Got a 64 cutlass convertible. Lines are clear and solid. Pistons are new. Thought piston was defective so I have 3 new ones to work with. Replaced Pump/ motor bought off eBay and seems good. System filled with DOT 3 brake fluid.
Problems:
1. Driver side piston travels slower then pass side.
2. Circuit breaker keeps tripping

Making tests with pistons mounted but shaft eyelets not connected to top mechanisms.
Replaced pump/motor with what seems to be a good used one off eBay. Same symptoms as original pump/motor.
Tried replacing driver side with 3rd new piston but still moves slower.
Tried swapping driver side piston with pass side but driver side always slower. All pistons work on pass side. Proves all pistons are good.
Tried reversing both line sets from driver to pass side and visa versa but driver side still slower. Proves both line sets are good.
Tried swapping flow direction by switching line feeds at the pump. Only made down become up and up down.
Tried removing driver side lines from piston then jogged the switch to see plenty of fluid pumping out of both upper and lower lines.
All seems to defy logic.
When all reassembled can't seem to get last bit of air out of lines.
Circuit breaker keeps tripping so have to work switch in short bursts.
Not sure if tripping caused by back pressure of air in system or bad breaker.
Still need to check amp draw.
Manual calls for #11 brake fluid but using DOT 3. Is #11 a thicker viscosity?
Got a lot of hours in on this. Stumped! Can't think of anything else to try.
Little help? Thanks.

 

[QUOTE=64ragcut;564473]Got a 64 cutlass convertible. Lines are clear and solid. Pistons are new. Thought piston was defective so I have 3 new ones to work with. Replaced Pump/ motor bought off eBay and seems good. System filled with DOT 3 brake fluid.
Problems:
1. Driver side piston travels slower then pass side.
2. Circuit breaker keeps tripping

Making tests with pistons mounted but shaft eyelets not connected to top mechanisms.
Replaced pump/motor with what seems to be a good used one off eBay. Same symptoms as original pump/motor.
Tried replacing driver side with 3rd new piston but still moves slower.
Tried swapping driver side piston with pass side but driver side always slower. All pistons work on pass side. Proves all pistons are good.
Tried reversing both line sets from driver to pass side and visa versa but driver side still slower. Proves both line sets are good.
Tried swapping flow direction by switching line feeds at the pump. Only made down become up and up down.
Tried removing driver side lines from piston then jogged the switch to see plenty of fluid pumping out of both upper and lower lines.
All seems to defy logic.
When all reassembled can't seem to get last bit of air out of lines.
Circuit breaker keeps tripping so have to work switch in short bursts.
Not sure if tripping caused by back pressure of air in system or bad breaker.
Still need to check amp draw.
Manual calls for #11 brake fluid but using DOT 3. Is #11 a thicker viscosity?
Got a lot of hours in on this. Stumped! Can't think of anything else to try.
Little help? Thanks.[/QUOTE

I would try running the pump direct to the battery. Put a 30 amp fuse in the test harness. if ok, then breaker or wiring to pump are suspect,

Tim

 

I assume that the pump you purchased is used. If so, separate the pump from the motor, and clean up the shaft. Most likely it has rust on it that is causing it to drag. The pump to motor shaft seal will have a slight seepage, and will allow some brake fluid to get into the motor, causing it to rust internally. Sometimes you can save them by basic cleaning and running it without the pump attached till it cleans itself by running. If you try to disassemble the motor, getting the brushes back in is a bear of a job. Even when new, sometimes one side would move faster than the other side.

 

Worked on the top today. Bench tested motor with NO load drew 12 amps. Not sure if that's too high or not. Any feedback? Made calls to pump sellers but no one knew what a no load amp draw should be. Put pump motor back in place. Tried the suggestion to run separate feed from battery with a fuse. Started with 15 then 25 amp fuse under pressure they both blew. Dug deep behind the vac boosted to get the breaker out. It looked original but was stamped 15 amps. Wow don't understand that. Best advise came from OPGI. guy named Paul called me back said should be a 40 amp. Replaced it with a 30 amp breaker. Also bought a 40 amp if needed. Ran the top up and down and the 30 seems to be just enough.

The driver side still seems to travel a bit slower then the pass side but Best guess is it has some trapped air that is compressing and not responding as quickly as the other. Hoping that air will eventually work out and be fine. Any feedback on the trapped air theory?

Top is going up and down in 30 seconds. But just not quite evenly.

I think it will be ok now. But any thoughts will be appreciated.
Way to hard for something so simple.
Thanks for the replies!

 

If it were mine I would have drained and flushed all the brake fluid out and replaced with transmission fluid when the pump was out,nothing good happens with brake fluid as it ripens with age. I'm surprised that the pump or cylinder guys didn't say something about the fluids when you talked to them.....Tedd