NOT another HP pump question...

Frequently asked technical questions and common modifications/improvements
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cauchoiskev
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NOT another HP pump question...

Post by cauchoiskev » Fri Mar 26, 2010 6:19 pm

an HP pump answer :) . Partial answer anway.

Dunno if you are like me, but nothing attracts me more than totally pointless challenges. Particularly if I've got plenty of other highly useful things to do. I've got a brand new pump on my only BX, so what the hell would I want to be opening the old one up for ?

Well, because it's there, and I've never opened it up before...

As it happens, it's surprisingly easy, and I wish I had tried before shelling out on the new pump.

First off, you need a special extractor tool to get the pulley off.

I used an Aldi fake Dremel, an old jack and two lengths of mild steel bar to make mine :

Image

Into a big vice, and wind away !

Image

The pulley came off with surprising ease :

Image

Next up, following the mad Frenchman's method, I tried whacking the shaft with a big hammer to get the cover off : bad idea. It fattens the end of the shaft, which then sticks in the roller bearing. I would strongly advise making a second extractor tool to get a grip on the casing. In my case, the first tool was luckily easily adaptable :

Image

So out comes the shaft. Be careful not to loose the small bits inside the pistons if they should fall out. Then you might want to get the ball-bearing out, you'll need a drift for this, about 18mm diameter :

Image

Then, to separate the two machined blocks, there are 5 5mm allen screws :

Image

Which gives you this :

Image

Here you can see the wear on the bottom side of the valve disc :

Image

This is what you find inside the pistons :

Image

And here is an overall view of the innards :

Image

The only thing I didn't bother taking out was the needle bearing, it would be simple to drift out :

Image

If your pump is leaking at the pulley end, this is probably the cause :

Image

an o-ring roughly ID 25mm OD 32mm. It would probably be possible to find a replacement.

The big case joint might be more difficult to replace. Silicone might be an answer (it's on the low pressure side of the pump), or at worst, maybe welding the case to the body ?

Conclusion, it is most definitely possible to convert an HP pump from a low-mileage non-PAS petrol-engined car for use in a high-mileage PAS diesel car.

It might even be possible to recondition worn pumps by flipping over the valve discs, any volunteers :) ?

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Post by docchevron » Fri Mar 26, 2010 8:59 pm

Nice work! Great pictures too!
Suspect we'll move this over to the FAQ forum to be immortilised.

I've got about 5 cajillion dead HP pumps, time to pull them apart I think!
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Post by Aerodynamica » Fri Mar 26, 2010 10:07 pm

Excellent work there - any new thoughts on the failure points? piston springs? disk seats etc?
Graeme M

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Post by Defender110 » Fri Mar 26, 2010 11:31 pm

Nice one, many thanks for sharing.

I'm going to have to open a photobucket account and sort this picture posting malarkey out!
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Post by GeZ » Sat Apr 03, 2010 8:24 pm

Excellent!!!! many thanks as my valver after all the systems I've overhauled needs also a new pump in order to have a brand new hydropneumatic system (extremely difficult to find here in greece, I bought one a year ago luckily) so I will use this method for my old pump!!!!

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Re: NOT another HP pump question...

Post by Simon B » Sat Apr 03, 2010 10:33 pm

cauchoiskev wrote:an HP pump answer :) . Partial answer anway.

Conclusion, it is most definitely possible to convert an HP pump from a low-mileage non-PAS petrol-engined car for use in a high-mileage PAS diesel car.

It might even be possible to recondition worn pumps by flipping over the valve discs, any volunteers :) ?
Any thoughts on whether one could move the insides of a new diesel HP pump (still available ?) into the body of a failed petrol HP pump. :-k
Have
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cauchoiskev
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Re: NOT another HP pump question...

Post by cauchoiskev » Sun Apr 04, 2010 11:44 am

Simon B wrote: Any thoughts on whether one could move the insides of a new diesel HP pump (still available ?) into the body of a failed petrol HP pump. :-k
I can see no reason why you can't do diesel->petrol conversions. The reason I mentioned petrol->diesel is that it's far easier to find a low-mileage petrol pump than a diesel one. The whole idea is to avoid having to buy a new pump, but what you mention could certainly be done if you want to.

Forget about new pumps from Citroën : they're about 2000 quid !

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cauchoiskev
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Post by cauchoiskev » Sun Apr 04, 2010 12:02 pm

Aerodynamica wrote:Excellent work there - any new thoughts on the failure points? piston springs? disk seats etc?
No radically new thoughts TBH Graeme. I've never heard of spring failure, only sticking pistons. Possibly fixable, but would it be worth it ?

As for the disc seats, maybe grinding using the unused side of an old valve disc fixed on the end of a dremel with polishing paste ?

Another thing that could be tried would be polishing the pistons and the bores. I have seen a theory on a French forum that micro-scratches are what cause leak-back, rather than simple "wear". The idea seems to be that there is always a small gap between the piston and the bore, even new, which allows lubrication. Scratches break the film of LHM and cause a leakage. Pourquoi pas ? Would be worth a try, I think.

Apart from that, pump failure comes from leakage at the pulley or ball-bearing wear. No mystery there. BTW, I have got the SKF reference for the bearing somewhere, I will look it out.

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NOT another HP pump question...

Post by Muiruri » Sat May 08, 2010 6:06 pm

Feeling inspired by Cauchoiskev I pulled apart one of my failed pumps and ended up with this:-
Image

The disk seats were worn out. I therefore took this piece (below) to a local engineer for skimming. From the grooves arrowed it was a bit tilted after the job. I greased the big bearing on the pulley end in situ. It can easily be removed though. Image

I flipped over the valve discs since one side was worn out, assembled my pump and apprehensively tested it on the bench. It worked! I was feeling on cloud nine!:D I fixed it on the BX and it worked. It is very quiet and efficient.

One can actually recondition an old pump and get away with it.

Regards,

Sammy Muiruri
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Post by Oscar » Sat May 08, 2010 10:09 pm

what a smashing thread - thanks folks.
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Post by rayfenwick » Sat May 08, 2010 11:57 pm

Very good work - I wish I was more mechanically minded - must start practising.
Ray

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Re: NOT another HP pump question...

Post by Odedn » Wed Jan 25, 2017 5:33 pm

Hi,
My pump is leaking badly.
I should replace the seal, probably.
Does anyone have any photos regarding to how dismantle the pump ?
The photos in this thread are no longer link into.
I would appriciate your assitence.
Thanks,

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cauchoiskev
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Re: NOT another HP pump question...

Post by cauchoiskev » Sat Aug 12, 2017 4:39 pm

an HP pump answer :) . Partial answer anway.

Dunno if you are like me, but nothing attracts me more than totally pointless challenges. Particularly if I've got plenty of other highly useful things to do. I've got a brand new pump on my only BX, so what the hell would I want to be opening the old one up for ?

Well, because it's there, and I've never opened it up before...

As it happens, it's surprisingly easy, and I wish I had tried before shelling out on the new pump.

First off, you need a special extractor tool to get the pulley off.

I used an Aldi fake Dremel, an old jack and two lengths of mild steel bar to make mine :
IMG_3595.JPG
Into a big vice, and wind away !
IMG_3597.JPG
The pulley came off with surprising ease :
IMG_3604.JPG
Next up, following the mad Frenchman's method, I tried whacking the shaft with a big hammer to get the cover off : bad idea. It fattens the end of the shaft, which then sticks in the roller bearing. I would strongly advise making a second extractor tool to get a grip on the casing. In my case, the first tool was luckily easily adaptable :
IMG_3610.JPG
So out comes the shaft. Be careful not to loose the small bits inside the pistons if they should fall out. Then you might want to get the ball-bearing out, you'll need a drift for this, about 18mm diameter :
IMG_3615.JPG
Then, to separate the two machined blocks, there are 5 5mm allen screws :
IMG_3617.JPG
Which gives you this :
IMG_3618.JPG
Here you can see the wear on the bottom side of the valve disc :
IMG_3619.JPG
This is what you find inside the pistons :
IMG_3621.JPG
And here is an overall view of the innards :
IMG_3622.JPG
(to be continued...)

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cauchoiskev
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Re: NOT another HP pump question...

Post by cauchoiskev » Sat Aug 12, 2017 4:51 pm

(...continued)

The only thing I didn't bother taking out was the needle bearing, it would be simple to drift out :
IMG_3624.JPG
If your pump is leaking at the pulley end, this is probably the cause :
IMG_3625.JPG
an o-ring roughly ID 25mm OD 32mm. It would probably be possible to find a replacement.

The big case joint might be more difficult to replace. Silicone might be an answer (it's on the low pressure side of the pump), or at worst, maybe welding the case to the body ?

Conclusion, it is most definitely possible to convert an HP pump from a low-mileage non-PAS petrol-engined car for use in a high-mileage PAS diesel car.

It might even be possible to recondition worn pumps by flipping over the valve discs, any volunteers :) ?