Packard Forum Index » V-8 (1955-56)

The windshield wipers on my 1956 400 do work, but they are painfully slow. I seem to remember that vacuum wipers tend to act this way, but I don't remember how to fix them. The older cars, I know, had a vacuum booster on top of the fuel pump, but this 400 has only a single-acting pump.

Any advice on this would by appreciated.

Steve in Indiana

The motor itself may need some oiling or rebuilding, but also check the linkage. Each joint may need to have the old caked grease cleaned, and new lithium grease applied.

The vacuum booster is located within the engine. The booster and the engine itself supply vacuum to the divider valve on the firewall from whence it is supplied to the vacuum motor. Make sure all of those hoses are good. Oil the pivots and pulleys under the dash as West suggested.

Then send the motor off to Mr. Ficken, who advertises in Hemmings for a rebuild. You will be stunned how well the wipers will work.

Agree with West and Ross but one other thing to mention is unless you know the history of your car and can rule it out, there could be a possibility that the PI or one of the similar reworks of the oil pump might have been installed and the aux vacuum pump in the crankcase removed. The PI pump was a heavily promoted "cure" for intermittent lifter noise back in the 70s and 80s and there is no telling how many cars are running around with it installed. Depending on the installer, there is no visual way to tell if the mod has been done without removing the oil pan. You can feel the vacuum in the aux line if the engine is running and pump is working though.

Not having an aux vacuum source would not be the reason for your slow wipers since the extra vacuum only helps when the engine is under load or throttle is near full open. In addition to a possibly old leaking hose causing a vacuum leak, on some cars the installer of the reworked pump left the old vacuum lines to the original aux pump completely untouched. Rather than removing or blocking the line they just relied on the external check valve in the aux line to prevent vacuum leaks. After many years those valves could be gummed up or failing allowing slight leaks.

If your car has been modified either with the PI pump or todays Olds pump and you need or want to have an aux vacuum source, a dual action fuel pump can be added and the old line to the aux pump rerouted slightly and used for the new source. By doing that you can keep the original balance valve and hoses intact and all ports functional.