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Have a 48 Custom 356 that overheats within 15 minutes of driving. Rebuilt the radiator, put in new water pump, flushed the heck out of block but still have problem. Used heat gun to confirm temp going to 180 degrees and then into the red. Has a 140 degree thermostat in it which opens and temp drops, then goes back to red.

Any ideas?

Had this same problem with my 49 327, put in a new radiator that builder said would cool a Mac truck, and same problem, so I just ran it without a thermostat and it was ok.

You didn't mention the water distribution tube. Besides checking all the cooling system, check the ignition timing. A retarded timing will contribute to overheating. Also, make sure the vacuum advance chamber is sound and holding vacuum. A leaking chamber will result in a lean mixture and retarded timing. One other thing to check is the manifold heat control valve. A valve that is stuck shut will cause all kinds of running problems. Good luck.

(o{}o)


...and one more thing, does it have the 5-bladed fan? Some say over heating when running - radiator, over heating when idling - fan.

Thanks, Austin. Will get on it next week!

I also am having overheat issues ,new rebuild ,record rad ,new water pump ,hoses ,thermostat ,still hot right away after few minutes of running , no problem before rebuild !
Head gasket installed wrong? I have a 288 head on the 327
I'll check timing
I have a dual carb manifold maby mixture is too lean? But it runs smoothly

Te get a correct timing setting, the vac line to the dist has to be disconnected and the engine has to be idling slowly. It is very easy to get a false reading if the revs are up and the advance has started to kick in. 5 or 6 degrees retarded makes a huge difference on these flatheads in performance and temperature.

Hi There,

I have a 49' 288 which does the same thing. After driving for 15-20 minutes its starts to get hot and eventually lets some water out of the radiator cap.

Mine has new thermostat and radiator. It has also had the carburettor and distributor fully rebuilt and set up on a rolling road - it runs great, just gets hot.

I will have a look at my fan tomorrow as I can't recall what it is although I am thinking the water is just not circulating enough to cool down ?


Cheers,

Warren

None of these cases indicates the mentioned the water distribution tube being checked. They sometimes are stuck in the motor and hard to remove without making a tool. But at least shove a long rod into the thing to verify it isn't full of muck.

A first step diagnostic is to buy a hand held digital thermometer (looks like a gun) and check for hot spots. In the old days the only easy way to fix these problems was to tape remote thermometers all over the motor. That still may be required if the thing only heats up on the road.

G'day Warren(Wazza22),
to PackardInfo. It's good to see another Aussie on board, but where in Oz are you?

Another few things:

1) I invite you to include your '49 Packard in the Packard Owner's Registry.

2) Putting on my other hat, as Secretary of the Packard Automobile Club of Australia, I invite you to join us. From this link to the PACA Website you can download a membership application if you wish.

3) Give me a call on 0423 171 170 and we can talk "Packard".

Hi Mal,

I am in not so warm Canberra! Great to know there are a few of us about on this fabulous site.

Cheers,

Warren

Back to the overheating...

I checked a few more things out today and discovered the cap was a 4lb short neck!! I have arranged a suitable long neck cap and will test out tomorrow.

I also used a infrared heat gun to check temps when it was warming up and the head temps all along were around the 75 to 85c which is good.

The test of course will be on its next drive.

Cheers,

Warren