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1956 vacuum wipers gone nuts in hot weather!?

Started by Hillbillycat, August 03, 2020, 03:21:43 AM

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Hillbillycat

The wipers on my 1956 went nuts on this super hot Saturday evening after a 60 mile trip on the Autobahn at 75mph. They started operating without being turned on when we left the Autobahn and were in stop and go traffic.
What´s going on here?
Had to pull the hose and plug the fitting to make them stop.


And yes, I had vapor lock symptoms while trying to accelerate  on a grade at 75mph. Flipping the switch of my auxiliary electric fuel pump did the trick to cure that issue.
Are vacuum wipers prone to start operating when ambient temp i the engine bay is getting super hot?

J. Gomez

Quote from: Hillbillycat on August 03, 2020, 03:21:43 AM
The wipers on my 1956 went nuts on this super hot Saturday evening after a 60 mile trip on the Autobahn at 75mph. They started operating without being turned on when we left the Autobahn and were in stop and go traffic.
What´s going on here?
Had to pull the hose and plug the fitting to make them stop.


And yes, I had vapor lock symptoms while trying to accelerate  on a grade at 75mph. Flipping the switch of my auxiliary electric fuel pump did the trick to cure that issue.
Are vacuum wipers prone to start operating when ambient temp i the engine bay is getting super hot?

The only possible issue will be with the slider at the motor that allows the vacuum to enter the motor depending on the position of the switch. The slider has a small spring metal bar that applies pressure to keep a good seal, but is not 100% reliable.

Maybe the high temp inside the engine bay cause the spring to weaken and allow the vacuum to enter the motor.   ???

Also, if you have the coordinator this could also failed, but mostly it would cause vacuum leaks.   :(

Good luck..! 
J. Gomez
CLC #23082

fishnjim

Probably one of the "flappers" failed.   There's a control block for the vacuum and if it by-passes they'll get vacuum and starting working.   Or it's in the switch.   Another reason I don't like original.   
The bad news, they work!   50:50 they would have died.

cadman56

If the wipers started working that means you are getting vacuum into the wiper motor.  The very first thing I would check is if the control cable came loose and let the sliding valve move towards the open postition.
Jose could be correct, but I would have thought a vacuum leak would have occured if the spring was out of whack.
The little vacuum device on the forewall just acts as a shuttle valve, allowing the stronger of two vacuum sources through.
1956 Cadillac Coupe deVille (sold)
1956 Cadillac Convertible (sold)
1956 Cadillac Eldorado Seville (sold)
1967 Cadillac Eldorado (sold)
1968 Cadillac Convertible (Sold)
1991 Cadillac Fleetwood Brougham dElegance
Larry Blanchard CLC #5820

Roger Zimmermann

I would love to have wiper working at 120 km/h in dry weather! Obviously, your wiper motor is in a very good condition and you have enough vacuum to let it operate.
As other wrote, the slider was out of the rest position for an unknown reason.
1956 Sedan de Ville (sold)
1956 Eldorado Biarritz
1957 Eldorado Brougham (sold)
1972 Coupe de Ville
2011 DTS
CLCMRC benefactor #101

Hillbillycat

Hi Roger,

you got me wrong. They didn't work at 120km/h.  They started when we hit town and crept around slowly searching for a parking lot. But the windshield was dry as a bone indeed.
The control cable was not loose. I was able to switch between long and short stroke action while they were nuts.
I had reconnected the vacuum hose to the wiper after the car had sat for two hours and everything was back to normal.

Hillbillycat

Mystery solved. It was the coordinator that was engaging the wipers.
Now it´s either the valve block on top of the washer jar that is defective or the vacuum switch under the dash. I have constant vacuum on the coordinator hose fitting on the washer jar valve block. Any ideas?

cadman56

Disconnect the inside dash control line out on the washer pump.  There should be no vacuum present on that line unless you push the button inside the car.  If there is no vacuum  the fault is probably inside the washer pump assembly.
At least you know know the coordinator and wiper motor works, that is a huge plus.
1956 Cadillac Coupe deVille (sold)
1956 Cadillac Convertible (sold)
1956 Cadillac Eldorado Seville (sold)
1967 Cadillac Eldorado (sold)
1968 Cadillac Convertible (Sold)
1991 Cadillac Fleetwood Brougham dElegance
Larry Blanchard CLC #5820