Jump to content

Is my accumulator bad?


DAVES89
 Share

Recommended Posts

These posts were moved from the buy/sell forum to keep from cluttering up AZ Ron's ad for an accumulator for sale. I thought it would be better to start a new thread.

 

I think I might need an accumulator but you are scaring me when you say the pump ran a lot with the spinning wheels accumulator installed. Do you mean the pump ran a lot when you first started the car to charge the accumulator OR it ran a lot when you were driving the car?

 

When I have the key on and the pump has fully charged the accumulator and shut off, I get two pumps of the pedal before I hear my pump start running again. I can't remember how many pumps I get before the red light comes on. Under the same conditions how many pedal pumps did you get before the pump starts with the spinning wheels accumulator installed?

 

I might be interested.

 

 

Ronnie don't you still have an accumulator ball on the Teves Master Cylinder I sent you. Or was that the one you used to help that guy out with. [i thought I sent you another one for him].

Link to comment
Share on other sites

Dave, I'm pretty sure I do still have one on the master cylinder you sent me. That master cylinder and pump (not the reservoir) is filled with fluid and stored away in plastic and cardboard. I was thinking that maybe I should keep that master cylinder intact and ready to install in case of a major failure the master cylinder on my car. That is the only spare accumulator I have.  I really can't afford a new accumulator right now so I thought this might be a cheaper option for me if it would work on my car.

 

There are no good used accumulators around here that I'm aware of. There might be some in the Pick & Pull in Knoxville from time to time but there is a group of people there that have made a day job of pulling easy to ship parts like that and selling them on eBay. Rarely is there a part that is unique to the Reatta in that yard the three times that I've been there.

 

After testing my brakes the other day and finding the pump runs the second time I hit the pedal, I'm starting to worry that the bad accumulator may be putting a lot of stress on my pump by it running too much. I've been planning a long trip across part of the Blue Ridge Parkway and I need to replace the accumulator before I do.

Link to comment
Share on other sites

I have two "new" pump/motors in my inventory. Let me give them a try and see what I have. I also found another at Gibson's but I left it. My thoughts at the time was if I was to grab it that would mean someone else wouldn't be able to fix their car. I know right where it is and could find the car quicker then it would take to remove it [pump/motor].

 I have a vise in the basement but it is too small. I will be seeing my buddy later this weekend as we have to do firewood. We will have time to test both the accumulators and pressure switches.

Link to comment
Share on other sites

I've been out in the garage testing my brakes again. When I first turn the ignition switch on (accumulater depleted) the red light goes off in the normal amount of time but the pump continues to run for a long time before it stops.

 

I actually get about 1-3/4 pedal pumps (PPs) before the pump starts to run. On the second PP the light comes on before the pedal get to the bottom and gets firm. With the switch still on, I average about 10 PPs before the red light comes on again. With the switch off I average about 11 PPs before the pedal gets hard. Do you guys think the problem with the light coming on after 1-3/4 PPs is the accumulator or perhaps the pressure switch?

 

My accumulator was purchased from GMDirect.com in 2007, which is a long time ago, but during that time I've only put about 22,000 miles on it. I'm surprised the accumulator be bad with so little miles driven but maybe the time factor is just as important as miles driven when it comes to a bad accumulator?

 

Do you guys think the problem with the light coming on after 1-3/4 PPs is a bad accumulator bad? OR, perhaps the pressure switch bad causing the pump to start so early? I probably need a pressure gauge on the pump to know for sure?

Link to comment
Share on other sites

I really need to get together with Dave to do a couple more accumulator tests like I did with my test rig. I know Barney on the AACA was doing some fluid level tests based on my findings but that seems to have died? I think the safe fluid drop level is in the 1/2" range as developed over the years as it is the best we have right now. If you have a helper, maybe they could mark the reservoir at red lite out as well as the pump stop to give a comparison of the volumes? The hard part of defining run time is the variation in available voltage from car to car. What I did discover for certain is: if the red light goes out around 1500 psi (check the manual), with a healthy accumulator, that should happen pretty quickly as the gas pressure of a good ball isn't a whole lot below that and the pump reaches that pressure with little volume. Most of the actual working volume is contained above that point so I would believe the pump should run the majority of the time after the light goes out. I have only tested three of them, but the pressure switches I have tested, as long as they were operational, the settings are pretty much right on the book values.

Link to comment
Share on other sites

I am going to put the Spinning Wheels accumulator on eBay in early May but thought this group should get the first shot at it.

Link to comment
Share on other sites

Ronnie I am sending you a new accumulator. It is from East Coast Reattas and I am curious to see how it works. Marck told us that it is a slightly larger size so be ready. If it is a pressure switch you could take the one off the Teves unit you have.With the pressure off it should not leak much.

That accumulator you bought in 2007 could have been original stock. That is why I sold a NOS unit I got from Booreatta back in 2008 because I thought it was original stock.

This one from Marck is less then 1 year old...

Link to comment
Share on other sites

Accumulator ball sent to Ronnie. He has agreed to do a "field test" of the East Coast Reatta accumulator unit. East Coast Reattas is a supplier of parts. The owner is a guy named Marck Barker and he did some research and ordered balls for us to buy. I had ordered one, but never tried it so I asked Ronnie if he would be interested, and he is and is willing to try it for us.

 Thanks Ronnie!

Link to comment
Share on other sites

I really need to get together with Dave to do a couple more accumulator tests like I did with my test rig.

 

I would like to be able to test the pressure on my brake system. Do you know what fitting sizes I would need to make an adapter to add a pressure gauge?

Link to comment
Share on other sites

Quote

 

I would like to be able to test the pressure on my brake system. Do you know what fitting sizes I would need to make an adapter to add a pressure gauge?

 

The steel line is a 3/16" European bubble flare. I just used a short pre-made piece from a Flaps.  You will need an adapter to mate to the high pressure pipe thread tee. A 4000-6000 psi gauge, a needle valve to dump the pressure and a tube to dump the pressure when desired. My setup is designed to dump back to the reservoir or it could be diverted to a waste container to flush the reservoir if desired. 

 

0408170926-00.jpg

Link to comment
Share on other sites

Hal, your setup is what I had in mind. Thanks for posting.

 

Have you tried this... pressurize the system, turn off the pump and then slowly bleed off the pressure until you see a sudden drop in pressure? I believe the the reading on the gauge where the pressure suddenly drops will indicate the pre-charge in the accumulator.

Link to comment
Share on other sites

Hal, your setup is what I had in mind. Thanks for posting.

 

Have you tried this... pressurize the system, turn off the pump and then slowly bleed off the pressure until you see a sudden drop in pressure? I believe the the reading on the gauge where the pressure suddenly drops will indicate the pre-charge in the accumulator.

 

No, I didn't do that, but it does sound reasonable. I kind of went at it the opposite way, but only as a byproduct of checking the volume to reach certain pressure values.  If I get the opportunity, I will set it up again to see if there is a pattern to be gleaned from watching the bleed down.

Link to comment
Share on other sites

I am going to put the Spinning Wheels accumulator on eBay in early May but thought this group should get the first shot at it.

 

Thanks for posting it for sale here first. Someone should grab it before you have to put it on eBay.

Link to comment
Share on other sites

 

No, I didn't do that, but it does sound reasonable. I kind of went at it the opposite way, but only as a byproduct of checking the volume to reach certain pressure values.  If I get the opportunity, I will set it up again to see if there is a pattern to be gleaned from watching the bleed down.

 

I think that should work. We had accumulators on the hydraulic systems in the machine shop where I worked. That is the procedure we used for testing the pre-charge in them. Those accumulators were a lot larger, about the size of a football, but I think the testing procedure would apply regardless of size. They operated in the 2000-4000 psi range like our brake systems do.

 

We called the accumulators in our shop "dampers" because they smoothed out surges in the hydraulic system when valves opened and closed. We didn't depend on them to provide pressure when the pump was turned off. Not only did they provide some reserve pressure when a valve opened to move a large hydraulic cylinder, they also absorbed some of the shock in the system when a valve snapped closed.

 

It will be interesting to see the results you get when you test the brake accumulators that way.

Link to comment
Share on other sites

I setup my test rig this morning and ran the tests on the three accumulators as suggested by Ronnie. I included my original testing posted on the AACA forum further down in this post. In regard to the suggested test, I checked each one twice, with the results below. The 5000 psi gauge isn't calibrated for small pressures but the readings are as close as I could come:

 

A= 400# & 450#

B= 500# & 500#

C= 1000# & 1050#

 

These readings follow the same pattern as the original capacity testing noted below:

 

"I mentioned in another thread that I was going to try to get actual data on the performance of the accumulators I have on the shelf. My test rig utilizes my pressure gauge assembly for testing system pressure on the car, a 500ml graduated cylinder and a used pump/motor assembly. The graduated cylinder is just a cheap plastic Amazon special accurate to +- 5ml with a hose barb tapped into the bottom as the reservoir. I used the same 350ml level as the start of each test to minimize variation. I ran the pump manually with a battery on the bench and stopped at test pressures I chose based on what I believe are close to correct: 1500psi for red dash light turn off, 2000 psi for pump restart via pressure switch and 2600 psi for pump stop. Accumulators A & B are used from my '89 and '90 and C is a new stock one I installed briefly and then replaced with the Spinning wheels larger model. I won't go into the reasons for replacement but there was a clear difference. I ran each test three times but they were very consistent:

 

A: 170ml @ 1500psi, 190 @ 2000 and 200 @ 2600   also 208ml @ 3050 which is the ball pressure rating

B: 155ml @ 1500psi, 175 @ 2000 and 192 @ 2600           202ml @ 3050

C: 60ml  @ 1500psi, 102 @ 2000 and 135 @ 2600            150ml @ 3050

 

As can be seen none of them held close to the .250ml @ 210 bar on the rating stamped into the ball. I believe that is the total volume of the ball from rough measurements of the exterior. When testing, the pressure immediately jumped up to close to 1000 psi upon pump start for ball C, which seems to indicate a full nitrogen pre-charge, much longer for the other two. Please note, all of these accumulators were operational and not causing real issues when removed. One more thing, both the pressure switch and ball were just run down by hand without mechanical assistance as the sealing is done by an o-ring, so no need for gorilla force.

 

The one takeaway I found was the amount of fluid contained between 2000 psi pump on and 2600 psi is pretty small but significantly greater in the fresh accumulator:

A=10ml, B=17ml and C=33ml

 

I don't have my cars out of storage so I cannot define what the precise fluid level change would be in the reservoir, using the amount of fluid listed above, but less drop is definitely better based on what I found.  I should add, as long as there is significant run time, less is better, but a fully flooded one will show very little change in level and a short run time. If there are any suggestions on where I could improve or other types of tests, I welcome the comments."

Link to comment
Share on other sites

2 Seater.  If you like, I could mail my almost-new Spinning Wheels accumulator to you to have it tested.  It might be interesting to see the pressures.  It only has about 200 miles on it.

I will be putting it on eBay in a couple of weeks and when it sells I could pay for you to ship.

I am curious to see how it measures up!

Link to comment
Share on other sites

2 Seater.  If you like, I could mail my almost-new Spinning Wheels accumulator to you to have it tested.  It might be interesting to see the pressures.  It only has about 200 miles on it.

I will be putting it on eBay in a couple of weeks and when it sells I could pay for you to ship.

I am curious to see how it measures up!

 

     I would be happy to test it for you. As luck would have it, I also have a one year old Spinning Wheels accumulator I intend to test but it is on my '90 which is still in storage 15 miles away. I have a stock type junkyard one on my '89 thanks to Dave, but that one is even further away and I haven't tried that one either. If you still would like to proceed with the test, PM me. I am tempted to buy the one you want to sell, but it would be better to go to someone in greater need.

Link to comment
Share on other sites

I setup my test rig this morning and ran the tests on the three accumulators as suggested by Ronnie. I included my original testing posted on the AACA forum further down in this post. In regard to the suggested test, I checked each one twice, with the results below. The 5000 psi gauge isn't calibrated for small pressures but the readings are as close as I could come:

 

A= 400# & 450#

B= 500# & 500#

C= 1000# & 1050#

 

These readings follow the same pattern as the original capacity testing noted below:

 

 

Thanks for doing the bleed down pressure tests.

 

From your results of testing the way I suggested, compared to the results to your capacity testing, I think you have confirmed that there is a direct correlation between the two ways of testing.

 

So, if we can assume that a certain volume, measured in ml, equals a certain pre-charge pressure, I think it should be possible to relate a certain drop in the reservoir to the pre-charge pressure in the accumulator. The amount of drop in the reservoir level in relation to the pre-charge pressure is yet to be determined. I thought Barney was working on it but he hasn't had anything more to say about it. Maybe you could figure it out by testing with an operating Teves unit on a car and comparing the drop in the reservoir level while doing the bleed down test on the accumulators that you have determined are good or bad in your previous bench tests with your current setup.

 

The question that comes to mind is this - is the drop in the reservoir levels between an accumulator in fair condition, and a new one with full pre-charge pressure, going to wide enough that it can be measured accurately on the side of the reservoir?

 

With the container you are using in the current test setup the surface area (diameter) is small resulting in quite a drop in the level of the container when a relatively small amount of fluid is drained out. That makes it pretty easy to measure a small amount of fluid. The master cylinder on the other hand has a much larger surface area which would result in a much smaller drop in the level for the same amount of fluid drained out.

 

If the fluid level drop in the reservoir is wide enough between a good and bad accumulator, a decal with graduations marked for a fair, good and excellent accumulator could be made for visually seeing the condition of the accumulator.

 

I hope at least half of what I just said makes sense. :)

Link to comment
Share on other sites

Ronnie, what you said makes perfect sense. That was my ultimate goal. It is also my concern regarding how precise the measurement will be on the broad reservoir, but only testing will tell the tail. A two step process would be in order, get a known volume on the bench, install the ball and test on the car. I am woefully behind my springtime schedule but will get to this soon.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...