Citroën BX – Suspension Fluid Leak

3 min read

Last month I changed the LHM suspension fluid on the Citroën BX to Total Hyrdaflush [READ MORE], and finally had the car re-piped. I’ve been running the car and performing “cit-aerobics” periodically and today I noticed, the horror of horrors. A hydraulic leak on the Citroën BX, next to the suspension!

Finding the source of the leak

Hydraulic suspension fluid leak on drive
Hydraulic suspension fluid leak on drive

This is actually three separate puddles, I suspect as a result of parking in slightly different places following essential journeys. Ironically the last one was an emergency trip to Toolstation after a leak sprung in the bathroom plumbing!

One of the best and worst aspects of the Citroën BX is the hydraulic system which powers the suspension, steering and brakes. The puddles are obviously under the LHM reservoir and a quick look under the made it clear the fluid was coming straight down from the tank area. Bonnet open and the location of the leak was confirmed.

Overflowing Reservoir

A lake of shiny, leaked, suspension fluid
A lake of shiny, leaked, suspension fluid

The picture isn’t the best for showing the puddle of fluid. The area under the tank is sopping wet with LHM. The trail runs over the chassis leg (towards the alternator) and flows down. The fluid then tracks back across the underside of the chassis box section and down the side of the tie-down point.

The fluid level was high, not so high that it was overflowing, and about where I had filled it to when putting in the Hydraflush. Surely it should be lower if it’s leaking so much? I brought the suspension up and down a few times, then took the cap off.

Bubbles in the Fluid

Suspension fluid bubbles and plenty of them
Suspension fluid bubbles and plenty of them

What I saw was rather yellow looking LHM, which seemed odd the fluid was less than 100 miles old. With some better light, I could see that the fluid wasn’t yellow but heavily aerated. The picture above doesn’t do justice so just how much air was initially mixed into the fluid in the tank.

I drew the conclusion that the tank was overflowing when the hydraulic fluid foamed up. After a little thought, I reasoned that the most likely place for air to be getting into the fluid was the feed pipe to the pump.

Finding the source of the bubbles

Wet suspension fluid pump is a giveaway to the cause of the leak
Wet suspension fluid pump is a giveaway to the cause of the leak

The reservoir end of the pipe looked okay. Looking closer the pump was damp. A clear give away as to the route cause of the air getting into the system. The hose clamp was slackened off, turned a little to re-seat, and tightened back up.

Hopefully, this will be enough to sure the Citroën BX suspension leak. Restarting the engine didn’t immediately show foaming in the tank. I suspect air has been creeping in when the car is idle. I’ll give it a day or two before starting her up again, and see what happens.


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