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

Hello to all, this is my first post to the Packard forum. I'm a mechanic, & I'm looking for help in repairing a "shop project", a 1941 180 Touring Sedan (model 1907).
To date I have performed a "light" engine overhaul, radiator rebuild, new chassis wiring harness, & new brake hydraulics.
Currently I am repairing the power window system. It needs cylinders, solenoids, & hoses. The pump wasn't as bad as I expected for 70 years of brake fluid exposure. BUT, I did have to fabricate a seat for the relief valve due to heavy pitting. Now I need to dial it in.
My question is this, what is the maximum pressure that the pump should produce? Right now I have 85-90 psi "deadhead". That sounds way too high - I'd get about 300 lbs force from the cylinder.
Thanks - Any help is appreciated.

120-130 psi and in reverse, a vacuum of 15-18 inches per service counselor Vol 14 #19https://www.packardinfo.com/xoops/html/downloads/SC/SL-VOL14NO19.pdf There is an introductory description and some basic specs and testing info in that article as well.

Thanks for the quick reply. I guess you need that much pressure because of the high ratio-window regulator design.

I needed a small shim under the relief valve spring to get pressure up to spec.

When I checked vacuum, it pulled HARD, almost 30" ! (I expected my vac gauge to implode.) That's a dang powerful motor- those windows should go down just fine.

The big spring pulling them down doesn't hurt either. Stretching that thing is probably why they need so much pressure.

G'day ineffabill,
Just want to say, to PackardInfo.

Using this same topic for further questions:

In service counselor Vol 14 #19, which HH56 posted, it shows a pump with apparently no reservoir and then an oil (brake fluid?) deposit. Many cars of the 40's with hydraulic systems have a pump and reservoir in one unit. Is this pump and reservoir on the '41's common with any other car? (You can tell that I am missing mine).

Thanks,
victor

All Packard hydraulic windows used brake fluid. Pre war pumps are unique and apparently good ones are somewhat hard to come by. They have a separate reservoir container and mount horizontally under the floor. Pump is reversible & turns one way for pressure up to raise and reverse direction for a suction effect helped by the spring to lower. Solenoid valve is inline with the hose to cylinder.

Postwar pumps are vertical and firewall or fender mounted, have an integral reservoir, and only turn one direction for pressure out to raise. Down relies on pump remaining off, just opening the solenoid valve built into the cylinder and spring pressure then pulling the window down.

Interesting explanation Howard. Thanks!

I will have to keep my eyes open for a prewar pump.

Victor

The '41 had a separate reservoir (for brake fluid) mounted to the frame next to the pump. Here's mine... please excuse my favorite scraping implement.

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"The reason no one messes with JD's reservoir tank."


hahah