Author Topic: 49 Cadillac Electro-Hydraulic Problem  (Read 864 times)

Offline Currell

  • Posts: 17
  • Name: Currell Pattie
49 Cadillac Electro-Hydraulic Problem
« on: July 31, 2016, 10:46:15 PM »
I have a '49 60s with, of course, the electro-hydraulic system for the windows and seat. The reservoir is full of clean ATF. It was working perfectly.  Then, on my next drive, pressing any of the switches up made the window go down. I cannot get them to return. (Just before this happened, the windows would "chatter" back and forth rapidly, and maybe the window would go up with great difficulty). The seat won't work, either.

Any ideas what is wrong?  Currell

Offline Bobby B

  • Posts: 2732
  • Mendham, New Jersey
  • Name: Bob Bender
Re: 49 Cadillac Electro-Hydraulic Problem
« Reply #1 on: July 31, 2016, 10:56:39 PM »
Currell,
   Hi. Did you Bleed the system? What did you change? Did you mix up any of the lines when re-installing? The reservoir does not get filled all the way. You have to adhere to the fill lines on the cup when the system is in a certain position. Do you have a shop manual? It goes into detail of troubleshooting the system.
                                                                  Bobby
1947 Cadillac Series 62 Convertible Coupe
1968 Mustang Convertible
1973 Mustang Convertible
1969 Jaguar E-Type Roadster
1971 Datsun 240Z
1979 H-D FLH

Offline P W Allen CLC# 20193

  • Posts: 383
  • Name: Paul W. Allen
Re: 49 Cadillac Electro-Hydraulic Problem
« Reply #2 on: August 01, 2016, 08:48:11 AM »
Currell,

I agree with Bob. It sounds like you have some air trapped in the system. The fact that the windows were chattering and  went down when you tried to go up, tells me the pump was either not running or not pumping and the springs pull the windows down. To get rid of any trapped air, make sure all windows are all the way down and the seat is all the way back. The springs will push the fluid and most of the air back to the reservoir. This is an open system so air will bubble up through the reservoir and be expelled. This is why it's important not to overfill the reservoir. There may be some air still trapped in the lines, but not a lot. If the reservoir level is correct, the pump should pick up suction and pump fluid. Working the windows up and down and the seat back and forth, should expel any remaining air. Remember, when checking the reservoir for level, all windows must be down, and the seat must be all the way back. If this is not done and fluid is added, the can will end up being overfilled. Good luck with it.

Paul
53 Coupe
Twin Turbine

Offline Joe Vastola

  • Posts: 288
  • CLC Number: 29052
Re: 49 Cadillac Electro-Hydraulic Problem
« Reply #3 on: August 01, 2016, 08:40:50 PM »
Great advice on checking the fluid level as that would stop the windows from going up easily.  However, my money is not on air in the system.  If the pump is working correctly, 250psi will push all the air out each time you engage the pump.  That's how a dry system gets filled initially with no bleeding.

My guess is that the chatter is the system not pumping up to pressure, pressure being relieved, system never reaching required pressure levels, or system slowly reaching the level needed to exceed the spring return pressure.  You did not say there were any signs of leaks and I'm guessing no loss of fluid when you are trying to make it work, so leaks can be ruled out along with, initially, hydraulic hose issues.  Also you can rule out cylinders and cylinder solenoids at this point since it happened all at once to all windows.  You mentioned clean fluid so if it worked after your last fluid change, you can rule out old dirty fluid and probably debris in the lines.

So that leaves the pump.  Starting with the easiest, the first thing to check is that the pressure cap on the pump section that attaches to the pump motor is tight.  That sets the tension on the pressure relief valve.  If the cap is loose the pressure release valve will open too easily and relieve pressure in the system.  You did not mention it but if you recently removed the pump or hoses, make sure the return fluid hose is in the right return port on the pump.  Next easiest, power may be a problem.  Not enough juice and the pump wont make 250psi. Jump the pump with jumper cables directly from the battery and raise a window.  If that works you have some kind of wiring/connection problem.  Clean all connects and check wires. 

From there things are a little harder to diagnose, but it comes down to potential wear or compromised function with a number of primary internal pump parts - worn port plate, worn fluid compression gears (unlikely to go all at once), dirty or bad motor brushes or armature commutator, stuck or restricted pressure relieve valve, corroded pump motor armature shaft or elongated armature shaft channel on the pump section.  All these contribute to low pressure and over time can wear but then reach a point where they reduce the pumps ability to maintain fluid pressure when running and the system stops working.  Invest in an inexpensive pressure test gauge or transmission pressure test gauge and test at one of the pump ports.  Remove and connect it to one of the pressure lines, engage the pump and make sure it gets up to pressure.  If it does not, remove and cap other hose connections so the pump is segregate from the system and test again.  No pressure, pump needs to be rebuilt.  Lots of pressure, start looking at the plumbing.  Best of luck.
« Last Edit: August 01, 2016, 08:54:10 PM by Joe Vastola CLC #29052 »

Offline P W Allen CLC# 20193

  • Posts: 383
  • Name: Paul W. Allen
Re: 49 Cadillac Electro-Hydraulic Problem
« Reply #4 on: August 02, 2016, 07:51:41 AM »
Good points Joe. I've had my system apart working on new side glass, cylinders and hoses. Never had to bleed anything. I'm wondering if Currell has WAY too much fluid in the system? If the reservoir was filled full with the windows up, it would leave very little if any room for the fluid to go when the windows or seat were operated. Not sure how the system would act under those conditions.
Paul
53 Coupe
Twin Turbine

Offline Currell

  • Posts: 17
  • Name: Currell Pattie
Re: 49 Cadillac Electro-Hydraulic Problem
« Reply #5 on: August 15, 2016, 04:59:56 PM »
First, I want to thank everyone for their input. Here is a bit more info...I have had the car eight years, and the window have worked perfectly until now. I should mention that one window, the driver's, has weeped a small amount of fluid over the years, but it has been very minor; the fluid still was right on the line in the container. Would this introduce air into the system?

One of the suggestions was to lower all of the windows, and the seat in its rearmost position, in order to get any air out of the system. I have two windows partially down now, with the back two up. I am nervous about lowering the back two, since they may not go back up, either, if it is not an air in the system problem.  By the way, the pump is working.

Any other suggestions, given the situation as it is now, will be more than welcome. Thanks. Currell
 

Offline Joe Vastola

  • Posts: 288
  • CLC Number: 29052
Re: 49 Cadillac Electro-Hydraulic Problem
« Reply #6 on: August 15, 2016, 08:23:20 PM »
Currell, I continue to be of the opinion that it is not air in the system.  I recently rebuilt the hydraulic system on my 49, all rubber and metal lines, and cylinders.  So the entire system was completely dry and air filled when done.  I hooked up the pump and after a few fills of the reservoir as the system primed all the windows operated.  No bleeding, no trapped air.  The pressure from the fluid when pumped at the necessary 250psi pushes all the air out.   Just had to run the cylinders up and down a few times until they reached the full extension point to get enough fluid throughout. 

I would not focus on the weeping at this point either.  As long as the leak is not so significant as to stop the system from reaching necessary pressure levels, it should be a non issue.  Again my evidence is my system.  I made all of the double flares and some were bad.  Even those leaks were not enough to stop the system from priming and working when I first got it running. 

Lowering the cylinders will only push the fluid currently in them back into the plumbing and then into the reservoir.  Until you figure out your problem, I would not lower the other windows or you may have all stuck in the down position. 

When a pump wears out, it usually keeps running and even pumps some fluid - just not enough to pressurize the system and raise the window. So I have to ask - what did you do to determine that the pump is working? 

 

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