Power Steering Pump 'O' rings

Posted: Sun Jun 06, 2004 11:53 am

(94 - 16v)
I came out of work last Thursday and the power steering pump had dropped most of its fluid due to a blown 'O' ring (one of the large cross headed screw seals).

After reading other posts on this subject I know Audi don't supply them in the overhaul kit, so I got a new 'O' ring from work which was a very close replacement (slightly thicker).

I put the pump back on the car and it seemed to be fine, a few small test drives around town proved this.

Yesterday I did a 80 mile round journey. During which time it's blew/ split/shredded the replacement 'O' ring.

Does anyone know the exact size of this seal and/or what could cause this seal to fail - overpressuring the pump??

Site Moderator Joined: Jan 31, 2003 Posts: 9144

often the high pressure problem is a faulty bomb. Does your car have ABS ?

Posted: Sun Jun 06, 2004 3:42 pm

Yes it does have ABS and a bomb.

How can I tell if it is this overpressuring, and any idea how much a new / recon unit is?

Site Moderator Joined: Jan 31, 2003 Posts: 9144

Testing is difficult due to the high pressures involved. 2000 bar requires special equipment.

Bombs are expensive. Best bet is vagparts.com for a price.

You may be able to remove the bomb and have it checked out by a Citroen hydraulics specialist. The spheres in the suspension on Citroen Xanta and XM models are very similar to the bomb on the Audi

UltraUser Joined: Jan 21, 2003 Posts: 4230

And a damn sight cheaper too! Evil or Very Mad

Posted: Sun Jun 06, 2004 11:14 pm

There is a bypass valve inside the bomb that vents the pump back to the reservoir once the bomb is fully charged. I guess if this valve failed in the closed position it might cause the pump to overpressure and burst the O ring. I would have thought it was more likely to stick or fail in the open position however. This will leak the pressure away rapidly after you shut down the engine, and the warning light will blink on restart every time.

Perhaps another new O ring is called for, making sure its seated correctly. It needs to be a perfect fit really at those sorts of pressures. I would then do the usual bomb test, seeing how many pumps it can manage with the engine off. (20 to 30 pumps is good)

If the bomb fails this test you need to replace it anyway. If it only manages 2 or 3 pumps, or none at all, I would suspect a ruptured diaphragm inside the bomb, or no gas charge at all.

Darn those bombs are expensive!

Posted: Mon Jun 07, 2004 7:54 am

I had a similar problem with the O ring on my pump.

I put a new one on and it blew this straight out after about 20 miles driving. Made quite a noise from the PAS pump when it happened!

I managed to get the old ring to seal after some abuse with a large screw driver and small hammer. Has been ok up to know touch wood.

Its really annoying that Audi dont offer a new seal as these do seem to fail.

Do you get the brake warning light on in the morning at all??

Posted: Mon Jun 07, 2004 10:11 am

I put a new 'O' ring in yesterday, just to try it as I had another spare seal.
I've done about 30 miles this morning and it seems OK.

As for the warning light, when I first bought the car 2 years ago it used to flash on a morning until I changed pads and discs all round and it's never been again until I lost the fluid the other day.

Will keep you posted, Thanks for all the advice up to now fellas.

Posted: Wed Nov 14, 2012 6:32 pm

BUMP!

And hello again, it's been a while...

I have a leaking screw on my PAS pump. The O-ring is so nipped, brittle, and tashed I can't get the exact size. Got a place along the road from work sells them in all sizes, but does anyone know what exact size it is?

Audi stealer say they dont do seal kits, (tried 026 145 541 & 035 198 049A codes), and VAGparts dont seem to exist anymore?

Posted: Wed Nov 14, 2012 8:35 pm

PART NO 026 145 541 is a plug with the seal fitted, i bought one in the last 12 months from TPS a VAG parts distributor about £4. Are Audi saying they are NLA?

Posted: Thu Nov 15, 2012 7:31 pm

Bloke at Audi said they didnt do pump seal kits at all. Am guessing he just didnt check his system, even though I asked by part number.

Guy at work knows someone who works at the VW dealership though, he ordered me the plug and seal, should get it in the next day or so, £5. Shame I didnt know the O-ring size, couldve been 10p. Plug is fine, cut a cross-drive on to the end of a hardened 3/4 bolt, came out no bother.

Leak worse, tried replacing the buggered o-ring with a gasket and some thread tape. Pump very noisy by the time I got home, and oil everywhere.

Car-sharing tomorrow I think. Smug wife and Corsa Sad

Site Moderator Joined: Jan 31, 2003 Posts: 9144

When you install the new o-ring it needs to be soaked in hydraulic oil first. Very easily damaged otherwise

Posted: Thu Nov 22, 2012 5:32 pm

Did it last night after the part eventually arrived, could only get 40 Nm on the screw, not the 60 I saw recommended somewhere here, but it seemed pretty damn tight. Oiled the ring 1st, ta for the reminder.
Will leave the belt covers off for a day or two to make sure theres nothing else leaking, steam cleaned everything today, seems fine so far.
Aux belt pretty sticky after all the oil leaking, next on my list I reckon...