New (refurb) Teves accumulator - what improvement should I expect?

[KTEDSEL]

My recently acquired 1990 Reatta had the original Teves accumulator. Brakes worked fine, but the pump activated after each press on the brake pedal. I was advised that was the symptom of a failing accumulator which should be replaced before it failed completely. So I bought an accumulator from ECRP.

 

While the hydraulic system was open, I took the opportunity to replace the accumulator with a new (perhaps refurbished) Teves accumulator, changed all 5 rubber brake hoses, and flushed out the old dark brake fluid. With all tasks accomplished, I am surprised the electric brake pump activates as often as it did with the old accumulator. After the system is pressurized, the pump activates again on every second brake pedal press. I had been advised, perhaps incorrectly, that a good fully pressurized accumulator should give 3 or more pedal presses before the pump re-activates. I assume these more frequent pump activations will cause the pump to wear out sooner.

 

What should I expect? Is it normal for a fully pressurized new accumulator to only be good for one pedal press before activating the pump to re-pressurize? Or could something else be faulty?

 

 

[EmTee]

When the brake is applied, do you have a hard pedal (i.e., no air in the system)?

[2seater]

To truly know what is going on, the actual brake booster pressure needs to be measured. The operational pressures may be off, although I have found the pressure switch to be very reliable unless there is fluid leaking into the electrical connection. The amber and red lights extinguish at ~1700 psi, the pump shuts off at a fully pressurized ~2650psi. The pump restarts when the pressure falls to ~2000psi and cycles back to full. If the pressure falls far enough, the red/amber lights will illuminate at ~1500 psi. The accumulator gas charge should be within the 550psi minimum, to 1100psi maximum. 

One other area is what constitutes a "pump". Pic below of my homemade pressure test rig.

 

[Barney Eaton]

Sounds like you have done all the right things......... 

Your symptoms sound like the pump may not be turning on and off at the correct pressures.

2seater mentioned the pressure switch and the first test there is to unplug the electrical connector and 

check for moisture....if a seal has failed, fluid can leak into the switch and affect the pressure settings.

Another possibility is the replacement accumulator.   I was not aware that anyone was refurbishing them, and

a "new" unit that might have been setting on the shelf for years could have a low precharge.  

Go to www.reattaowners.net  (Ronnie's site) and you will find lots of info, test, etc.

[KTEDSEL]

1 hour ago, Barney Eaton said:

Sounds like you have done all the right things......... 

Your symptoms sound like the pump may not be turning on and off at the correct pressures.

2seater mentioned the pressure switch and the first test there is to unplug the electrical connector and 

check for moisture....if a seal has failed, fluid can leak into the switch and affect the pressure settings.

Another possibility is the replacement accumulator.   I was not aware that anyone was refurbishing them, and

a "new" unit that might have been setting on the shelf for years could have a low precharge.  

Go to www.reattaowners.net  (Ronnie's site) and you will find lots of info, test, etc.

The replacement accumulator is a recent purchase from East Coast Reatta Parts ($649). I'm not sure if it's an original NOS Teves, but it has the same shape and size as the original, but a different warning label the the original (see the photo). I'm not sure if the accumulators ECRP sells are old stock originals.

 

After bleeding out the old fluid, I have a firm pedal, no air in the system. The pressure switch electrical connector is dry inside. The brake warnings lights on the IPC go off after the system pressurizes at startup. The brake warnings don't illuminate while driving, even with repeated brake applications.

 

As for Ronnie's site, perhaps you mean https://www.reattaowner.com/roj not www.reattaowners.net - the latter URL is not functional. I will browse ROJ.

[KTEDSEL]

UPDATE: I chatted with Marck Barker about the new accumulator and did more tests as he suggested.

 

My initial test which caused the pump to activate after one pedal press was maximum pedal pressure such as a full bore emergency stop. Marck said try milder pedal presses such as a typical traffic stop: after 6-7 of those pedal presses, the pump activates and runs for 6 seconds. The fluid level in the reservoir drops exactly 1/2" from full when the accumulator is fully pressurized.

 

So apparently all is well, hopefully no problems with the new accumulator.

[2seater]

Those readings are spot on for a new accumulator in regular service👍

[Ronnie]

I think it's good practice with a Teves system to try to plan your stops so you can apply the brakes a minimum number of times to keep the pump from running anymore than necessary. Once you press the brake pedal, hold it down until you come to a stop when practical. I'm not saying do a one pump panic stop every time to avoid letting up on the brake pedal. Just saying you should be cognizant of how you use the brake pedal effects the accumulator pressure.
 

In the old days we got in the habit of pumping the brakes a few times to get a full pedal before coming to a stop. Doing that with a Teves system is not necessary and only wastes pressure stored in the accumulator causing the pump to run more often. Just my 2 cents.

[KTEDSEL]

36 minutes ago, Ronnie said:

I think it's good practice with a Teves system to try to plan your stops so you can apply the brakes a minimum number of times to keep the pump from running anymore than necessary. Once you press the brake pedal, hold it down until you come to a stop when practical. I'm not saying do a one pump panic stop every time to avoid letting up on the brake pedal. Just saying you should be cognizant of how you use the brake pedal effects the accumulator pressure.
 

In the old days we got in the habit of pumping the brakes a few times to get a full pedal before coming to a stop. Doing that with a Teves system is not necessary and only wastes pressure stored in the accumulator causing the pump to run more often. Just my 2 cents.

It seems Cardone rebuild the Teves units, but not cheap. The electric pump gets a heavy workout after so many years of service. I wonder what refurbishment Cardone does? They do rebuilding of several components for our Reattas. https://www.cardone.com/search.php?search_query="AA1DKYR9~"&year=1990&make=BUICK&model=REATTA&sort=alphaasc