How does having air in your hydro suspension affect it?
Thanks

the manuals say that the system needs to be evacuated before refilling so I'd be thinking it would - something to do with the compression rates of fuild verus air?

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'62 Morris 850 (Marion)
'65 Mini Delux - sleeper 1275/S discs (Ms Plum)
'69 Vanden Plas Princess 1300
'71 Wolseley 1300
'74 Austin 1300 Countryman
'94 XJ6 Sport 3.2
'04 Rover 75 CDTi

Air compresses at a different rate to the fluid.

It does need to be evactuated just like the manual says if you ask me. I am going through this process now.

Make sure all your seals/rubber are good before you re-presurise - people tell me that they can blow - but I am not sure myself

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Spritey!
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Lower your standards. Increase your success rate.

It's more that the air compresses, where fluid absolutely will not compress. The hydro will be all spongy and will bottom out. I did pressurise the system to get the car to a hydro pump. It only kinda helped a very little.

I think it's the Doc that says that if you can't evacuate the system, pressurise it first, and then let it blow out three or so times. It will purge the air out of the system as the air gathers in the high points of the system.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

In the good old BMC days many service places couldn't be bothered evacuating them for routine pumpups. it's really only necessary if pipes or bags have been changed and air has got in.
Even then, they often used to just pump them high, then let fluid out FAST by depressing the valve. The pressure in the front bag will displace most air out the rear. Then pump up again.

Morris 1100 setup was better, they put the drain/fill valves on the front hoses, near the top of the plumbing. Easier to get air out (it's always in the top of the system).

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.