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

The top stopped working on my uncle's 53 Caribbean. He said the pump "doesn't make a peep" when using the knob to try and raise or lower. I looked at the electric diagram, and read the shop manual, but still don't have a clear understanding of how this whole thing works, or what my uncle should check first.
I know the electric motor pumps hydraulic fluid to the rams to raise and lower the top, but does the switch on the dash control an electric circuit, or hydraulic circuit or both?
Is there a circuit breaker for the pump motor?
Any pointers on what to check first when looking into this. I appreciate any info on the basic operating procedure of the top, or first things to check.
-Looking forward to warmer weather for packard driving.

On 48-54 models there is a circuit breaker and a solenoid on the side of the pump motor. The power comes directly from the battery via a connection on the starter solenoid and thru the CB to the various window (or top) switches. The switches in turn operate the solenoid to turn on the motor. The motor only runs in one direction and pressurizes the lines. While it does not show on the diagrams, on some cars there is also a relay operated by the ign sw. Its contacts are in series with the wire protected by the CB to prevent any window or top operation when the key is off.

For the convertible, there is an electrical switch mounted on the top of a valve mechanism that is in turn bolted to the firewall. The knob connects to a rod which operates the valve and switch mechanism.

As the pump only operates in one direction -- to supply pressure to the lines -- for the top to raise or lower, the valve portion of the assy directs fluid to the top or bottom of the top cylinders at the same time it turns on the pump.

On cars that also have hydraulic window operation, when raising the windows the switches commands both the pump and a solenoid valve at each window cylinder. The pump motor provides pressure to raise the window or move the seat forward. The top is not affected when raising windows because the top valve remains closed just the same as the windows are not affected when the top is operated because their cylinder solenoid valves remain closed.

To lower the windows or move the seat back the switch only operates the solenoid valve at the cylinders. Without pump pressure a large spring and gravity lowers the window or moves the seat back.

Great description.
This car only has only the Power top. No Power windows or seat (iirc), so that makes things a little easier.
Sounds like checking the CB, relay (if there), and signal voltage to the solenoid would be the First steps. My guess would be a Problem with the CB, but then he will have to figure out if something is causing more load to Trip the CB.
Thanks Howard!

I had a similar issue.
It is easy to check the pump & solenoid, as it can be tested by apply 6v to the solenoid and directly to the pump motor.
My problem was in the valve/switch under the dash. The electrical switch is a rotary sliding mechanism that faces upward. It accumulates dirt in the sliding mechanism over the years. It was a simple job to clean the mechanism once I got it out. It was absolutely full of crud. The hardest part by far was getting the hydraulic lines disconnected. After removing the whole unit, I could see that,as an option, it might be possible to leave the hydraulic valve in the car and only remove the electric part (if you are double jointed and have eyes at the end of your fingers).

Thanks Longjohn,
good idea to just bridge the 6v to the solenoid to check the solenoid and pump, and also for the tip that the electric switch can catch crud.
My uncle is waiting for a warm day in Pittsburg to work on this, so I think it will be a while before I get some feedback. Think he is probably shovelling lots of snow now.