Technical Power Steering Fluid

[Sasha1995]

Hi all,

I'm currently in the process of changing my power steering pipes on my Barchetta and thought in the process it would be good to change the power steering fluid.
1) Could anyone advise what power steering fluid I should be purchasing?
2) Could anyone also advise on best practice for removing power steering fluid? I was just going to syringe it out (swap the lines over - he says as if it will only take a moment lol), top up the power steering and run the pump on and off until the reservoir level stabilises?

Many thanks, Sasha

 

[s130]

I use: (this table is from my parts in stock spreadsheet so ignore the Litres as this is what I have in stock)

Halfords	323068/724930	0.75L	Barchetta		Oil - P.Steering	Halfords Automatic Transmission & Power Steering Fluid DII - 1.0L -Dexron II
Fiat/Tutela	GI/A	0.0L	Barchetta		Oil - P.Steering	Tutela GI/A - 1Ltr - Power Steering Fluid - ATF Dexron II - SAE 10W
Castrol	DEXRON III	0.90L	Barchetta		Oil - P.Steering	Castrol Transmax Dex III Pwr Steering fluid 1.00Ltr

The "B" requires 1.0L or 0.9kg of fluid.

Method 1.
Syphon out from reservoir. Refill and then move steering from full lock to full lock with engine running. When on each full lock force a little more (you will hear a groan and rushing fluid) release and repeat a few times. The system is designed to self bleed on full lock operations.

Method 2.
Same as one but only 30% fill or just enough to give a small fluid head in the reservoir. Do the lock to lock etc. and then do all of Method 1 again. This two stage helps remove/dilute the fluid that remains in the system if you are not completely draining via the pipes.

Personally on all cars I've had I just do Method 1 every 5 Years. If you are fussy then every 2 years along with the brake fluids.

 

[StevePD]

I see in the manual it lists the fluid as: Tutela G1/A

 

[StevePD]

S130 beat me to it with a far more comprehensive answe.

 

[Sasha1995]

Halfords Automatic Transmission & Power Steering Fluid DII - 1.0L -Dexron II

Thank you all for your helpfulness and informative response as always!

 

[s130]

I see in the manual it lists the fluid as: Tutela G1/A

Would add that DEXRON III is supposedly backward compatible and an upgrade to DEXRON II

Now what I'm looking for is a lifetime replacement brake fluid. DEXRON came to mind as it is a hydraulic fluid but it's boiling point may be an issue.

 

[Yellofrankcar]

I use Motul Dexron III which has a similar viscosity to the original "Tutela G1/A".

s130: why you're looking for a lifetime replacement fluid?
Assuming it's ment as a joke (the hygroscopic properties of brake fluid also ensure that moisture is absorbed into the brake fluid and the brake calipers / pistons and as a result do not oxidize on the inside -seize-).

Have a nice evening,

Frank

 

[s130]

I use Motul Dexron III which has a similar viscosity to the original "Tutela G1/A".

s130: why you're looking for a lifetime replacement fluid?
Assuming it's ment as a joke (the hygroscopic properties of brake fluid also ensure that moisture is absorbed into the brake fluid and the brake calipers / pistons and as a result do not oxidize on the inside -seize-).

Have a nice evening,

Frank

Interesting thought. I assume that you mean that the fluid being hydroscopic (which it is) will absorb and water present and this will be diluted into the brake fluid as opposed to say a pool of water just sitting there. So for exposed surfaces you either have 100% water or x% water / y% brake fluid.

If the "fluid" is not hydroscopic and the system clean and dry when filled then air/water vapour should not get in the the first place.

Clearly I need to do a little more research on this when I get time. Brake fluid is formulated for the job it does and unlike other hydraulic fluids has to have very very high boiling point so is it this required property that leads to the fluid becoming hydroscopic?

I guess in another x years all braking in modern cars will be 100% regenerative and able to lock and release like modern ABS systems.

 

[Wiltshire Chris]

From memory the hygroscopic properties of brake fluid led Citroen to mineral oils, initially LHS and LHM. The system as in the original DS runs the brakes, power steering, gear change and suspension.

Hydropneumatic Suspension - LHS Versus LHM | LHS LHM

 

[chris3234]

Interesting thought. I assume that you mean that the fluid being hydroscopic (which it is) will absorb and water present and this will be diluted into the brake fluid as opposed to say a pool of water just sitting there. So for exposed surfaces you either have 100% water or x% water / y% brake fluid.

If the "fluid" is not hydroscopic and the system clean and dry when filled then air/water vapour should not get in the the first place.

Clearly I need to do a little more research on this when I get time. Brake fluid is formulated for the job it does and unlike other hydraulic fluids has to have very very high boiling point so is it this required property that leads to the fluid becoming hydroscopic?

I guess in another x years all braking in modern cars will be 100% regenerative and able to lock and release like modern ABS systems.

Unless you have a motor per wheel Regen braking won't work like abs

 

[s130]

Unless you have a motor per wheel Regen braking won't work like abs

And motor/regen per wheel is where I suspect manufacturers will go, or at least a front/back with limited diff. configuration.

A say 200 HP electric motor would be massive. 4 x 50 HP would be far more feasible, better on weight, better on overall control and efficiency, and other ??? factors.

 

[chris3234]

And motor/regen per wheel is where I suspect manufacturers will go, or at least a front/back with limited diff. configuration.

A say 200 HP electric motor would be massive. 4 x 50 HP would be far more feasible, better on weight, better on overall control and efficiency, and other ??? factors.

Not not really
4 motor would be more expensive less practical and less relaiable


As for size Tesla manage fine with two and apperntly the model s has around 520hp

 

[Yellofrankcar]

Hi,

Moisture will always get in the braking system (vapour), this a.o. as result of condensation: the hot air will contain a relative lot of moisture (braking system can get very hot as you know) and the moment that the system cools down you have your moisture.
In theory the system starts without any moisture but in time it will diffuse in the system, the seals (pistons of master and calipers) are not 100% gas tight, thicker substances like brake fluid will stay in but water vapor will slowly intrude the system through seals, brake lines and brake fluid reservoir.
In the end of the seventies I used the then quite expensive DOT 5 brake fluid (silicone based) in my motorcycles braking systems hoping not to have to change the fluid every 2 years and also because it was much easier on my painted wheels (bleeding the system).
I noticed after 4 years that a small amount of water had accumulated at the bottom of the calipers and started to corrode them on the inside, so I did a rebuild and used the DOT 3/4/5.1 ever since.
So the fact that the glycol based brake fluids are hygroscopic is both a blessing and a curse: yes it attract moisture but at the same time this property prevents the moisture from boiling and corroding the brake lines and calipers (it's not for nothing that silicone brake fluid is banned from racing cars - vapour lock).
Just changing the brake fluid every 2 years or so (in principle, the moisture percentage should remain below 3% but good measuring equipment is somewhat expensive for a privat person).
Also glycol based brake fluid is the least compressible of most fluids (although at 200 Celsius about 4 times as much as at 20 Celsius).

Frank