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Max is there supposed to be pressure in the lines? (archive)

[ Follow Ups ] [ 7-series (E32) Message Board ] [ Msg. Board FAQ ]

Posted by Henry J on October 11, 2001 at 20:09:20:

In Reply to: PPS - **DON'T** raise the rear of the car!! posted by Max Fretter (NZ 88 735i) on October 11, 2001 at 04:23:47:

When I changed out my accumulators, there was absolutley no pressure. Of course I had the rear end up in the air-both sides, wheels off. Barely had a dribble. Is this an indication of a problem or by raising the rear end, it created a negative pressure in the system and "sucked" the fluid in?
Curious,
Henry
1989 750iL

Sorry - PPS here.

Do NOT raise the rear of the car with the ATF in the system - that'll just suck the ATF-contaminated fluid back into the LAD system, which goes against the whole premise it isn't there yet... I'd only do it with the pressure feed line already disconnected,so you're suking in air and not more contaminant. Just didn't want you having some gung-ho serviceman putting it up on the hoist to check the pipes out & having the whole excercise killed then!!

PPPS - if you do this yourself - safety first... watch out for the pressure, and any residual pressure in the system.

Max


OK, if you're up for the cost then lets try this, stepping back a little:

1) Both are oils OK for the hardware, so no loss-of-lubrication damage should have been done.
2) You only topped off the cannister, right?
3) You've got no LAD suspension leaks at the rear, right? So I'm thinking the suspension accumulators, valves & shocks should hopefully NOT have yet seen any ATF..
4) The 740 has vacuum brake boost so the fluid only does the power-steering & the LAD shocks, so that's one less thing to worry about.

The can of Pentosin 7.1 I've got here (and I don't need it! but forked out before checking) makes note of the oil being a stabilized oil and they specifically note its use for SUSPENISION UNITS. I'm guessing this is the specific need for the LAD-equipped models - it stands up to use in the shocks; let's face it - the shocks are a one-way trip for the fluid, so it's got to be good for their life - no thinning, cavitation, foaming etc.

If that's a valid starting point, then if the ATF hasn't gotten passed back down the rear of the car (and again hopefully it's not that likely, we're talking about the whole volume of the pipes from the pump to the valve/accumulators). I'd personally suggest flushing out the front - cannister, pump, steering box, hoses - and the lines to the rear, and maybe the accumulators back there too. This should hopefully remove all the ATF... I'd leave the seals be, let's face it - why buy trouble just yet? The ATF hasn't been in long, and isn't 100% concentration - and a seal failure (hopefully) should be gradual, so you can deal with it if it arises, right?

Hope this helps - can't really suggest much more from here, you need to either proceed with the flush or sort out someone to do it (and follow your instructions here, and not get "inventive").

Max


This was done by me before I found this board. It was about 9 days ago. Can I replace the seals myself?






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