I have never seen this on a service schedule...

Should the PAS fluid ever be changed on a regular tintop? Are there filters etc on the pas circuit?

Or is it a system that should be left alone for the life of the car until it stops working?

Garages treat them as sealed for life so 100k miles service interval.

Only costs a few ££ to crack a lower hose, drain down and refill which can save an expensive repair. so that's what I do every few years along with gearbox and axle oils.

Regards Mark

I take it the system is self purging? So any air that gets into the hydraulic lines automatically escapes?

As with all oils they get broken down though use and dirty with metal particles, if you like the car then I’d say change it regularly. I wouldn’t pay to much attention to the manufactures change schedule as they have done that with a limited lifespan. Its always better to change fluids and filters more regularly than recommended.

btw even for my 35 year old JCB digger I change the hydraulic oil (and we're talking a 5 gallon drum of the stuff) every 6 months, hence its still running fine after 35 years...

[Edited on 17/8/09 by Mr Whippy]

Worth doing then... cant imagine it will cost much..

Is there a filter on PAS system?

Is there any risk of airlocks?

Personally I've never seen a PAS system with a engine like oil filter. They use a continuously circulating loop with the reservoir bottle at the end, so it’s self purging. I'd drain it by slacking a hose at the lowest point. Then put the hose on, fill the bottle up to the mark, start the engine and keep topping up till the level is correct. Then turn the steering to both extents to push out any remaining air and check the level again.

there you go a simple how to - linky

and a you tube vid - linky



[Edited on 17/8/09 by Mr Whippy]

My donor didnt have a PAS filter.

Best not to disturb any hoses unions -- has the potential to open a can of worms.

Drain off the fluid with a suction extractor bottle bottle (only few quid off ebay) or a turkey baster only about a quid from Sainsbury.

Be very careful you get the right fluid as some modern PAS systems particularly Volkswagen group use special fluids putting bog standard ATF could lead to replacing the whole system.

The correct way to get out a PAS system is jack both front wheels off the deck and with the engine running turn the steering slowly from lock to lock a few times without the lid on -- important not to hold it on full lock is this pops the pressure relief valve. Having the wheels off the ground reduces the pressure in the system which makes the trapped air pockets bigger and easier to get out the pipe work.


[Edited on 17/8/09 by britishtrident]