Citroen XM Forum

Total Transmission 8 is not only recommended, and (down here) standard Citroen gear oil across all models, it actually works extremely well, and produces slick and smooth changes. It is the recommended GL4, correct viscosity (75W80).
On our 2.5, it has resulted in the best gearbox action we've ever had.

There was a giveaway in the specs. PSA PEUGEOT CITROEN B71 2330
TOTAL TRANSMISSION GEAR 8 75W-80 is specially recommended for PSA manual gearboxes, with extended drain interval (250,000 km) and friction modifier additive adapted to PSA manual gearboxes.

though to be fair, I used Comma 75W-80 in the Mandarin car and the gear shifts on that were very slick, probably due to that box only having covered 98k miles.

Derwent Diesels current prices for Purflux fuel filter repair kits.
31D138 - Repair kit Purflux - £7.74 - Contains Rubber Diaphragm and two spring loaded filters.
31D138L - Purflux Rep Kit + Button - £8.93 - Contains Rubber Diaphragm, Push Button, Spring with fixed washer, Metal Button Cap with 4 fixing tangs plus 2 small Rubber Mushrooms (usage currently unknown).
Prices are ex vat and postage was £6.95.

John

I've recently thought the Cobalt car was a bit "springy" when driving over dips in the road and full width speed bumps, coupled with it rocking slightly when encountering camber changes, though generally the ride comfort was pretty good, especially when a passenger, so I thought I'd check the sphere pressures. Another owner drove my car recently and thought mine was very comfortable.

I quickly checked one front one and was alarmed by the result so checked them all.

Fronts: 10 Bar instead of 50 Bar.
Front HA: 30 Bar instead of 70 Bar.
Accumulator: 40 Bar instead of 62 Bar.
Rear HA: 30 Bar instead of 50 Bar.
Rears: 28 Bar instead of 30 Bar.

What is clear is that heat plays a significant part in pressure loss.
Even on the rears, which had hardly lost any pressure, the one near the exhaust was slightly lower pressure than the opposite one.
I had some spare Citroen ones for all three fronts, a citroen "multicouche" for the accumulator, my spare rears were slightly down (26 Bar), leading me to wonder if the valprex valves weep a little, so I put the original the rears back on.
I last charged these spheres in 2016.
I intend to build a recharging rig to move away from using Valprex valves.
I was short of a rear HA, so put an accumulator sphere on, which is the same size (400cc) but higher pressure.

The ride is noticeably better now. It just glides over dips in the road.

Hi Will,

Have suspected a bit of weep, too.
Have only had one Valprex valve seriously lose gas (over 11 days), and that was because of a leaking O-ring. Replaced the ring, and OK.
Recently checked (and topped up) pressures on our corner spheres, which were last regassed 10/2016. Pressure loss was only very slight.
Haven't yet checked the HA's (next job), but ride still nice and soft.
Acc sphere was Valprexed and last regassed in 2013 (!), so well due for a check - but pump ticking is as it should be.

What I have found with Valprex is

O-ring size is same as Cit OE, ring thickness of 2mm.
This sits well down and loosely in the groove, and there isn't much squash when tightened down.
Few years ago decided to try a slightly chubbier Viton ring:
https://www.polymax.co.uk/o-rings-9-19m ... ton-75-sha
which compresses and seals a whole lot better.

Important to lubricate the ring (LHM or silicone grease) to deter it from scuffing as it is tightened.

Valprex sealing plug
Originally thought this was just a stopper, to positively prevent dirt getting in.
Seems it might be an integral part of the gas seal (guessing that the main non-return valve is just ball+seat), and so I'm now putting a smear of silicone grease on the rubbery point, and tightening down properly. Seem ok.

That is a thought regarding the O ring and plug. If it's not actually compressed it won't seal well.
With static pressure of 50Bar the dyamic pressure is 100Bar with the car at ride height and possibly 150Bar when the wheel is forced up due to bumps and undulations.

I have some 2.5mm O rings, so will swap them when regassing, unless I have built a rig by then, so will revert back to solid plugs.

I've only just discovered this thread and been binge-reading it over the last week. What a rich source of tech data and how-tos it is! Well done, Will and thanks for documenting all this great work.