Hdi xantia s2 PAS pipe nightmares TAKING NOTE?? PIPE IS NFP!

[citroenxm]

The PAS pipe on mums Hdi rusted through recently resulting in a leak and it was right on the angled pipe right as is comes out of the rubber flexi section.. ok. just broke an s2 that didn't leak.. cleaned the surface rust up clean and tidy.. so proceeded to change them over.. got the old one off and wriggled the replacement in.. all looking good.. coated the pipe with underseal and put the car back together... and to my horror.. leak in exactly the same place.. A piece of rust must have just been stopping it from leaking on the old car..

So this was my last s2 pas pipe for the moment.. so, is there a size enlarger for pipe joining or what's the best solution? was thinking joining the s2 rack feed pipe to an s1 front section.

s2 feed pipe is 4.5mm and s1 is a bit bigger at either 5 or 6mm..

any suggestions? braze the two halfs together???

[CitroJim]

any suggestions? braze the two halfs together???

You could Paul but you'd need to sleeve it. I'd turn up a brass reducer to take account of the differing diameters.

It'll work for sure. That BX pipe I repaired at last year's CXM is still going strong.. That one had an internal sleeve.

The only worry is you don't want to get too much heat too near the rubber bit. To ensure this you need to braze using a very small, hot flame as say, from an oxyacetylene torch...

[citroenxm]

Id use an s1 front section then and join it further along for example above the gearbox or where it runs along the edge of the subframe .. id need to check if the s2 pipe will slide inside the s1 pipe... tightly too.. then possibly seal it up with a braze??

ive never brazed before.. is it like silver soldering with a blow torch??

[CitroJim]

ive never brazed before.. is it like silver soldering with a blow torch??

Yes, basically it is Paul. The secret to a good braze is clinical cleanliness (the surfaces really must be absolutely spotless and utterly free of oil and grease) and a very close fit together as braze will not fill gaps.

Then you need a lot of very precisely directed heat. To braze steel you need the steel glowing red hot. Most blowtorches cannot get it hot enough and have far too big a flame. My Calor propane setup is marginally good enough for small work but fails on anything big.

Oxyacetylene or a mapp gas setup is what you ideally need.

Another way of providing adequate heat is to use a carbon arc attachment on an arc welder. The arc struck between the carbons is hot enough to braze anything but you need to take care using carbons. The arc produces enough UV light to fry any exposed skin and eyes to a crisp.

Once you have the work hot enough, maintain heat and feed in the brazing rod and watch it flow around the joint. It flows under the joint by capillary action and this is crucial to a good joint and why the gap between the two surfaces cannot be large.

[citronut]

apparently you can braze useing a blowtorch with a propane butane mix, obviously also with the correct tip/nozzle to produce a small concentrated flame

[citroenxm]

Going to look at this tomorrow, to see if a Series TWO PAS pipe will fit tightly into a Series One PAS pipe..

In the order of Rack FEED pipe, with "ordinary" brake flare and 4.5mm pipe, and join at the rear along the subframe edge to a Series one "Front half" which I think is 6mm pipe.... Then most of the PAS pipe is coated and should not need attention again. Of course a good coat of under seal shall be applied too..

Report back tomorrow...

[citroenxm]

Right, a bit of progress today..

I found a compete PAS pipe from an 8v Petrol, which has the pump outet in a different position to HDi/TD pumps, so I thought as a try out worth wasting the pipe if it goes wrong.

So I cut the pipe and cleaned the edge out... I was amazed to find the pipe like this:



Thats the end from the pinion valve, however, LOOK at the pipe wall thickness!!!

Its like that right along the pipe to the Rubber section.. The S2 pipe has the same pipe bore, but the wall of the pipe is HALF the size...

So, I got a drill bit and experimented.. and created this:



After cleaning up the S2 pipe up, To my luck and judgement the S2 pipe slid into the S1 pipe I had drilled out, and a PERFECT fit!





looks better in the flesh...

just need some propane to stick them together...

[CitroJim]

Yes, the ends are double thickness Paul, I think you'll find it is two concentric pipes at those points.

What you've done there is good but nowhere near clean enough for brazing.. It needs to shine brightly and be clinical.

And remember loads of heat and don't bring the brazing rod anywhere near until the joint is glowing nice and red

[citroenxm]

So did a bit more on this tonight under cover...

Got the blow lamp going...



and had a go, however, got it sealed, but awfully lumpy and crap.. wasn't happy, tried a bit more.. then the smaller 4.5mm S2 pipe split.. grrrrr...

So cut it down a but, and also the larger 6mm pipe.. but had to re drill the 6mm pipe. I used a 5mm drill thoughtlessly, which of course resulted in a gap between the smaller pipe and larger pipe. I then thought ah, the braze might run down and help seal the pipes better, so pressed on... and eventually got the following..





It looks ok. I blocked off the pump end and blew as hard as I could and it didn't leak.. so it seemed to be sealed. I realise my puff is not as strong as the PAS system, but ive got hope..

Should I re-enforce the join more? Or will it be good enough as it is?

This PAS pipe is now NFP.. so I cannot sugest strongly enough for any S2 owner to CHECK YOUR PAS pipe! I have said this before, but worth the check, the ony other way if you dont want to braze pipes is to swap Pinion Valves on the Rack!

[CitroJim]

It looks OK Paul and as long as you had a good overlap between the pipes and all surfaces were really shiny clean and oil-free you should be fine. No reinforcing needed as long as you had a decent overlap and the gap was not so large as to prevent a good flow of braze right into the joint by capillary action.

Only one way to find out...

Note that you can't re-melt the joint and break it apart to redo it. Brazing is like welding in that you only have once chance at it.

[addo]

AL4 equipped cars, have a union in the PAs line forward and down on the nearside.

It's very handy.

[CitroJim]

AL4 equipped cars, have a union in the PAs line forward and down on the nearside.

It's very handy.

So does the V6 Xantia., Where the PAS pressure regulator is...

[citroenxm]

Ahhhh but the Td auto s2 cars don't.. couple of years ago i was called to an S reg Td xantia estate auto.. I had to fit a complete pipe. the one I took off had rotted but there was no join...

All xantia hdi are manual anyway with no joins.. and most go right on the curve after the rubber link pipe .. so of course there's no room for flaring which is what makes the job SOOOOOOOOOOO much more involved...

[Xaccers]

Yup I have this fun job to look forward to on Juliet

[citroenxm]

She an S2 Xac!?

My next thought was to get 4.5mm pipe (if its available as a coil, and stick a standard Brake flare which is what they have on S2s.. OR, bite the buillet and swap the pinion valve for an S1 valve...