thoughts on Teves accumulator status

[drtidmore]

My entire Teves system was rebuild by Buick about 10 years ago, new seals, new accumulator, new pressure switch. Never had a moments concern with it since and at present it is still working perfectly.

I decided to run the two tests over on Ronnie's ROJ site and the results have me wondering about the accumulator. I get exactly 5 quick brake applications before the dash light illuminates (quickly goes off once I stop braking) and the fluid level is exactly at 1/2" between max full and normal level (i.e. after pump turns off). These two test seem to put me at the edge of acceptable accumulator performance and I am interesting in hearing if this was your Teves unit would you be putting on a new accumulator or allow it to degrade a bit further before messing with it? The accumulator will hold pressure for hours after powering down.

With the really good prices on the accumulator from Ronnie's site, I am tempted to get one, but as they have a shelf life, I hate to get it and have it set until needed.

Thoughts?

[Guest Corvanti]

my $0.02: i would probably wait awhile to replace your accumulator -but- order one now and replace "at your leisure" or when deemed necessary.

from what i've read, i wouldn't think sitting on your shelf for a few months or even a couple of years would make much difference. when i had to do some work on my brake pump recently, i took a good look at the accumulator. it certainly appeared to be "original", and all tested fine. (still have to work on my ABS sensors though)...

[Ronnie]

David, If you are consistently getting 5 pumps before the pump comes on I wouldn't change the accumulator now. Some people have reported that don't do any better than 5 pumps on a new accumulator. There a number of things that could account for that but it's my guess that pressure switches, especially older ones, may not build proper pressure before they cut the pump off resulting in less reserve pressure in the accumulator. Most people are like me and don't have a tester to measure the pressure in the system.

Another reason for a low pump count could be that all new accumulators don't have the same amount of gas pressure inside them when new. You would think their quality standards would be high since these are brake parts but who knows? Then there is the question of how old are new accumulators that we are currently buying? As far as I know we have no way of determining the production date on the accumulators.

Whether or not you should buy a new accumulator now comes down to whether or not you want to buy an insurance policy against higher prices in the future. I personally don't subscribe to that way of thinking on parts that I think will be readily available in the foreseeable future. For me, having to wait on a new accumulator to arrive if mine goes bad isn't a big deal. My Reatta sits in the garage most of the time and is mostly driven on weekends for pleasure. If my Reatta was a daily driver that I depended on for transportation I would probably consider getting an accumulator while prices are low to have it on hand for quick replacement.

The accumulator that is on my car right now was installed in 2007. I'm going out to the garage right now to do the tests on my accumulator. If I get four pumps or more I won't be buying a new accumulator right now. If I get less than four I will be ordering a new one while the price on them is down. I will report back here with my finding. That will give others here an idea about how older accumulators fair on the tests on my website.

Edited January 21, 2014 by Ronnie
Corrected error in text. (see edit history)

[Ronnie]

The following is the results of accumulator tests on my car that had a new accumulator installed in 2007.

Test #1: The pump starts on my car on the 5th pump of the pedal consistently.

Test #2: Fluid level in the reservoir changes about 1/2" as expected.

I won't be buying a new accumulator now... unless the price drops again drastically. The lowest price I remember for them was ~$93.00. That was a couple of years ago.

[Ronnie]

My entire Teves system was rebuild by Buick about 10 years ago, new seals, new accumulator, new pressure switch. Never had a moments concern with it since and at present it is still working perfectly.

I decided to run the two tests over on Ronnie's ROJ site and the results have me wondering about the accumulator. I get exactly 5 quick brake applications before the dash light illuminates (quickly goes off once I stop braking) and the fluid level is exactly at 1/2" between max full and normal level (i.e. after pump turns off). These two test seem to put me at the edge of acceptable accumulator performance and I am interesting in hearing if this was your Teves unit would you be putting on a new accumulator or allow it to degrade a bit further before messing with it? The accumulator will hold pressure for hours after powering down.

With the really good prices on the accumulator from Ronnie's site, I am tempted to get one, but as they have a shelf life, I hate to get it and have it set until needed.

Thoughts?

Wait a minute. I may have misread this the first time. Are you saying the red warning light comes on after 5 pumps or the pump starts after 5 pumps? There is a big difference. The test on my website is talking about how many pumps you get before the pump starts.

[Guest ReattaCat]

ebay has a bunch of GM (Kent-Moore) pressure gauges...most going for around 25$. search "J-35604" but I got mine for 8$. New they go for over 300$... O.o Teeves manual has a procedure for accumulator testing with one of these, simple procedure and probably more accurate than pedal pushes (like *how hard* of pedal pushes? That would make a difference, no?) Chances are, when one of these "goes bad" it's simply a matter of lost pressure, probably due to slow & progressive leakage of the nitrogen over time rather than failure of the bladder. There's no reason why they could not simply be repressurized with nitrogen. It may require a valve be fit but that should be do-able. Many motorcycle rear shock systems run off of high-pressure nitrogen reservoirs and they are all equipped with valves for topping off because, guess what, nitrogen leaks (just more slowly than air, but still...).

[drtidmore]

The dash light that comes on immediately after the 5th firm pedal depression is the warning yellow light, NOT the RED light, so I think we are finding the same results. The yellow light extinguishes within a second or so after the 5th brake application (i.e. no additional brake applications) which is normal as the accumulator pressure rises. I think I am going to hold off messing with the accumulator.

Ronnie, thanks for running the tests on your Reatta.

Edited January 21, 2014 by drtidmore (see edit history)

[B C]

I live in Canada and I'd like to buy an accumulator from the reatta store but the part does not ship here.. could someone be so kind as to purchase one for me and ship it to me. I'll pay shipping of course. PM me if interested, thanks.

Brendan

[Barney Eaton]

I prefer to count the number of pumps you get before the pump turns on. Even with new accumulators, this is usually only 2 or 3. I am still trying to get something from Teves on the date codes. The sent me a picture of the end of the accumulator with all the stampings but it is blurry and in German.

I would like to build a bench tester using a Reatta Teves pump. I could test/evaluate both the accumulator and pressure switch. It would have a reservoir to hold brake fluid that would be made from some graduated container. The pressure gage could attach to the hard line port that goes to the booster.

You would be able to see the start -stop pressure of the pressure switch, and measure the amount of fluid contained in the accumulator between high and low pressure points. This could be logged and accumulators could be graded by the amount of fluid they contain. This is a direct function of the nitrogen charge on the backside of the bladder. A low nitrogen charge allows more fluid to enter the accumulator. This project has dropped on the priority list as I do not own a Reatta with a Teves system.

[Machiner 55]

Chances are, when one of these "goes bad" it's simply a matter of lost pressure, probably due to slow & progressive leakage of the nitrogen over time rather than failure of the bladder.

Not to say this doesn't happen but the bladder can and does fail.

Time to resurrect this thread. Accumulator revealed.

John F.

[Ronnie]

The dash light that comes on immediately after the 5th firm pedal depression is the warning yellow light, NOT the RED light, so I think we are finding the same results. The yellow light extinguishes within a second or so after the 5th brake application (i.e. no additional brake applications) which is normal as the accumulator pressure rises. I think I am going to hold off messing with the accumulator.

Ronnie, thanks for running the tests on your Reatta.

Does your red warning light come on when you first start the car as it should? Something is wrong if the amber light is coming on after 5 pumps. That is not normal and it will prevent the ABS part of the brakes from working in an emergency situation. If the red warning light is working properly the amber light could be caused by the brake fluid level switch. It is in the circuit between the pressure switch and the EBCM. The ECBM activates the amber light.

[drtidmore]

Yes, on start up, both the red and amber brake lights illuminate. Then as that pump runs and the pressure builds up,the red light typically extinguishes just a moment before the amber light. Depending on how long the vehicle as sat, that can take from a few seconds to 20-30 seconds (FSM says unto 30 seconds if more than 2.5 hours since powered)

In reading further in the FSM, I find that there are three pressure switches. The pump switch activates the pumps at 2030PSI and deactivates the pump at 2610PSI. The warning switch is actually two separate switches in one housing. One is a N/C and the other is N/O and both trigger at 1500PSI and 1900PSI. The N/C switch feeds the Teves controller and the N/O switch feeds the BCM. The amber light is controlled by the Teves and the Red light is controlled by the BCM. It would seem in my unit, that the two switches are bit off from one another as it takes an additional 2 pumps to get the RED brake warning light to illuminate. Once I stop the pumping of the brake pedal, the Red light extinguishes almost immediately and the Amber one follows within a second.

So, I get five solid applications of the brake before the Amber light illuminates and per the FSM the amber light does NOT mean that antilock is NOT functional, but that it MIGHT be compromised (yes that could mean NOT functional as well, but that one light has multiple meanings). I am NOT setting ANY antilock related codes during this process nor have I ever set any such codes in the 25+ years of ownership other than just before I had to have it rebuild. Per the FSM the low pressure condition must continue for 50 seconds before any code sets and once I stop pumping the brake, the pump is able to depressurize the accumulator VERY rapidly to above the set points, so that condition never exists during the test. After that nasty ice storm in early Jan, I took the Reatta to a parking lot and tested the antilock operation before trusting it (due to it having been stored). It worked perfectly.

So is there reason to be concerned that apparently I can lower the accumulator pressure to below 1500PSI during the brake pedal pump test?

FYI, the fluid level after depressurizing the accumulator (i.e. 20 or so pumps of brake pedal), is exactly where it should be as indicated by the marks on the reservoir.

Edited January 21, 2014 by drtidmore (see edit history)

[drtidmore]

ebay has a bunch of GM (Kent-Moore) pressure gauges...most going for around 25$. search "J-35604"

ReattaCat, Thanks for the tip. Found the gauge with o-rings as well as the extension adapter. Another tool that I may seldom use, but nice to have in the tool box

Edited January 21, 2014 by drtidmore (see edit history)

[Ronnie]

To isolate the problem I would jumper the fluid level switch to see if the flashing amber light goes away when you reach 5 pumps. Then continue with other troubleshooting options.

Edited January 21, 2014 by Ronnie (see edit history)

[Guest ReattaCat]

Yes, on start up, both the red and amber brake lights illuminate. Then as that pump runs and the pressure builds up,the red light typically extinguishes just a moment before the amber light. Depending on how long the vehicle as sat, that can take from a few seconds to 20-30 seconds (FSM says unto 30 seconds if more than 2.5 hours since powered)

In reading further in the FSM, I find that there are three pressure switches. The pump switch activates the pumps at 2030PSI and deactivates the pump at 2610PSI. The warning switch is actually two separate switches in one housing. One is a N/C and the other is N/O and both trigger at 1500PSI and 1900PSI. The N/C switch feeds the Teves controller and the N/O switch feeds the BCM. The amber light is controlled by the Teves and the Red light is controlled by the BCM. It would seem in my unit, that the two switches are bit off from one another as it takes an additional 2 pumps to get the RED brake warning light to illuminate. Once I stop the pumping of the brake pedal, the Red light extinguishes almost immediately and the Amber one follows within a second.

So, I get five solid applications of the brake before the Amber light illuminates and per the FSM the amber light does NOT mean that antilock is NOT functional, but that it MIGHT be compromised (yes that could mean NOT functional as well, but that one light has multiple meanings). I am NOT setting ANY antilock related codes during this process nor have I ever set any such codes in the 25+ years of ownership other than just before I had to have it rebuild. Per the FSM the low pressure condition must continue for 50 seconds before any code sets and once I stop pumping the brake, the pump is able to depressurize the accumulator VERY rapidly to above the set points, so that condition never exists during the test. After that nasty ice storm in early Jan, I took the Reatta to a parking lot and tested the antilock operation before trusting it (due to it having been stored). It worked perfectly.

So is there reason to be concerned that apparently I can lower the accumulator pressure to below 1500PSI during the brake pedal pump test?

FYI, the fluid level after depressurizing the accumulator (i.e. 20 or so pumps of brake pedal), is exactly where it should be as indicated by the marks on the reservoir.

This is exactly how my cars displays. According to the publication i have (GM Product Service Training manual 15005.02-1B 'Teeves antilock brake system') Both lights come on upon start and when system pressure is achieved they go off. It says up to 1 minute of pump operation upon startup is normal and further that a fault is indicated by the red light *flashing* if the pump runs >3 minutes. Also, it states that further fault conditions occur re; when either light illuminates while driving. The red light comes on when the pressure falls below 1500psi and extinguishes above that pressure. The ABS light (amber) normally stays lit for "3-30 seconds" upon startup. the only fault mentioned for the accumulator vis a vis either the red or yellow light is if they go on *while driving* and *while braking*, even briefly. So...unless that latter is the case, your system doesn't seem to be indicating any faults (at least those faults indicated from the warning light system) from what you describe above.

[drtidmore]

So...unless that latter is the case, your system doesn't seem to be indicating any faults (at least those faults indicated from the warning light system) from what you describe above.

Those are my thoughts as well. Neither light EVER comes on during normal driving conditions, even in stop and go heavy urban traffic. Getting either to illuminate outside of the typical startup sequence is TOTALLY an artificial process (i.e. the rapid braking action test from the ROJ site test). If I even slow down the frequency of the brake depressions, I get NO warning lights. To make the Amber light illuminate, I have to press the brake pedal FAST and HARD with an immediate release and then another cycle as fast as I can release and hit the brake again.

When my Teves system began to ACTUALLY have issues about 10 years ago, it was taking longer and longer to clear the warning lights at startup and I WAS occasionally getting the Amber light during typical braking activities as well as setting the low pressure code on occasion. It clearly was failing. At that time, the local Buick house told me that they no longer had access to new units, but they had a technician certified by Teves and could get all the parts to totally rebuild the unit, so it was no-brainer decision as the only other option was PNP and then I might still wind up with a Teves that had issues.

As I have the accumulator extension and pressure gauge coming my way, I am going to get HARD data on my unit and I will post those results. As Barney alluded to, we NEED correlation between the simple brake pedal/fluid level tests and repeatable hard facts.

Edited January 21, 2014 by drtidmore
removed comments regarding test procedure (see edit history)

[drtidmore]

To isolate the problem I would jumper the fluid level switch to see if the flashing amber light goes away when you reach 5 pumps. Then continue with other troubleshooting options.

Ronnie,

If the brake fluid level dropped sufficiently to trigger the low fluid warning (or a faulty switch), I would get a warning message on the CRT, which is NOT happening. Also, the Amber light is not flashing. When I do the test as I described in my most recent post on the matter, the Amber light comes ON and stays on starting after the 5th brake application until I stop pumping the brake hard and fast. Getting some hard pressure numbers per the FSM tests should provide a lot of clarity to the issue as well as to how to clarify the simple brake test to give a more robust indication of problems.

[2seater]

I made my own pressure tester for somewhat the same reasons as have been stated. Not the Kent Moore tool, but a simple connection to the pressure port where the steel line connects, a pressure gauge and a valve with return line to the reservoir. I had noticed my pump would turn on for a few seconds on one firm pedal application and the fluid drop was about 5/8", so I purchased a new accumulator through the Reatta store and installed it. Fluid drop did decrease to about .45", but the pump will always turn on with only two pumps or one very firm one. It still runs only a few seconds and shuts off. I surmised perhaps the pressure switch was out of range, but checking with the pressure gauge indicated it is exactly per book values, 2600 off and 2000 on. To be honest, I have begun to question the accuracy of some of the test results previously posted. I have never experienced any anomalous brake warning lights, even before the accumulator change. Either the brake system on my car uses more fluid per brake application, my pedal push is "different" than the standard for the tests, the tests have a wide acceptable range, or, the new accumulator has an insufficient charge? The brake system has always performed well.

[Ronnie]

I did the accumulator test on my car again this morning. Once when I first got in the car with everything cold and then again after driving the car a couple of miles in an area that has 4-way stops on each block. I was wondering if using the brakes for a while would make a difference in the accumulator. The test results were the same before and after driving the car for a while.

One thing that I noticed this morning on initial startup was the pump will run for a while and the warning lights will go off, BUT, the pump continues to keep running for a few more seconds before it turns off. I assume the pump is still building pressure in the accumulator. Is it normal for the pump to keep running a few seconds after the warning lights go out?

[drtidmore]

That is normal as the warning lights go out at 1900 PSI while the pump shuts down at 2600 (per the FSM)

[2seater]

I believe that is normal, at least it is on my car. I believe drtidmore made reference to the multiple switches inside the pressure switch. There are lower pressure thresholds for the warning lights, which would seem to indicate the actual required pressure, otherwise the light(s) would come on every time the pump ran.

[Ronnie]

I believe that is normal, at least it is on my car. I believe drtidmore made reference to the multiple switches inside the pressure switch. There are lower pressure thresholds for the warning lights, which would seem to indicate the actual required pressure, otherwise the light(s) would come on every time the pump ran.

The way you describe it works makes perfect sense when I look at the pressure switch diagram and stop to think about it. Thanks.

[Barney Eaton]

Here is a little information from Teves.. They sent a fuzzy picture with German notes, I ask for a translation and based on their reply, the first two spaces on the left are the year code, the next three are the day code, the last space on the right is a QC code.

I am having trouble with the picture they send, will try to post it soon.

If everyone post the date codes they have, the more we get maybe we can figure out the date code. The day code will probably be 001 thru 365, unless they use some internal code that skips weekends and maybe holidays.

......update

Must be a slow day at the Teves help desk.... on a code of NB1838.... they said NB = 1998, 183 is the 183 day of the year.

Here are the ones I have

SW0589

LE1908

c2518

GP1169

GP2119

Edited January 27, 2014 by Barney Eaton (see edit history)

[DAVES89]

Barney why don't you try them again and get all the year codes from 1990 to date.

I would think the if NB is 1998 then NC would be 1999 ND 2000 and so on.

I don't think anyone cares about the day of the year. We just want how many years old ours are.

Here are mine [from inventory, not on cars]

GP2739

GS1290

P2796 [NOS]

[wws944]

I bought one as a spare back in 2011. There are a lot of numbers around the base. I think the one you are interested in is "JZ217". There is a little mark after that which might be a digit, but it is hard to tell. Came in a AC Delco box that has a decal with a 1995 copyright date on it. So at least it is newer than my original 1990 accumulator.

[Barney Eaton]

I actually ask for 1988 until present........ no response so far.