The hoses on the power steering reservoir tend to "sweat" after many years in service. The ATF is a kind of oil that makes the hose cracky and oil seeps through. Also the clamps on the reservoir are not the best. The clamps on the reservoir are screw on, so that bit is easy. The clamps on the pipes (other end of the hose) are pressed on. So that takes a dremel or similar to cut off.

The next you need to know is the  power steering return line hose diameter. Here is a discussion about the correct size.


1992 928 GTS midnight blue

The Netherlands


Anybody for sure know the i.d. of the power steering return hose from the "cooler" loop to the reservoir? My memory says the SAE hose I installed when I refurbished the lines is 1/2 i.d which would be a 12mm i.d. hose.

I am going to source some metric hose and see if it will last longer at the reservoir connection than the SAE hose I seem to only be able to get 2 years out of before the the return hose end on the reservoir starts leaking fluid.


1990 S4
You need another reservoir to pump return line and cut a suitable section from that and it works perfectly - $15.75. Correct size and correct type of hose. Two clamps and you are good to go.

1/2 inch ID is too big, I installed one on my car too and it leaked. I had to tighten the crap out of it, which causes the clamp to cut into the line. The original one may be a 10mm ID line. If someone has the original hose to measure the ID that would be great.
The PS lines are 10mm ID. Not only does Imperial hose not seal properly on a metric tube, it fits so loose that it always falls off or slips off, which is a pain if you have to put hoses on to something you won't be able to access easily once installed. The charcoal cannister for example.


The info above is incorrect for a car starting MY 1985 up to MY 1995. The hose from the reservoir towards the pump (part number 928.347.445.06) is a pre-formed hose like this:

Notice the ID 15mm side at the reservoir and ID 12mm side at the pump. The reservoir shows the same obvious difference.

The hose from the return line towards the reservoir is a ID 12mm hose and needs to be cut (Dremel) from the cooling pipe to be replaced. This is a generic 12mm oil/fuel hose. The type of hose should be chosen wisely as ATF tends to seep through. Nitril rubber is a good choice. It is also good for fuel barrier. See this line for chemical aspects of the hoses: ChemicalResistanceRatingsforGatesHose.pdf

Here is a picture of the two hoses and a ruler to show length. The 12mm-15mm (ID) hose can best be purchased form Porsche. It is not even very expensive. The 12mm short one is a generic one and makes a 90 degree turn towards the reservoir without a problem.


As said before: use a dremel with cutter disk to reach the clamp that holds the short hose to the cooling pipes of the steering fluid. You will see when you're done when the rubber starts to smoke :) Fitting the curved 12-15mm hose (12mm towards the pump) can be done without removing the alternator. But you need some skill and small hands. The ATF will pour out so use a plastic bag to cover the alternator. A long screw driver should be able to undo the hose clamp.




1992 928 GTS Midnight Blue