PAS pump strip down How to

[Graham]

22)The 2 plugs which can be seen in photo below (On top, either end of the cast) will house a ball bearing check valve underneath so each pistons discharge will be trapped in the outlet (small banjo fitting which bolts onto the port on top of the pump in picture in the first step) which leads to the bomb. As it is not my pump I did not want to put heat into the main cast of the body, and snapped 2 Alan keys and twisted one.

[Graham]

23)The housing on this pump (where the cam sits) was 23.32mm deep. There is 2 thrust washers/shims one 0.98mm, other 1.00mm. The widest part of the cam is 12.96 wide, and the spigot on the low pressure was 7.75mm proud. So the cam and thrust washers were 14.94mm plus the spigot which was 7.75 makes a 22.69. And the casing is 23.32 leaving 0.63mm of float in the shaft. So with clearance for expansion the new washers (which can be either cast steel or phosphor bronze) need to be no more than 1.25mm. This size will give 0.11mm of float (0.0028”). PLEASE TAKE NOTE YOUR HOUSING DIMENSIONS COULD BE DIFFERENT PLEASE CHECK YOUR OWN SIZES. Thrust washer dimensions were: 15mm(Inboard washer)16mm(Outboard washer) ID and 27.75 OD by 1.25 wide.

[Graham]

24)Inspect the gland bearing for damage (there should be none) this is the metal sleeve inside the housing between the cam and the gland seal. Spin the shaft and wobble it about inside to see if there is play, if so I suspect a decent machinist could bore it out and press in a new one out of brass or white metal (preferable).
24) Using a suitable size socket press in the new gland seal. This can be done easily using a vice but don’t squeeze it too hard, as it might not seal if you crush it.
25)Reassemble the shaft components (Brass and steel ring) with the new front thrust washer and slide it back into the housing through the new seal.
26)I advise now that you re-fit the 2 pumps together with a new o-ring between the faces and the second thrust washer on the shaft. This just makes the shaft secure, and the unit easier to grip in a vice. (Using soft jaws of course).
27)Now slide in the pistons the same way they came out, re-fit the new o-rings (B.S. 016 I believe) ensuring that they sit in the groove, and oil/grease the o-ring so it doesn’t snag on the plug.
28)Refit the spring and spring guide then refit the plug and if the o-ring is the correct size the plug should seal with just a spanner and bit of strip in the cross head, there should be no need to re tighten using an impact screwdriver.
29)Apply anti scuffing paste, (or copper slip will do) to the shaft end where the coupling sits and heat up the coupling to 160-200 ˚C, using either an oven or a gentle flame (No Oxygen, just gas).
30)Once hot using heat mits (or riggers gloves, if your quick) re-slide the coupling/hub onto the shaft making sure it is the right way around and that the end of the coupling/hub is flush with the end of the shaft. Make sure you hold it in place till it nips on the shaft-this should only take up to 10 seconds.
31)Once nipped quickly apply an air supply to the shaft between the coupling/hub and cool the shaft to avoid putting un-necessary heat into the seal possibly damaging it. Try to avoid quenching it in water, if possible submerse the coupling/hub shaft and seal in a heavy mineral oil which will cool it slowly but prevent damage to the seal. It will smoke as you submerse it but this is the best quick way of achieving a good cool rate without damaging anything. Leave it for 5 minutes.
32)Re-bolt the pump bracket and re-bolt on the pulley and the unit should now be ready for use, or if storing the pump, fill it with oil and seal the ports with red caps. I also advise that you put some fresh oil into the inlet port and spin the pump by hand to work it through.

Pro’s and cons of this unit

.

The unit is a very good design with few floors, the design was for long life and efficiency, with the spinning shell to reduce wear in the high pressure pump and a double sided action of the vane pump - both sides of the rotor, pump fluid so no side loading should be seen on the rotor, (even though there will be some but minimal) as the loads on either side will cancel each other out. The unit is very serviceable and the only problem I can see with the pump is the use of metal vanes which wear the housing out quicker than bakelite or Teflon. I do not know the working pressure of the low pressure pump so this might explain the use of metal vanes if the pressure is high enough.



I Hope these procedures helps people with pump problems. If in any doubt about doing this task leave it to someone who can do it, these pumps are expensive items and overlooked mistakes could cost you dearly. I wrote these as a guide only from my background as a hydraulics craftsman/engineer. And have tried my best to make the instruction clear, and simple. Any suggestions will be most appreciated, considered and replied with my views and opinions (with reasons).

Graham Tombling

[Baldy]

nicely done graham
you should write haynes manuals

and i was tempted to interupt that post too

[Graham]

A MASSIVE THANKS TO Tekkno300 FOR LOANING ME HIS PUMP WHILE HIS CAR WAS OFF THE ROAD. I WOULD HAVE DONE THIS A LONG TIME AGO AS MY PUMP IS FINE AND I AM A FIRM BELIEVER OF DONT FIX IT IF IT AINT BROKE. THE PUMP I STRIPPED IS NOW IN USE AND WORKS A TREAT.
Graham Tombling

[Graham]

Here is a few more pics i took of the internals:::

[Graham]

This plug is just a blanking plug to fill a drilling which was to gain access to drill the internal ports of the relief valve and doesnt need to be removed. I removed it to see why it was there.

[audiman]

Bloody great write up Graham, i have printed this off to keep with my file of repair instructions. A really technical input mate. I might pull mine aprt for fun now!!

I think the 3B pump is slightly different, but im sure it wont be too unsimilar

[porkkis]

Good write up.

It's no rocket science. BTDT.

[bob69]

Awsome mate, was going to tackle mine (warning still on after i did the plug fix) but the warning light has stopped since i had to have the steering rack replaced - obvious leak!!!

[S2central.net]

How'd I miss this thread before - fantastic job Graham - obviously a 'proper engineer' !

[Graham]

Cheers Paul
There might be one mistake, as i wokred in British steel most gear was aincient and used the BS o-ring size sheet.
Now comparing it i believe the o-ring is metric, about 20mm Id and 3mm cross section.

The post must have degraded over the years as there is a few unknown characters i cant edit back to proper.
Hope it helps
Graham

[Graham]

Jamo how is this pump going? as i think you have the car now? Its been a few years since it was done.

[Pirvu Eugen]

[Jeffer]

Great writeup Graham. I'm needing it very soon. Thanks