ZF Steering Rack questions

Ok I got the rack off the car, cleaned it and found the following. The
leaking boot (Passenger/RH side) had a few holes, the largest was about
3/8"x1/4" and shaped like a football. I removed that boot and cleaned the
connection of PS fluid common to the rack and tie rod. While removing the
LH boot (good no holes) I noticed a gurgling sound coming from the RH end.
As I squeezed the LH boot fluid was dripping from the RH side, so they are
connected together with the plastic flex hose that is zip-tied to the rack
It connects the main gear housing to just outboard of the last seal inside
the RH housing. Does the plastic hose collect the excess fluid from BOTH
ends and return to system. It's positioned at the 3 o'clock (or horizontal)
position, if it was on the top too much fluid would fill the boot, if on the
bottom it would take all the fluid away.

Do I have a bad rack of just a leak in my RH boot? Some fluid is needed to
keep the tie rod ball joint (common to rack) lubricated and with my boot
hole the plastic return line can't do it's function?

This is not a total waste of time, I am also replacing the upper oil "pan"
seal and the rack needed to be removed. The oil leak was my main concern,
but about a few months ago I started getting fluid coming from the RH boot
area.

If the boot did not have a hole would I have still had a leak? Am I correct
in thinking the plastic (low pressure) line is a return of excess fluid.

 

I don't fully recognise your description of the connections, but here
is my experience of a couple of racks (one a ZF) from some 240s a few
years ago:

Fluid in the tie-rod boot meant that the seals inside the rack were
leaking. There shouldn't be any fluid in the boots beyond a little
added during assembly to lubricate things.

The leak is confirmed by the hole in the boot; this is a classic sign
of leaking seals. The boot fills with fluid and sags under the weight.
When the wheel is turned to full lock, the top of the sagging boot
fouls the tie rod knuckle joint and gets pintched between it and the
rack housing.

There is a pipe between the two boots to enable the squeezed air from
one boot, as you the wheel is turned, to escape to the other side. The
power steering fluid circulates from the pump to the valve housing
(the bit that the steering column connects to) and from there is
diverted to either side of a piston within the rack tube. There are
seals and bearings inside the ends of the tube that should prevent any
fluid escaping.

It is possible the replace the seals and bearings, but I found
sourcing the parts to be a major problem. A rebuilt rack may be the
best option.


--

Stewart Hargrave

I run on beans - laser beans


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