Citroen XM Forum

White Exec wrote: ↑

Sat Jun 13, 2020 2:37 pm

Under the regulator pressure relief (depressurising) bolt there should be a ball bearing, which the bolt presses against a seat.
Wonder whether it is still in place? Or damaged/dirty?
There are warnings not to undo the bolt by more than about 1 turn, in case the ball falls out and gets lost.
Unusual to get a leak from just there.

Can post a diagram of the regulator innards, if you need it.

Thanks - I knew about the ball bearing and was careful not to undo the bolt too far. Would the system ever get pressure up if the ball bearing was missing? Is there an O-ring, or some other form of seal on that bolt? When I tighten it, should it reach a point where it is obviously tight? This just seemed to get tighter, without coming to a definite stop. Perhaps that diagram might be helpful

My first thought was that it had to be the return line leaking, and finding that it's held in place by a jubilee clamp with a long tail (ie wrong size) seemed to confirm that. However after tightening the clamp, and thoroughly cleaning the regulator, I'm pretty confident that it is the pressure release bolt.

Since I'm getting a few bits from Eathan, perhaps I should ask him to throw in the regulator. I could overhaul it and have it ready so the car is off the road for the minimum time...

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citroenxm wrote: ↑

Sat Jun 13, 2020 8:19 pm

The V6 pump is unique and must not be mixed with any other engined car as the pump regulator is external to the pump (not system regulator) let's not get mixed up. The pump valve is on the passenger side of the front subframe..

I'm not sure if the 2.5td pumps are the same or not. They are visually but not sure on the valve regulator..

Thanks - that is obviously very important to know! I had got as far as noting that the Xantia pump had a different part number, but had no idea there was such a profound difference.

MIke (Xantia_V6) has already pointed out that the pumps used with the ES9J4 engines in the XM and Xantia have the pulley attached with little bolts. Is it possible that the Xantia V6 also has an external pump regulator?

Cheers

Alec

Yes the Xantia V6 has the same pump and steering regulator as the ES9 XM, but they are just as rare.

The main pressure regulator is similar to other XM and Xantia but beware that the hydraulic fittings changed so not all are interchangeable.

. The 12mm pressure relief bolt is a special, with a thick plain section just below the head.
Normally, the head sits a couple of mm proud of the regulator body, so the plain shank is just visible.
Might be worth checking that the ball is still there, and the bolt hasn't been replaced with something else.

DownUnderXM wrote: ↑

Sat Jun 13, 2020 10:55 pm

Thanks - I knew about the ball bearing and was careful not to undo the bolt too far. Would the system ever get pressure up if the ball bearing was missing? Is there an O-ring, or some other form of seal on that bolt? When I tighten it, should it reach a point where it is obviously tight? This just seemed to get tighter, without coming to a definite stop. Perhaps that diagram might be helpful

Cheers

Alec

The bolt should become rock solid as it tightens onto the ball bearing in its seat.
If it isn't fully tight it will leak.
If the seat has been damaged it is possible to recover it by removing the bolt, then use a punch as a drift, to tap the ball into the seat with a sharp hammer tap.

Try tightening the bolt again, if unsuccessful, remove and inspect the ball and seat, then rebuild.

If the regulator isn't leaking from either the plastic spring cup, or bottom plate, it would s unlikely to need a rebuild.

Must say I've never had to completely remove that bolt, but it does look (from the drawing) that it has its own O-ring.
Might be worth looking at that.

They do have an o ring on the shoulder..

Thanks - now if only access to Service Box was still free, I could find out whether Eathan's 2.5TD has the same regulator, and get a part number for that O-ring!

2.5td regulators are uniqe to 2.5tds as they were initially the only xm to have anti sink. Which uses a different regulator..

The ball and O-ring still showing available for the 2.5... and for V6, the parts are the same...

Thank you so much Chris!!!

So it's confirmed that even though our V6s are anti-sink (like the 2.5TD), the regulator is indeed different. The good news is that the 'drain screw' (as well as the ball bearing and O-ring) is the same.

Might see if Eathan is prepared to send me those bits as insurance, although my money is currently on a stuffed O-ring a) not sealing and b) causing the 'stripped thread' feel of the bolt. On my first Xantia I had a pump O-ring extruded past the threads and out from under it's cap, so I've had some experience with what high pressure oil can achieve!