Packard Forum Index » Post-War (1946-54)

Updated news:
Something is screwy with this problem, right? Rebuilt the radiator which shop says "will cool a Mack truck"!, new water pump, new thermostat, checked timing, vacuum and all ignition components. So now thinking it's the sending unit or gage.

Put in a new sending unit (they're not cheap) and that seemed to fix the hot gage reading.
Pulled the motor and distribution tube was clean, checked cooling channels in block with a flashlight and very little build up.
So hoping that the sending unit was the problem once we fire it up again. Will update later.

Often overlooked when you have suspected overheating is to ignore the gauge and use a reliable thermometer (or IR heat gun) in the top radiator tank to check the temperature - should be within 5? or so of the thermostat rating. Something else that's all too commonly overlooked is to do a gravity flow rate test of the radiator which is the cause of the majority of overheating problems. It's a bit tedious to set yourself up for this test but any good radiator shop should be able to do it. For many years and models the flow rate is given in the specifications; in some years they give both "new" and "service limit".

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Success! Triumph! Coolness!carefree driving !

After having big mystery overheat problem ;

After changing water pump and belt
Re recore radiator flush out
head gasket change
Checking heat distribution tube
Changing to and from water hoses and radiator hoses
New thermostat
Nothing helped ......
Changed to 12 v ,
Checked timing
Had valves adjusted
nothing ;
hot hot hot

Wrong radiator cap ,the brand new shiny one was the wrong part !easy ,
Balkamp 703-1411is correct size
If it's too short it doesn't seal and make any water pressure and the coolant blows out in 15-20 min
hurray

Good to hear. Sometimes we over look the simplest fix looking for the worse.
Wes

Steve, good news on finding the source of the over heating. You are not the first and will not be the last to over look an incorrect radiator cap. I owned a 39 Cadillac 60 Special years ago. It was my first project car in over 35 years. The previous owner had done all kind of "fixes" to cure an over heating problem, including a cobbled together coolant recovery system. Turns out it was an incorrect cap. Enjoy your Packard motoring.

(o{}o)

Glad to hear the problem is solved so simply.

James From at Kanter's took the time to put together a very nice little piece on causes of overheating; radiator cap fit is prominent on the list. If you're dealing with overheating this is a good read and thanks to James for preparing it.

packardclub.org/forum/viewtopic.php?f=6&t=3468