Hi all,
My ABS pump runs for about 3 seconds after nearly every application of the brakes. It runs for the correct amount of time (around 30 seconds) on start-up. I don't have any obvious leaks. Is there anything else I should check before replacing the accumulator? The brakes and T/C work fine and I don't have any lights on on the dash. (except of course for the SRS) I don't want to replace the accumulator unless I am fairly certain that it is faulty because it is a little pricy. Thank you for any help.

 

I can relate, mine is wearing out and I'm not in a huge hurry to replace it, because of the price. My abs pump runs every other brake application for about 3 seconds. It is hard to diagnose 100%, but usually it is the accumulator. Their life span isn't too long either, so if its old, its time for a replacement. Also, the price a new abs pump is even more of a reason to get the accumulator replaced. I think they are about $1k for a new one.

 

I have been shopping around for one. The best price I have found is 230.00. I have found other ones that are much cheaper for other vehicles. There is one for BMWs that is $100.00 on ebay. It looks exactly the same as the LR part and if I understand it correctly, it is just a bladder. It seems like a very simple part. Very tempting. Has anyone tried any of the other brands for these accumulators?

 

What is the BMW Part # I can Get one next time I'm @ my Parts supplier, which will be monday, and I'll directly compare it to a Range Rover one..

One of my Rovers is starting to make the noise after brake application..

 

The BMW park number is 34 33 1 162 054.

 

Well I checked one out today, They are not going to work wrong thread pitch, but dimensionally similar

So what actually happens to the accumulator to make them leaky? I mean they are a steel tank.. I think with some simple cleaning and, clean the threads ect...

 

They start out life as a steel tank with some brake fluid in one chamber, and another charged with nitrogen at 1800 PSI. Over time, the nitrogen bladder is going to have some leakage through the diaphragm. Once they get to about 1300 (or is it 850) PSI, I think they're considered out of spec. Your ABS system is hydraulic and runs at around 3700 PSI. Rave has some info on it. I think the system can tell how long it takes to pump to 3700 PSI, and if that's too short, it means too little nitrogen charge is left (you're pumping against steel instead of nitrogen, the charge is too small to offer the 45 seconds or so of continuous ABS operation needed). It's the same ABS system as those used on trucks and buses, majorly heavy duty, impressive, and expensive to fix...

The rave CD tells how to check it (measuring the ramp rate of pressure increase, and two knees in the curve), but you need a special gauge.

 

Thanks for that little run down.. It was actually really helpful...

There has to be someone that can recharge these puppies..

I'll speak to a friend of mine who recharges our Nitrogen shocks on our race cars.. He could probably help us out..

 

Does the accumulator wearing out have any effect on the operation of the ABS/TC besides the pump running more often? I ask because we are planing a trip North and want to be ready for the snow and ice.

 

I think the total time available would be directly proportional to the volume of nitrogen left at STP. So if no volume left, 0 time, if half, half time, if full, I hear it's 45 seconds. I doubt very much you will need that much time, but it's your call. Maybe do a mud or snow run and try to give your TC and ABS a workout, (spin, brake, spin, brake, etc) and see how long it takes before the traction control quits working correctly. This might give you an idea how much charge is left. It will also be re-charging the ABS while you do this, which will add time to it.

Hopefully someone else can chime in. You might find some info on the Meritor Wabco website.