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For those who want to clean and rebuild their pushrod operated Pierburg vacuum pump, as described by other threads on here and elsewhere...

The replacement pushrod seal is very hard to find in the UK. Or at least it took me weeks on-and-off of searching. Maybe I used the wrong search terms. Eventually found one listed by maydayseals.co.uk . You're looking for a U-Ring (yes "U"-ring) sized 18 mm x 10 mm x 5.5 mm.

Mayday's stock number is (currently) SU18-10-5.5-P and it's £5 plus £4.50 P&P.

You'll also probably want to change the pump-to-head gasket. The main dealer supplied 075 145 117 C for my '02 2.5TDi . It appears slightly different from the original, but still looks like it will fit. There was a change to the gasket late 1996. Dealer price I paid was about half the best ebay price.

Total cost of parts is less than £20. Apart from that you'll need a T25 Torx, some old rag, an old 15mm socket, and an 11mm socket.

Tips:
  • When compressing the spring, don't put the other end of your compressor on the piston: it's light alloy and others have said they cracked it doing this. Rig something up so the compressor bears against the body of the pump.
  • Grind the end off the 15mm socket so that the 'teeth' are right at the end, not recessed. Then grind the outside down to make a cone. This will engage better into the pushrod's hex end.
  • I welded the modded 15mm socket to the middle of a bar, drilled two holes in the ends of the bar, stood the pump body on a piece of wood with a hole in the middle (to get a socket onto the 11mm nut) then used two threaded fasteners to pull the bar down onto the wood to compress the spring. Sounds complicated but took about 5 minutes to lash it up.
  • When you pull the top off the pump, do it really s-l-o-w-l-y. The gasket tends to stick and you don't want to tear it - replacements are not available. You can use the gaps beside each screw-hole to carefully lever the lid off with a screwdriver.
  • Take photos as you disassemble so you know where each valve goes. Note the valve underneath is held in by the spring and will fall out. Note which way round the old seal goes before you remove it.
  • The piston has a split ring on it which comes off as the piston leaves the bore. Watch out for it. Assembly is much easier than you might think, despite the ring.
  • Lubricate the rod and the piston with a little light oil on reassembly.
  • Others suggest replacing the pushrod. But, let's face it, if the pump didn't fill with oil we wouldn't take it off and so the rod would - like all the other cam followers in the engine - stay there until we fitted a new camshaft. So is it worth it? Is it a good idea to put a new follower on a bedded-in cam anyway? Your call.
Please post your successful (and failed) pump rebuilds here to inform and encourage others...
 

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Discussion Starter #3
Thanks... was just pulling together lots of info from other threads and putting it in one place, together with the supplier info.

Yeah, thought about offering a service. But by the time I priced it to allow for the P&P both ways, the cost of parts, the cost of the occasional failure... I doubt the cost saving I could offer over a new pump would be attractive enough to offset the extended time the customer would have to wait while assorted couriers play van-football with their pump.
 

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Thank for this thread i goingto keep watching this, I'll wait till some photos go up, because I'm as mechanically minded as a ape wearing boxing gloves
 
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