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The only place for a coil spring is up Zebedee's arse.
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Joined: Jul 12 2016
Posts: 747

Yeah, my understanding from earlier in the thread was the plastic washers were replaced by the time they came to build mine in factory.

That's pretty much what I was thinking too - the car stops well enough IMO and I put her dislike of the brakes down to her not being used to it. I'll go back to doing that :P

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Joined: Dec 14 2018
Posts: 76

Well this topic came back up at a good time for me to ask a few questions.

Being new to the P38 I am in the dark about the signs that an accumulator is going away. I have only driven my new to me 2000 10 miles before it went into the garage to replace the heater O rings and refinish the wood-- along with a few other bits which required attention.

I was not thrilled with the brakes in that 10 mile ride-- seemed like it had no feel- a bit wooden and did not stop all that great. Pads and disks look OK.

Did not think about it until yesterday. I had to run a number of heat cycles statically in the garage to burp the new coolant and during all those times everything sounded pretty normal in the engine bay. Yesterday I turned the key to turn on the radio to check out the base speakers which I just reconed, and there was a loud buzzing coming from the accumulator. I mean LOUD. I started up the and the buzzing stopped. I turned her off and turned the key again to the run position (dash lights up)- and no buzzing.

This is the first time I heard this. There are no warning lights going on during the buzzing-- or when I press the brake pedal.

My question-- Is the buzzing normal if you just have been stopping and starting- just running the motor at idle-or is this a sign that the pump is going out? If normal-- does the fluid leak down if not using the brakes with many stops and start ups so at some point the pump has to run hard and loud to get the pressure back up. The brake pedal never got soft- at least I never noticed it since I always put my foot on the brake when I start an automatic.

And-- what is the three amigos? Yeah-- I know- newbee

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Joined: Dec 30 2015
Posts: 1325

The three amigos are the ABS, Traction Control and the erm.. other braking related light that come on when you start up and go off when you start moving (over 4MPG for the ABS light).
They're famous for staying on as a group if you have issues with an ABS sensor or even when your battery is in less than perfect health.

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Joined: Jan 05 2016
Posts: 839

The buzzing is the brake pump - the P38 uses a positive pressure booster system rather than a vacuum assisted system on other vehicles. Partly because of the traction control I guess, and in part I guess it made manufacturing more straightforward between diesel and V8 varients, as the diesel would have needed a vacuum pump running on the engine just for the brakes.

When the car is left, the pressure bleeds out over time, so when you next start up, the pump has to run to build it back up to the point the pressure switch turns the pump off. Then periodically (after a good number of brake applications) the pump will run again briefly to top off the pressure. The pump is quite loud, but without comparing with another or recording it etc, its a bit hard to say if yours sounds normal.

How many brake applications you should get before the pump runs is hit and miss - 4-5 decent applications is probably realistic for a good/new accumulator. If the pump runs every time you press the pedal, your accumulator is no longer holding pressure and needs replacing. Usually accompanied by the three lights lighting up briefly.

Three lights is ABS, TC and the hand brake light

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Joined: Dec 14 2018
Posts: 76

Sloth---

Thanks-- I needed that! Scared the bejeebus out of me--- the pump was so loud -sounded like one of those vibrating airless paint sprayers- or oilless nail gun air pumps.

Hope I never see the three amigos-- yeah- right

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Joined: Jul 12 2016
Posts: 747

MarkTr wrote:

Well this topic came back up at a good time for me to ask a few questions.

Being new to the P38 I am in the dark about the signs that an accumulator is going away.

I found my ABS pump activating with almost every application of the brakes - and sometimes even when sat stationary with and without the brakes being applied.

After a while I found I had sit and wait for my brakes to come up to pressure before driving away. If I drove away too soon I had almost no brake pressure. This wait was usually only 10 seconds or so.

Very shortly after that I found the three lights coming on when the brake pedal was pressed. The three lights are the traction control light, the ABS light and the red one with the ! that comes on with the handbrake (and when the fluid in the reservoir gets low?).

I fitted a new accumulator and all those issues went away. It was pretty easy to fit, it didn't even need a brake bleed afterwards! It just screws off (I used a chain style oil filter removal tool) and screws back on.

Although the issues went away it did nothing for the brake pedal feel. That was the same before and after the accumulator replacement.

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Joined: Dec 14 2018
Posts: 76

Is it a wear item which after 100K miles I should just replace to save the pump?

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Joined: Dec 30 2015
Posts: 1325

I think it probably is. My accumulator was losing pressure at about 98k. When I changed it the pump got an easier life. The test is to let system pressurise and pump the pedal hard, release, wait a second and repeat. If the pump starts running after less than 3-4 pumps the accumulator is starting to age.

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Joined: Dec 30 2015
Posts: 3160

The brake pedal does feel different to a car with a conventional braking system as it is pressure sensitive rather than movement sensitive. That means it will feel a bit wooden until you get used to it but the main cause of a lack of feel is the choice of brake pads. It's no good fitting hard, performance, pads and expecting good brakes until you get them nicely warmed up. Even using standard Delphi pads I've never managed to get the brakes to fade so harder pads are just a waste of money.

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Joined: Dec 14 2018
Posts: 76

Thanks-- sounds a bit like my old Audi S6 Avant I had for many many years. It had a high pressure braking system and the static pump test was the key.

At over 100K mile it is probably a good time to replace. Are there replacement brands to stay away from?

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Joined: Jul 12 2016
Posts: 747

I think there's only one brand to choose from.

I've only ever seen Wabco ones.

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Joined: Mar 22 2016
Posts: 1056

Mark, the noise you describe could also be the EAS compressor, sometimes people put the washers on the mounts the wrong way, re brakes, as yours is a 2000 you’ve got the updated system, the accumulator is an easy change, also easy to check, put an air line on the valve, when you take it off should just be a phhhf, basically it’s a bladder full of nitrogen inside the sphere, if it’s no good your hear a lot of air coming out from the split bladder.

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Joined: Dec 14 2018
Posts: 76

Thanks all--- I have springs so the compressor is sidelined. I bought a Wabco and will change it out just because I like to baseline any new machine I am getting into. Reading old threads is a great way to come up to speed fast about any new machine. Amazing how the last 25 years of the internet has changed so many of my hobbies/passions.

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Joined: Mar 26 2016
Posts: 276

So your next job is to get it off those bloody springs and back onto air??

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Joined: Mar 22 2016
Posts: 1056

OldShep56 wrote:

So your next job is to get it off those bloody springs and back onto air??

Where’s the like button, lol,, πŸ‘πŸ‘πŸ‘πŸ‘πŸ‘πŸ‘πŸ‘πŸ‘πŸ‘

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Joined: Dec 14 2018
Posts: 76

Yes-- that is the plan. Have to figure out how the EAS was bypassed. Going through past EAS bypass threads I found about five different ways to put EAS into manual mode.

My message panel always shows that the EAS is in manual mode so someone did something correctly- unlike a few bits on this P38.

So I started to check out how a PO may have done it. Looked at the BECM wires first. No clipped wires coming out of the green connector or no blue and white wires splice together with a fuse. I found one red wire with a spliced-in fuse on BEMC-- that is it.

I did not see any grounded wires coming off any connectors under the left-hand seat. All connectors to the pump are hooked up. No fuses or relays pulled out of the fuse box. And finally-- no aftermarket boxes or harnesses.

I will take another look under the left front seat and look for any pulled and grounded wires since that seems the easiest way to put the EAS into manual mode.

From then on it is going through and rebuilding all the EAS bits that wear out or fail.

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Joined: Jan 15 2016
Posts: 364

Little update.

We now have a P38 meet every couple of months, so far 10 is the most we've gathered.

One of the guys found himself with no brakes. Fortunately, he was manoeuvring, so no speed involved.

Took the modulator apart to find the washers were in little pieces. So yeah, it;'s worth doing the job for you early owners..

EAS? We put mine back to air over two days.