Teves mk2 ABS - Hydraulic Accumulator Replacement

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nicklee
480 Newbie
Posts: 18
Joined: Wed Sep 17, 2008 1:23 am
Location: London

Teves mk2 ABS - Hydraulic Accumulator Replacement

Post by nicklee » Tue Nov 08, 2016 1:29 am

Hi - I've been a member since 2008, used the wisdom of the forum plenty of times to keep my car on the road, and finally might have a few things to give back...

I've been running a 1992 Paris Blue ES as my only car since 2008 in which time I've stuck about 55,000 miles on it, taking the grand total to 165,000. It's a fantastic little car, Volvo serviced for the first 100,000 miles of its life with the stamps to prove it! As such it hasn't suffered from too many of the classic 480 issues. Admittedly it leaked a bit at the back for a while, and the rear arches are gradually turning to dust, but it doesn't have any electrical issues and only in the past year has the idle started to creep over 1000rpm :D

Now down to business...

Any pre-1993 480 with ABS will have the Teves mk2 system. It's easily identified because it has a black sphere or 'bomb' (a bit bigger than a cricket ball) attached to the top of the unit. This is the hydraulic accumulator and if you have the Teves Mk2 system you'll need to replace it sooner or later. Supposedly they last for around 8 years, which makes me think that mine must have been last replaced shortly before I bought the car.

In brief, the hydraulic accumulator stores break fluid at high pressure (around 2600 psi i think) for use in the ABS system. The ABS pump pumps fluid into the accumulator where it can be used when necessary. This saves the pump from having to do too much work and overheating. The accumulator starts to fail when the nitrogen stored in it (also at super high pressure and on the other side of a rubber diaphragm to the brake fluid) leaks out.

There are two clear signs that your accumulator is failing:
- when you depress the brake pedal (with the engine running) you hear a relay clicking. This is the pump relay activating the ABS pump. Ordinarily you should get 10 or more depressions of the pedal before the pump kicks in to restore pressure in the accumulator.
- when you depress the brake pedal rapidly and with some force the brake fluid light and the ABS light come on together (try it whilst stationary). The fluid light then goes out shortly before the ABS. In this situation brake fluid pressure drops below acceptable levels and the pump quickly attempts to restore it. If this is happening your brakes are less effective.

If you have these two symptoms, it's time to renew the accumulator. Volvo obviously stopped stocking the part years ago, but thankfully the Teves mk2 system was fitted to lots of well-specced mid-late 80s cars. I got an entire ABS unit from a Ford Granada for £30 and whilst the unit itself doesn't fit exactly, there are lots of parts that can be salvaged - the pump and pressure switch primarily. The ABS computer which lives in the boot was also common to all Teves mk 2 equipped cars :)

Now the saving grace here is that Jaguar saw fit to stick the Teves mk2 in the XJ6 - and Jaguar provide great support for their 'classics'! Much better than Volvo ;) So a new accumulator can be bought from their classic parts department. (I can't post the URL but head to jaguar classic parts and search the XJ6 ABS system.)

This is great news because I couldn't find one anywhere else. The accumulator cost around £200 which I don't think is too badly inflated and arrived with instructions on how to fit. It apparently was 'manufactured in Germany for Jaguar' and carried the ATE (Teves) logo, which makes me think that they can probably be got from Teves for cheaper (although I couldn't find the part in their classic parts catalogue - the 480 is in there, but only with the post 93 mk4 ABS system). At any rate it's an OEM part :D

The Haynes is pretty good on the removal/replacement procedure, but here's a quick guide on how to fit the thing (sorry no pics!):
- REALLY IMPORTANT first steps: disconnect the battery negative terminal so the ABS pump cannot operate. Now depress the brake pedal 25-40 times to reduce the pressure in the system. Mine had got so bad that it only needed about 8 before the pedal became stiff. I carried on pressing though and when I removed the accumulator there was still some pressure in the system.
- Now with the pressure reduced you can remove the accumulator. For this you'll need a wrench/ratchet with an 8mm hex (allen) bit. Don't bother with an allen key though, you'll need more torque than you can make with one. In order to get mine twisting I had to give it a little squirt of lubricant, but I guess this should be avoided if possible in order to not contaminate the break fluid. Even though the pressure in the system has been reduced, it'll still squirt fluid as you loosen it, so it's a good idea to put plenty of rags or paper towels around. Most of the fluid heads down onto the ABS unit so try and get something absorbent around it.
- Unscrew the old accumulator and remove it. You should see clear fluid filling the aperture and an inner pipe extending out of it.
- Screw on the new accumulator (by hand at first), making sure that it has a new rubber o-ring fitted. Tighten it off to 40nm of torque. I had to go a little tighter to stop it from leaking some fluid.
- clean up the mess.
- reconnect the negative terminal of the battery and turn ignition to position 2. You should hear the pump fire up and fill the accumulator for around 10 seconds, possibly more.
- Start the engine. all warning lights should go off. test the pedal - there should be no warning lights on. Go for a drive. Check the brakes work! Mine worked much better with the new accumulator. The old one had obviously been on the way out for a year or more.
- and finally park up and check the accumulator for any leaks.

It's actually a really straightforward job, you just have to take your time and ensure that the brake fluid is depressurised before removing the accumulator. You shouldn't even have to top up the fluid afterwards. I guess a bleed of the brakes/fluid renewal would be advisable, but not necessary.

I hope this helps to keep a few more older 480s on the road!
1992 Paris Blue 480 ES

balto8
Knows an Aerodeck isn't a 480
Posts: 221
Joined: Tue Jul 22, 2014 3:02 pm

Re: Teves mk2 ABS - Hydraulic Accumulator Replacement

Post by balto8 » Tue Nov 08, 2016 6:06 pm

That's precious information.

I have that ABS system and got exactly the same symptoms whe I bought the car. I assumed the whole ABS unit was broken so I bought and replaced the whole unit. ONly to find out that the ! and ABS warnings on the dashboard ddin't go off after spending over 250 euros.

Then I read somewhere else that I shoudl try and replace the relays. And by doing this the problem got solved instantly.

So I would recomend to replace your relays first and if not working, follow the instructions above.

The Jaguar Classic parts link ( Spanish)

http://www.jaguarclassicparts.com/es/ja ... or-y-bomba
1991 480 Black Turbo
2012 Seat Exeo ST
2013 VW Polo TSI DSG

nicklee
480 Newbie
Posts: 18
Joined: Wed Sep 17, 2008 1:23 am
Location: London

Re: Teves mk2 ABS - Hydraulic Accumulator Replacement

Post by nicklee » Wed Nov 09, 2016 11:04 pm

Nice one - thanks for the link.

And you're quite right. I tried swapping out all my relays before tackling the accumulator, but unfortunately it didn't solve my problem.

always nice to have brakes that work eh ;)
1992 Paris Blue 480 ES

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