Packard Forum Index » Pre-War (1899-1942)

I'm just throwing this out there, but someone else on this Forum had an overheat problem and after trying everything under the sun, he discover that his Radiator Cap was the problem. I don't remember if it was the wrong cap or if it was just bad.
Wes

Thanks Wes. I changed the radiator cap. The one that is on it has a rubber seal. The previous was cork. It fits on tight and there is no leakage. It is not a vented cap.

I'm not sure how to conduct a radiator flow rate test on the radiator..... or what you would compare it to. I installed the radiator/radiator frame assembly to the car frame 15 years ago. If my memory serves me right, there is 1 large bolt that holds the radiator to the rad frame. How would you remove the radiator without removing the grille assembly? Do you think it will come out through the engine bay after the water pump/fan was removed? The sheet metal fit up was a nightmare with this car. Can you provide the details of how to accomplish this without removing the fenders (and brackets), headlights, front bumper, hood, inner fenders, etc.? Thanks. Daryl

What you can start with is flushing the radiator from bottom to top and see how much junk comes out.

Early cars up to about 40 do not have a pressurized cap, thus the cap is immaterial in the operation of the cooling system. As there has been temperature scans of the inlet/outlets of the radiator with a large temperature differential/drop there seems to be adequate flow. A clogged radiator would show a small differential.

When I had my 37 120 in the 60's I could remove the front clip in 20 minutes....but not the first time as I left out some bolts and of course everything was loose. I put a 41 engine in it and the fan to radiator clearance was 1/2" or less, needed to remove front clip for Wp/fan belt
work. A great $50 car!!

1 Remove large nut under rad and leave out the cotter pin if there is one
2.Unplug headlight wires
3.remove fender/runningboard bolts (6)
4.Remove fender to cowl bolts (4 or 6)
5.Remove hood
6. disconnect hood rods at radiator
7. Disconnect radiator hoses
8. Then disconnect anything you forgot to disconnect ????

Get a friend to lift at one fender while you lift at the other. Lift fenders over wheels and move clip forward.

Before you do this eliminate all other possible sources of overheating and double check everything.

Remove a freeze plug from the lh side of the engine and see if there is rust/scale in the water jacket. Keep in mind the jacket goes about 1" below the bottom of the opening.

There is one other thing that can change in an instant, the head gasket can develop a leak. Even if you've checked it, get a kit to analyze the cooling fluid to see if it has combustion gases in it.

On radiator flow, a quick check is to fill the system to about 1/2" below the neck, idle the engine to get a starting point and then increase rpm to 2000 or so. If the waste rises appreciably or overflows into the drain tube then the rad may be clogged. Poor man's flow check

You say the water pump looks ok. Good. Sometimes the impeller is not in the right position on the shaft. It will not function properly if it is too far away from the back of the housing. You might want to check for this. Use a piece of puddy on the back of the impeller reassemble the pump, disassemble it and see how much the puddy has been compressed. There should be very little clearance. I don't know how much, but someone here will know.

Another item to check is the distributor vacuum advance chamber. Don't recall if the 120Bs have one, but a leaking chamber can deal all kinds of bad things. Easy enough to check by disconnecting the line and sucking on it and holding it. If it does not maintain a seal it is bad.

Surely you have a water distribution tube in the engine block. It is easy enough check after the water pump has been removed.

I would certainly re-torque the cylinder head nuts.

Your radiator cap is a non-pressurized type.

Hope this helps.

(o[]o)

If all else fails, replace the Bendix Treadle Vac with a dual master cylinder

..and for goodness sake, perform the service bulletin to notch the gas tank filler tube...

Good to see Fred has a sense of humor!

I would flush the system with oxalic acid, which in my opinion is the best system to use on a car. Its too bad that Du Pont stop making their kit that had it in. I've posted eles where on this site how to go about using it.

Or if all else fails you could sell me the car - I have $500 waiting to spend on it. (LOL)