Lhm pump leaking...

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Kris1998Xm
XM newbie
Posts: 2
Joined: Sun Aug 31, 2025 1:24 am
Orga / RP numbers: 7737

Lhm pump leaking...

Post by Kris1998Xm » Sun Aug 31, 2025 1:54 am

Hi there,
I m new to the forum, and newer before own any Citroen...
I found very clean unmolested example of 98` XM V6 3.0 originated from Switzerland and decided to ship it home.
When arrived after more one month here I discovered leak came from Lhm pump plug look like 18mm in size just above alternator.
Have questions regarding how ( assuming there is high pressure in system ) to set up the car and de pressurize it to be able to get to the problem.
Can anybody help ? Thx.

Dieselman
Global Moderator
Posts: 14643
Joined: Thu Jun 18, 2009 6:44 pm

Re: Lhm pump leaking...

Post by Dieselman » Sun Aug 31, 2025 5:50 am

With the engine running set the car to low then undo the 12mm bleed bolt on the regulator until pressure is released (about 1/2-1 turn). Do not unscrew fully as the internal ball can be lost.
Switch off the engine.
The system is now depressurised and safe to work on.

Union O rings are
4026 87 DIAM 16-TO 1,9 (2 off)
4026 88 DIAM 19-TO 2,4

If not using Citroen parts use 90 shore O rings for longevity.
91 3.0 sei M. 4852 EXY Black
92 2.1 sed M. 5740 ECZ Sable Phenicien
92 3.0 V6-24. 5713 EXY Black
92 2.1 sd M. 5685 ENT Blue Sideral
Prev
90 2.1sd M. 5049 EJV Mandarin
92 2.1sd A. 5698 EJV Mandarin
94 2.1sd A. 6218 ERT Triton
91 2.0si M. 5187 EWT White

xantia_v6
XM Guru
Posts: 1793
Joined: Sun Mar 31, 2013 5:09 pm
Location: Christchurch, New Zealand or Beaune, France

Re: Lhm pump leaking...

Post by xantia_v6 » Sun Aug 31, 2025 6:07 pm

My advice is to buy Viton o-rings with a cross section 0.1mm larger than the original.so that becomes 16x2 and 19x2.5.

I think that it is the larger seal that is 2 off and the smaller 6 off.
I usually buy them on eBay.
1999 XM Exclusive V6 24V ES9 Manual (LHD) 115,000 km
1997 Xantia Exclusive V6 (RHD) 51,000 miles

Kris1998Xm
XM newbie
Posts: 2
Joined: Sun Aug 31, 2025 1:24 am
Orga / RP numbers: 7737

Re: Lhm pump leaking...

Post by Kris1998Xm » Sun Aug 31, 2025 8:34 pm

Thanks guys, one more think is the car need to be leveled when is depressurised or can I lift up front using floor jack?
Need to take A/C ( do not have gas) and Alternator off the car. Alternator got some LHM so need to be clean up.
Second problem is A/C where is the high side inlet? Found lower side, but can`t spot the other.
Thanks!

Dieselman
Global Moderator
Posts: 14643
Joined: Thu Jun 18, 2009 6:44 pm

Re: Lhm pump leaking...

Post by Dieselman » Mon Sep 01, 2025 6:42 am

Due to the anti-sink valve closing, You won't be able to fully depressurise the relevant suspension circuit with the wheels hanging, but you're not working on that circuit, you are working on the primary circuit which will depressurise by loosening the 12mm bleed bolt.
91 3.0 sei M. 4852 EXY Black
92 2.1 sed M. 5740 ECZ Sable Phenicien
92 3.0 V6-24. 5713 EXY Black
92 2.1 sd M. 5685 ENT Blue Sideral
Prev
90 2.1sd M. 5049 EJV Mandarin
92 2.1sd A. 5698 EJV Mandarin
94 2.1sd A. 6218 ERT Triton
91 2.0si M. 5187 EWT White

xantia_v6
XM Guru
Posts: 1793
Joined: Sun Mar 31, 2013 5:09 pm
Location: Christchurch, New Zealand or Beaune, France

Re: Lhm pump leaking...

Post by xantia_v6 » Mon Sep 01, 2025 6:56 am

Kris1998Xm wrote:
Sun Aug 31, 2025 8:34 pm

Second problem is A/C where is the high side inlet? Found lower side, but can`t spot the other.
Thanks!
On the drier next to the battery?
1999 XM Exclusive V6 24V ES9 Manual (LHD) 115,000 km
1997 Xantia Exclusive V6 (RHD) 51,000 miles

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