wall than they are today, so are a bit more sensitive to heat transfer coefficient(fouling) issues.   Then you put a modern A/C cooler in front dumping warmer air to a compromised system and it makes things worse.   (transfer rate = [coefficient] x [Area] x [Temperature difference])   Air velocity has a positive effect on coeff in finned exchangers.   The refrigerants in use then vs now are also a factor.   I doubt you're using R-12 as originally.   The temperatures at which they operate are different, so the design must change a bit.   Stacking the exchangers couples one to the other, so A/C issues can effect the engine cooling and vice versa.
It'll take some diligence of eliminating heat sources and maximizing cooling to resolve this.  The interiors weren't as air tight as today so the A/C load can be large at times.   I'd speak with the vintage air folks who deal with this alot.  It might be as simple as changing the compressor pulley size.   Or as demanding as having to insulate and minimize air leaks in the interior and replacing some other things.   If improving the radiator doesn't solve it, you can put an thermostatic electric fan on the front to maximize air flow but has to be sized properly or it'll make things worse.   I suspect the modern A/C exchanger doesn't allow as much through air flow as the old one blocking the radiator a bit but just a guess.   What is it's size/dimensions in relation to the radiator, etc.   You're probably only talking 10-20% reduction, it's not always a critical problem, so you have to evaluate if it's worth the effort.

59-in-pieces

Thomas,
Larry's comment about the engine got me thinking.
I assume it was a total rebuild, which would have included new freeze plugs.
If they are a reputable firm then likely no problems - they were removed and replaced.
But, if it were done by a quick and dirty shop, they - too often - knock the freeze plugs inside the block and not pull them out to be replaced.
If they were knocked in, the plugs could seriously inhibit the flow of coolant and drive the temp up.
Not that they may admit it, you could get a Pyrometer/infrared thermometer - heat detecting device, they are cheap someone said from Harbor Freight - and see if there are any hot spots at or adjacent to the freeze plug sites.
Have fun,
Steve B.
S. Butcher

jaxops

One other area to check- I had my carburetor overhauled and when it was re-installed it had a slight air leak.  I noticed it when the car down-shifted to stop at a light.  Then the temperature gauge went up. It might have also been not setup properly besides sucking in air from the bottom gasket.  I had it properly sealed and reinstalled and my overheating problem is gone...so far.  Tunep and timing are the first check areas as mentioned ealrier in this post.  Coolant flow is a real suspect in your case.  Let us know.  Look and listen as the car warms up.  Good luck.
1970 Buick Electra Convertible
1956 Cadillac Series 75 Limousine
1949 Cadillac Series 75 Imperial Limousine
1979 Lincoln Continental
AACA, Cadillac-LaSalle Club #24591, ASWOA

Jon S

Does your new down flow radiator have the same cooling capacity as the original radiator?  After being stuck in traffic, does the temperature come back down?  If so, to which mark - 1/2, 1/4?  These cars typically run at the 1/4 mark unless there is a problem.

I'm agreeing with the thermostat prognosis but questioning the new radiator's cooling capacity also.
Jon

1958 Cadillac Sedan De Ville
1973 Lincoln Continental Coupe
1981 Corvette
2004 Mustang GT

Jeff Rosansky CLC #28373

I am not sure about that year, but some cars had shrouds/baffeling between the condenser and the radiator. Is everything there?
Jeff
Jeff Rosansky
CLC #28373
1970 Coupe DeVille (Big Red)
1955 Series 62 (Baby Blue)
Dad's new 1979 Coupe DeVille

CEC #20099

Tom: Cad 365 engines were famous for cracked cyl heads. 56`s had 2 versions of heads, to try and correct the problems. Don`t know if 57`s had the problem solved. Heads cracked between valves, & in exhaust port area. Cracks will cause exhaust gasses to get in coolant, & cause big time overheating. Your engine rebuilder should have checked for this, but many don`t bother.

You should do a combustion pressure test, using a tool & 100 psi compressed air, in the spark plug hole. Thermostat should be removed. Fill with water, apply air to ea. cyl & look for air bubbles in coolant. Air bubbles mean cracks or blown cyl head gasket.

Do the tests& give us the results.

c chleboun #20099