Leakage from top of Hydraulic reservoir? & (!) light??

**SilverSquirrel** · 22 July 2006, 15:05

dude, you might have overfilled the hydraulic fluid? When the car is shut off, a check valve in the bomb might be leaking, and the fluid backs into the resevoir. Check the fluid level with the car off, and step on the brake a few times. then when you start the car, does the level go down a bit?

as for the light, might be just the pressure switch in the servo, or the pump getting tired. The light comes on if the pressure goes below a certain psi, but enough to still give assist. I am no expert. just another idiot with an old audi, a driveway, and some tools. I cant help with the hose location. We drive on the other side of the road over here, but the return come out of the top of the servo cylinder (the one closest to the front of the car,) and goes to a tee with the returns from the bomb and the steering rack, and then off to the reservoie.
Josh

**~~Corey~~** · 22 July 2006, 15:32

Check the pressure switch on the servo, discharge the pressure in the accumaltor (20-30 pumps of the brake pedal, the car not running!!!). Pull the connectors off the switch and make sure the contact is closed, 0 ohms reading if you get infinity then the switch is ******ed and a new one required.

**s2dude** · 22 July 2006, 18:14

Originally posted by Corey

Check the pressure switch on the servo, discharge the pressure in the accumaltor (20-30 pumps of the brake pedal, the car not running!!!). Pull the connectors off the switch and make sure the contact is closed, 0 ohms reading if you get infinity then the switch is ******ed and a new one required.

Thanks guys

Silversquirrel...

Hydraulic fluid level is correct I think......and Bomb is brand new!! Positive its not faulty....
Also the PAS pump is only 2 years old siince it was replaced by previous owner!!
ALl fluid has been flushed and filled with correct G12. Im hoping it is the servo pressure switch now!!

@ Corey

Thanks mate...

I will test the servo presssure switch right about now

When you say make sure the contact is clsoed can you elaborate slightly please! And is 0 ohms the correct reading?
Cheers

**SilverSquirrel** · 22 July 2006, 21:50

Hope your bomb is ok. I hate it when a new part is faulty. Makes for UGLY trouble shooting! I once had an 82 scirocco with a bad oil pump. I put in a shiny new oil pump, fired her up, and she blew out the oil filter and oiled my driveway with about 4 quarts of castrol. After nearly blowing my brains out diagnosing the thing, i had a new oil pump with a faulty relief valve! If the bomb was a reman. it could have a pressure relief valve stuck open, or a weak spring?

If its the switch, great. Otherwise, time to borrow a pressure gauge. The bently manual for the 90 has the procedure, for the 7a cars. Hydro system is the same for s2. Once youve got the gauge, you check bomb, pump, servo, etc... just low enough pressure to trigger the light, but still give good assist? curios to see how it works out! -Josh

**s2dude** · 22 July 2006, 23:42

Originally posted by SilverSquirrel

Hope your bomb is ok. I hate it when a new part is faulty. Makes for UGLY trouble shooting! I once had an 82 scirocco with a bad oil pump. I put in a shiny new oil pump, fired her up, and she blew out the oil filter and oiled my driveway with about 4 quarts of castrol. After nearly blowing my brains out diagnosing the thing, i had a new oil pump with a faulty relief valve! If the bomb was a reman. it could have a pressure relief valve stuck open, or a weak spring?

If its the switch, great. Otherwise, time to borrow a pressure gauge. The bently manual for the 90 has the procedure, for the 7a cars. Hydro system is the same for s2. Once youve got the gauge, you check bomb, pump, servo, etc... just low enough pressure to trigger the light, but still give good assist? curios to see how it works out! -Josh

Thanks Josh....

But I need some info on where this Servo pressure switch is please

I cannot see any connector on the servo...only several pairs of connectors nearby.....Corey?

Can someone please tell me where the hell this switch is so I can get it replaced

Also...do I just multimeter across the switch with the bomb depressurised yes??

Im sure it will be located the same place in relation to the servo on LHD and RHD?? hopefully!!

@ josh.... Im sure the bomb must be ok...It took 43 presses to depressurise it!!! and its not a reman.....
Its a GENUINE Audi bomb

with the cost associated with this!!

TIA

**s2dude** · 23 July 2006, 00:33

Any ideas?

**SilverSquirrel** · 23 July 2006, 03:04

the bomb. note: pressure relief valve.

Attached Files

bomb.jpg (142.6 KB, 164 views)

**SilverSquirrel** · 23 July 2006, 03:07

servo with pressure switch. Note: this is from audi service training on the CQ hyraulic system. Ive never seen the s2 setup in person.

Attached Files

servo.jpg (124.3 KB, 169 views)

**SilverSquirrel** · 23 July 2006, 03:22

Oh... one easy test to do. with the car running and light on, remove the wires to the pressure switch (assuming you found it by now

) The light should go out. if not, the wiring from switch to dash is shorted.

**s2dude** · 23 July 2006, 12:12

Originally posted by SilverSquirrel

Oh... one easy test to do. with the car running and light on, remove the wires to the pressure switch (assuming you found it by now

) The light should go out. if not, the wiring from switch to dash is shorted.

Cheers Josh and thanks for the diagrams

Reason its hard to find it on RHD car is because the servo is in a major PITA position

LHD car servo is a piece of cake by all acounts

**SilverSquirrel** · 23 July 2006, 17:02

**s2dude** · 23 July 2006, 17:12

ok....managed to get to the switch after some severe knuckle skin loss....

It appears the switch is ok and the wiring may be ******ed

I tested the switch and although it was fussy where the probes were (intermittent reading) I got a resistance across the switch once I had cleaned the contacts up...

Turned ignition on with no switch and BINGO!!! NO check light and an OK message when I pressed the brake!!!

But I reconnected it and the constant (!) is back....

SO Im thinking it must be a short in the wiring between the connectors and the ECU.......

Anyone got a wiring diagram for this by any chance????!!!

I cant find one anywhere...

Cheers

**SilverSquirrel** · 23 July 2006, 21:19

DUDE! with the engine running and switch disconnected, the computer thinks the switch is open (good pressure), and the light goes out. This means the wiring is GOOD.

The pressure switch is normally closed (0 ohms with 0 pressure; infinite ohms only if adequate pressure, )

i dont have wiring diagrams for any s2 years, but in the CQ wiring diagram, the pressure switch is wired in parallel to the hydraulic resevoir level switch, so either switch (low pressure, or low fluid level) will throw a light.

My Bentley says the pressure switch opens at 1200-1800 psi, so you could still have decent pressure for braking and steering, but just not quite enough to open that switch?

Normal pressure, according to Bentley, is just over 2000 psi.

So what is that RHD servo buried under? some of that turbo stuff?

Josh

**s2dude** · 24 July 2006, 00:23

Originally posted by SilverSquirrel

DUDE! with the engine running and switch disconnected, the computer thinks the switch is open (good pressure), and the light goes out. This means the wiring is GOOD.

The pressure switch is normally closed (0 ohms with 0 pressure; infinite ohms only if adequate pressure, )

i dont have wiring diagrams for any s2 years, but in the CQ wiring diagram, the pressure switch is wired in parallel to the hydraulic resevoir level switch, so either switch (low pressure, or low fluid level) will throw a light.

My Bentley says the pressure switch opens at 1200-1800 psi, so you could still have decent pressure for braking and steering, but just not quite enough to open that switch?

Normal pressure, according to Bentley, is just over 2000 psi.

So what is that RHD servo buried under? some of that turbo stuff?

Josh

My bad

My brain is stlll hungover from last night!!
ok. SO if the wirings good (though I did not start the car...only turned the ignition on...and the switch "seemed" to test out ok

Corey said that 0 ohms was ok...and infinite means the switch is bad?? From your comment what should the reading have been for a healthy switch please?

THe readings I was getting were not constant which is what I expected (eg// it went from infinite sometimes to 10 - 200 ohms when I pushed/moved the probes on their relative contacts a bit!!). But I cant decide if this means the switch might be dodgy or just as it was so awkward to get the probes down there in effect...blind.

Do you think its worth replacing the switch and seeing if this cures it? (as long as they are not too pricey

) because it seems that you think the servo may be at fault?? or am I wrong here?

The servo on the RHD car is totally buried underneath the dash with little to no room to get your hands in (certainly not a spanner) and also not much visibility!!!

I really want to do the servo test but just getting to the return line is going to be a real PITA!!

Thanks for all your help silversquirrel

Leakage from top of Hydraulic reservoir? & (!) light??

Leakage from top of Hydraulic reservoir? & (!) light??

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