This is an expensive little unit. Rod at The Parts Connection (800-517-6060) has ZF rebuilds at a good price. Your car will have one of three different types of pump.
- Early '90 cars (up to around 10/89 build) will use P/N 034 145 165.
- Later '90 cars use P/N 054 145 165 G.
- All '91 cars use P/N 054 145 165 K.
- Remove the 3 hydraulic hoses.
- Remove v-belt pulley.
- Remove old pump and attach new one.
- Reconnect pulley and hydraulic hoses.
- Remove pump from car. You have to remove the plastic air shroud that covers from the front of the car to the top of the radiator, but not the plastic engine compartment-to-radiator shield, which is quite a PITA to remove. Loosen the three hose bolts, loosen the two belt tension adjustment bolts, remove the hose bolts, remove the bolt mounting the brake hose to the rear of the pump, and remove the two bolts connecting the mounting bracket to the block.
- Remove the belt pulley from the front of the pump. You can wrap a used belt around the pulley and put the remaining portion of the belt in a vise, similar to a strap-type pipe wrench. Three socket head set screws are accessible through the pulley. Mark the orientation of the pulley to the mounting flange for reassembly location. You may have to gently tap the pulley off the shaft.
- Remove the two bolts attaching the pump to its mounting bracket.
- Four "small" bolts (probably 6mm) attach the brake booster pump to the front of the steering booster pump. Removing these splits the two pumps apart.
- Four larger bolts (about 8mm) hold the halves of the steering booster pump together.
- Finally, the access plugs for the pistons of the brake booster pump (the large, cross-slotted plugs) can be loosened and removed from the top and bottom of the brake booster pump. A conventional slotted screwdriver is too small to provide decent purchase in the slots. Get an 11/16 inch or 3/4 inch drag-link socket, and then grind down its width to fit into the slot lengthwise.
- You're now at maximum disassembly - unless you want or need to replace the shaft seal on the very front of the brake booster pump. Mine wasn't leaking (fortunately!) so I left it alone. To replace this seal, you need to press the pulley mounting flange off the main shaft, which would require a hydraulic or mechanical press. The shaft could then be removed from the pump, and the seal could be renewed. The flange would then need to be repressed onto the shaft.
- The rebuild kit from Audi consists of about 6 O-rings, one "rubber seal from hell" (RSFH), and one holder for the "rubber seal from hell". Two O-rings seal the access plugs for the pistons of the brake booster pump. One O-ring seals the halves of the steering booster pump. One O-ring seals the brake booster pump to steering booster pump mating surfaces.
- And then there's the RSFH - a very complex, molded rubber seal that seals the working portion of the steering booster pump impeller to the back of its case. STUDY how the old one is laid into the back of the impeller, then *gently* remove (pry) it out of place.
- Clean everything, especially the mating surfaces that are sealed by O-rings.
- The new RSFH and its holder should be positioned on the back of the impeller, and gently pressed into place. The seal has a "top" and "bottom" (i.e., it is asymmetric in cross section), but is symmetric rotationally (i.e., you can't install it 180 degrees out of phase).
- Reassembly is the reverse of the above. I used clean Pentosin as an assembly lubricant.
- Once the pump is bolted back to the engine block, reattach the low pressure supply hose from the Pentosin fluid reservoir. Add Pentosin slowly and rotate the pulley by hand to prime the pump. You're primed once you get fluid out of the steering pump high pressure port.
- Attach remaining hoses, belt, etc.
- Bleed system per Bentley. I needed about 1/2 litre of Pentosin.
Cost: about $40 for the seal kit, $5 for 4 crush washers and 2 O-rings that seal the banjo bolt hose connections, and $9 worth of Pentosin. A lot better than $300 for a rebuilt ZF pump (aftermarket) or $950 for a new pump (Audi).
