Hobourn Eaton vs ZF power steering pump thread.

[eddy]

I have just bought a replacement pas pump, ANR2157 for my 1998 300tdi.Seems the Hobourn has been replaced with a ZF.When trying to attach the high pressure fitting,it only goes on a couple of turns compared to the full thread on the original,and of course leaks like crazy.Looking at the fittings they look identical but obviously are not.Have been down to the local hydraulic supplier and Enzed....nothing to fit the ZF pump.....could it be SAE?Any way around this dilemma or do I have to buy a compatible hose to steering box,could be QEP105760 or NTC5494?

[Peppercorn]

**** mate, if enzed cant help you you're in a pickle. I'd go to a specialised Bolt shop and get them to identify the threads and work out what you need.

Get those threads identified then, you can work out the fix.

[loanrangie]

I would contact the supplier as see if they can shed any light on it, should be a direct replacement so maybe just the thread needs cleaning up or could be a faulty batch.

[eddy]

I think I will try the local engineering shop.Get them to match the thread of the Hobourn fitting to a tap and run it through the ZF pump.The original ANR3131 hose will then fit.

[eddy]

Running a tap down the thread was not recommended,apparently one was 18tpi and the other 19tpi.Reckon it would leak under high pressure.
Eventually found a company able to offer an alternative solution to the problem.Pirtek in Fremantle ended up cutting the end off the ANR3131 hose and silver soldered a 9/16 male JIC fitting to it,then soldered in a 9/16 female
JIC swivel to the unknown thread of the ZF pump.
So if buying a new 300tdi pas pump from Paddocks in the UK,make sure it has suitable fittings for the original hose.

[eddy]

Another tip is to replace the three mounting bolts with ones that are 20mm long.The ZF pump is all alloy, compared to the cast iron and alloy Hobourn one.
The longer bolts give better security in the alloy ZF pump,as there is greater depth of thread to accommodate them.