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Question Power steering rack vents

I have my '86 944 NA front end up on jack stands to change out worn L & R Steering Knuckles, engine off, wheels off, hubs off. When I manually turn the spindles from stop to stop my rack vents PS fluid through a forward facing hole at the end of a boss just inboard of the left boot.

Is this normal? Did just expel trapped fluid? Did this blow an internal seal?

Started the engine, turned numerous times stop to stop and only got a few drips, possibly residual fluid from the previous venting. Seems like if a seal ruptured it would really leak with the pump on.

Anyone know what I am talking about? Would you explain it to me?
Old 07-19-2019, 06:18 PM
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There should be a balance tube that passes air from side to side when turning. If the tube is missing, debris ingestion through the hole would make a shorter life of the seal. The tubing does shrink over time and they can pull themselves out but there should be a zip tie around the rack to hold it on.

There is also a spot for the centering device/pointed bolt, that should have a plastic plug.
Old 07-19-2019, 06:50 PM
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I will post a photo tomorrow of where the fluid came out. I will also look for a good illustration of a rack to see if a tube is missing from this location.
Old 07-19-2019, 08:57 PM
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Here is a photo of the rack showing where the fluid is coming out when the engine is off and the spindles are moved from stop to stop. As I said before, there is no leakage when the engine is on and the steering system is pressurized. Is this normal?

Old 07-20-2019, 12:33 PM
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It looks like the tube thomasryan was talking about is missing on your rack. See the pic below, it's the black tube that runs side to side. That will squirt fluid if it's missing.

Old 07-20-2019, 01:07 PM
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Thank you so much! This makes sense to me. The car is relatively new to me and I am trying to bring it up to standard. My intent is to autox this car and I can't have any leaks.

Does this tube just press in? Probably will have to buy a used rack unless someone comes up with a better idea.
Old 07-20-2019, 01:13 PM
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Looks like it just presses in. You can (thankfully) buy it separately and it's inexpensive. Part number 944.347.311.00.

Buy it here: https://www.pelicanparts.com/More_Info/94434731100.htm?pn=944-347-311-00-OEM
Old 07-20-2019, 01:25 PM
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Quote:
Originally Posted by drkshdw View Post
It looks like the tube thomasryan was talking about is missing on your rack. See the pic below, it's the black tube that runs side to side. That will squirt fluid if it's missing.

Fluid shouldn’t be squirting out of there even with that pipe missing, all that pipe does is compensate for the air pressure, if fluid is squirting out you have a bad seal so wyit check for fluid in the boots. Also that pipe is held in place very loosely as it’s not meant to be dealing with hydraulic pressure and if it is subject to any it is likely to just come loose anyway.
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1986 944 (Street); 1986 944 (Track); 1986 951; 1989 951 (3.0L 8V); 2000 996 Cab.

Last edited by 9FF; 07-20-2019 at 01:51 PM..
Old 07-20-2019, 01:49 PM
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9FF, no fluid leaks here when the engine is running and there is PS pressure, it only leaks fluid with engine off and the spindles are moved stop to stop. I will check the boots,thanks!

Last edited by Harley Monster; 07-20-2019 at 04:28 PM..
Old 07-20-2019, 03:10 PM
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it just moves the air from boot to boot.

since you are new to the car, it might be worth looking at the inner tie rods that attach to the rack. they wear at a similar rate as the outer tie rods (especially when peeps crank the steering wheel when the car is stationary).

the deal is, the inners are staked in so its easier with the rack out. the bright side is, rennbay has a rebuild kit if the rack polishes out. imho, it is a much better option than a flaps rebuild.
Old 07-20-2019, 03:11 PM
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drkshdw, thanks for finding that part for me, I will order it and hope my seals are OK.
Old 07-20-2019, 04:29 PM
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Quote:
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9FF, no fluid leaks here when the engine is running and there is PS pressure, it only leaks fluid with engine off and the spindles are moved stop to stop. I will check the boots,thanks!
Trust me on this one, if it’s leaking with the engine off then one of your seals is definitely toast regardless if it doesn’t appear to leak with the engine running.

Remove the bellows closest to the hole that the leak is coming from and I guarantee you will find fluid inside, btw it’s supposed to be totally dry inside those boots. Replacing that compensating line will not cure your leak.

As I said earlier and thomasryan confirmed that line simply moves air. How it actually does it is, when you steer the bellows on one side compress and the opposite side stretches. They both displace air, one side tries to suck it in and the other tries to expel it. Thing is the bellows are quite well sealed so it’s hard for any air to get sucked in or expelled, and if it was left like that the bellows would eventually simply both collapse.

So Porsche made two holes so they could vent easily, problem with that is the holes could suck in debris and then the seals would fail quickly. So they fitted that “compensating” line between the two venting holes and that resolved everything.

So, my advise fwiw is to remove both bellows and clean everything spotlessly clean inside the bellows and around the seal. Then refit the bellows securely and fit that new compensating line. Hopefully the debris that entered the bellows only caused a small leak at the seal and you can delay the reseal job for later.
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Last edited by 9FF; 07-20-2019 at 05:45 PM..
Old 07-20-2019, 05:37 PM
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Thank you 9FF.
How difficult is it to reseal the rack with a kit? Is it worth the effort or should I just find a good used one?
Old 07-20-2019, 06:49 PM
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Thank you 9FF.
How difficult is it to reseal the rack with a kit? Is it worth the effort or should I just find a good used one?
Depends how technical you are, Iíve done two and didnít find anything too difficult and Iím a home mechanic not a pro, hereís the <procedure>.

Imo itís hit or miss buying a used one, you may get lucky or it may fail quickly, itís a gamble. Unfortunately it seems to be a bit of a gamble buying a rebuilt one too these days, they do come with a warranty but its pretty useless as all the work is in fitting it and whoís to say the replacement under warranty wonít also fail quickly. Itís no fun doing the job three times even if you only paid once for the parts.

I guess what Iím saying is do the job yourself if you feel you are capable and at least youíll know itís been done well and you wonít be relying on others work.
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Old 07-20-2019, 07:00 PM
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I’m a retired hobbyist now, but was a licensed aircraft mechanic and a car hobbyist all my life, if I have a procedure to follow, I can do it. I rebuilt the hydraulic cylinders on my tractor, it can’t be that much different.
Thanks for all the help and advice Mike, it is nice to have such a nice resource.
Old 07-20-2019, 07:50 PM
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