740 Power Steering

[panda529e699]

Hello

I was thinking about changing the power steering fluid, I cant find in the manual if this is required or not, just after some advice on it and has anyone done it before.

Thanks

[Forrest]

I’ve done it on a 940 using the “turkey baster” method. You vacuum pump the old fluid out of the reservoir, replace with new, turn the rack from lock to lock a few times and repeat until the fluid is clear.

[Laird Scooby]

It's well worth doing, repeat the above procedure once a week until the fluid stays clean. You'll find all sorts of improvements to the PAS as a result!

[panda529e699]

Thanks for info, I was looking at Pentosin CHF Green fluid, might give that a try and update on how it goes.

[Dirty Rooster]

But wont the original fluid still be (partly) down in the rack,
so you'd end up with a mixture ... or am I wrong?

[Jebus]

Some will but you pump it all the way through the system, and dilute out the old fluid as it all mixes together.

You can get under it drain everything out and refill, but takes longer and you get more messy, flushing with the the turkey baster method is cleaner and easier and ATF is cheap enough to buy the little extra you go through isn't really a worry.

[360beast]

Originally Posted by panda529e699

Thanks for info, I was looking at Pentosin CHF Green fluid, might give that a try and update on how it goes.

CHF fluid is "central hydraulic fluid" we use it at work for Bentley Arnage's ride/height control. I would just stick to good old Dextron III AKA Dex 3.

[Laird Scooby]

Originally Posted by 360beast

CHF fluid is "central hydraulic fluid" we use it at work for Bentley Arnage's ride/height control. I would just stick to good old Dextron III AKA Dex 3.

Each to their own Luke (Dex III ) or Dex II as Volvo specify or my personal favourite, Carlube ATF-U - better than Dex III as it contains different friction modifiers and a better "seal-swell" and certainly gave improved results over Dex II. Have to confess to not trying Dex III but ATF-U is also rated for Volvo/Toyota AW gearbox use including the JWS3309 spec but not some of the later "strange" specs but (importantly for me) is rated as ATF Z-1 Honda spec.


GM would be spinning in their grave calling it Dextron though! No "t" in it!

As you rightly point out about the LHM/CHF, it's a Citroen product designed to operate at stupidly high pressures in specifically designed hydraulic kit and because of the content, could damage the seals etc in the normal PAS system - not worth the risk of trying IMHO!

[panda529e699]

The green fluid is supposed to be better at lower temps ,its also thinner but I get what you mean about the seals. I have already ordered the green one, will see what its like when it arrives.

[NI_Volvo_Nut]

Originally Posted by panda529e699

The green fluid is supposed to be better at lower temps ,its also thinner but I get what you mean about the seals. I have already ordered the green one, will see what its like when it arrives.

I have a spare rack and PAS pump for a 740;-)