I just collected my 1994 940GL back from the shop which reconditioned the steering rack (a Cam gears unit) by fitting new seals, pinion bearing etc . The service guy warned me that although they had bled the rack , air was trapped in it, and that would account for the pulsations when using steering at low speed, but that it should go away in a week or two. He also made the worrying comment that sometimes because of the new tight rack seals, the power steering pump may fail after a rack is reconditioned.

I asked him if this air entrapment problem was usual, and he replied that he often had this problem with this type of rack, and also one used on Subarus.

The steering wheel does indeed pulse and there is a funny noise when turns at low speed are made, such as getting into a parking space etc.

Should the rack bleed itself of air over time as the service tech suggests ? Could any possible harm be done to either it or the power steering pump in the meantime ?

Is it possible to 100% bleed the Cam gears rack of air effectively, or is there always some bedding in period where air is released, as the service tech seems to suggest ?

I've read the FAQ about bleeding the rack of air, and am contemplating doing this over the weekend. I assume that the tie rod end removal the procedure recommends is so that the rack can be taken fully to the very limit of its travel to help purge air.

Any help / advice appreciated.

John

1994 945 GL, Cam gears rack

even if you put it in the air and rock the wheels back and forth, you may still feel it. the best way to bleed a rack is to modify a ps cap with a nipple in the top. apply a vacuum to it and that should bring all the air out of the fluid. i used to steer 'em back and forth with the engine off, then at idle and still had the conditions you have. good luck, chuck.

Thanks for the advice Chuck. What's the easiest way to generate a sustained vacuum ? I assume that too much vacuum would cause the fluid to be sucked up, so there must be an optimum amount... ?

John M
1994 940GL

use a vacuum gun, like a mighty vac. just pull a vacuum with it. it may take a coupla times. doubt you'll pull any fluid. good luck, chuck.

I've never done a rack on a volvo, but any other rack I've done only requires you turn the wheel lock to lock several times to get all the air out.
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'93 945 turbo. A big comfy box.... and a '90 Mazda 626 GT turbo, 16psi on upgraded turbo and a bunch of other mods.

The vacuum bleed of PS is standard now on some Fords, not that Volvos are not (he heh), in my opinion it indicates poor design, but that is what they say to do. You might be able to use a valve section from a bike inner tube to get something to suck through.