740 Power Steering

[Laird Scooby]

Originally Posted by NI_Volvo_Nut

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

I think he might need it after that green stuff!

[panda529e699]

That's good to know. Anyone want a 1Litre can of Pentosin CHF.

But seriously, is it a really bad idea, sounds like it, I checked online and its supposed to be a good option.

I still have some Carlube sythentic ATF left, so with another lot should be able to give the system a good flush through.

[Laird Scooby]

Originally Posted by panda529e699

That's good to know. Anyone want a 1Litre can of Pentosin CHF.

But seriously, is it a really bad idea, sounds like it, I checked online and its supposed to be a good option.

I still have some Carlube sythentic ATF left, so with another lot should be able to give the system a good flush through.

I'd suggest buying a syringe from Amazon or ebay, between 100-250ml capacity and use that as the "turkey baster" to evacuate the old fluid from the PAS reservoir, discharge it into something like an old Pot Noodle pot so you can see the state of the old fluid, top up with ATF-U and then start the car, let it idle and turn the steering to full lock one way slowly, then to full lock the other way slowly and back to centre slowly. Switch off and check the PAS level, topping up and re-bleeding as necessary.
Repeat weekly until the fluid you remove is still clean.

Doing a flushing change where you literally run the engine while the pump shoots the old fluid out as fast as you can fill the reservoir won't get all the dirt out in one go and also, because the new fluid is thicker, dumping it in all at once can cause the pressure to go higher than expected, pushing dirt past the seals and causing leaks. Also because there may be dirt in the pressure relief valve, it may be sticking and a small amount of fresh fluid will help to move this slowly and gently.
Also old fluid will have lost the "Seal-Swell" conditioner that is added allowing the seals to become drier than they should be and hence more brittle. A flusing change can again, cause the pressure to higher and damage a seal.

Doing it in stages by removing the fluid from the reservoir only allows the new fluid to mix and replace the old fluid gradually , minmising this risk. It's also a lot cleaner to do it with a syringe and a lot more economical on fluid as well!

[panda529e699]

I ordered a Sealey TP 696 .5.5 Litre oil and fluid manual extraction pump, from Amazon which arrived today. so once I get some more fluid will give that a try as you recommend. Thanks

[Laird Scooby]

If you've got a litre or more of ATF-U, you'd be good to try it now.