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Overheating/cooling system question


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So, last week, I drove my '63 out from Detroit to Chicago. 85-90F, 70mph, AC (just converted to run on R134) on full--and, about 2 1/2 hours outside of Detroit, the HOT light came on. I dialed the AC temp control to low (eg, not quite as ice cold) and cut my speed back to about 60mph, and that seemed to do the trick. Upon arriving in Chicago and letting the car cool, there didn't seem to be any leaks or drop in coolant level. And, fyi, I had the heater core replaced last year. Near as I can tell, I still have the original radiator (and other cooling system components). On the trip back (at 75F), there were no issues.

Is this behavior 'normal' given the age and condition of the car? I've seen folks mention four-core radiators and electric fans, and one friend even suggested I check the thermostat, so I thought I'd survey the crowd to see what--if anything--I might need to do.

Thanks in advance...

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Near as I can tell, I still have the original radiator (and other cooling system components). Thanks in advance...

The simple check is to ensure there is enough airflow coming through--- dirt/debris or bent rad fins can reduce airflow.

If the rad is original, it could have some blockage. You can take it to a rad shop and have them test it. Mine has been re-cored twice over the 50 years. If you re-core the rad, ask if they can upgrade to more tubes across, by reducing the space in-between. I had that done, so with the 4 core and additional tubes it has so much more cooling capacity than original.

It seems if the thermostat were stuck or non-functional you would have noticed a lot sooner than the 2 1/2 hours driving.

Edited by CheezeMan (see edit history)
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You may also wish to check the fan clutch to ensure it is engaging.

In order to check the operation of the clutch I think it is done just by listening. The chassis manual states that "the clutch coil is calibrated so that at road load with an ambient temperature of 80 F the clutch is just at the point of shift between high and low fan speeds". Low fan speed is between 800 and 1200 RPM whereas high speed is approximately 2100 RPM. You should be able to hear the difference when it switches from low to high.

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I agree with all of the above, however I would also check the lower radiator hose.

If it is new, it should be made of material that will not collapse due to the vacuum/suction of the flow through the water pump at highway speed and rpm.

If older or old, it would have a coiled wire within it to prevent closing or collapse above idle, particularly when the hose is hot and soft.

If real old, the wire could be corroded to the the point of disappearing.

If that hose begins to resrtict the flow, temps will rise.

Airflow should be checked first, then water flow and hose condition as well as clutch operation.

Thermostats generally either work or not.

While the A/C creates added load, a properly functioning cooling system, particularly at highway speed and associated air and coolant flow, should be able to handle it with relative ease.

Extended idling with A/C is another matter.

Good Luck, and GREAT to hear someone actually DRIVING the car!!!

That is what I like most about Riviera folks!


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