Question

I have problem with my Citroen CX 25 turbo 2 rear brakes. Front work perfect, but rear not! I changed 3 brake valves and same result. All spheres have proper pressure, so I have no idea how find solution.

Citroen Tech Tip

One thing that we have noticed lately here at Citroen Tech Tips is that quite a few people having trouble with bleeding down the rear brakes in most any of the Citroëns with Hydraulic suspension.

What has to be realized is that the rear brakes don’t come into use on these cars unless there is a good bit of weight in the rear because of the brake proportioning system.  This system puts most of the braking force to the front wheels because most all of the weight of these cars is biased toward the front of the car. Plus these cars for the most part have their rear brakes fed by the rear suspension.

The typical situation we hear about. is a person has done some brake work on the car and the system was opened up, or they had a brake accumulator that ruptured or leaked nitrogen into the system. They work on the system and then take the Citroën out for a ride and notice that the rear of the car dives down every time they apply the brakes. An attempt is made to bleed the brakes but no fluid comes out of the rear brake bleed screws.

How to properly bleed down the rear brakes on a Citroën with hydraulic suspension.

First safely put the Citroen up onto jack stands, or on a lift. With the engine running put the Citroën in the highest suspension position. With an assistant applying the brakes in the car bleed the front brakes.

Now come to the back of the car and bleed the rear brakes. It is very important to have a Citroën with hydraulic suspension in it’s high position when bleeding the brakes or you will not get the rear ones to bleed down. This  means even when you have it elevated and the wheels are hanging, because when the wheels are hanging the rear brakes are completely shut of hydraulically unless the suspension is in the highest position.

Good luck and be safe when doing this procedure. Hope this Citroen Tech Tip helps.

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Would you like to know how to do that on your Citroën SM ? Tensioning the secondary chains with the valve covers remaining on the cylinder heads isn’t hard if you know the steps.

It is imperative to bear in mind the grave risk of misaligning the camshafts , causing possible damage to the valves or engine.

When the chain tension is slackened, it is possible for the valve springs to overcome the pressure of the cam lobes , forcing the camshafts out of alignment.

To prevent this:

On the right side…

1. Bring the piston No.1 to TDC of the exhaust stroke.
2. Attach a 6 or 8 mm. socket type Allen wrench to a standard torque wrench . Insert it into the head of the tensioner adjustment bolt and retain a torque of 15 ft.lbs.
3. Loosen the two nuts locking the chain tensioner while retaining the torque.
4. After these nuts are loosened, re-adjust the chain tension torque to 15 ft.lbs. Then tighten the nuts to 15 ft.lbs.

On the left side…

1. Bring the piston No.6 to TDC of the exhaust stroke.
2. Follow the same procedure outlined above.

Hope this Citroen Tech Tip helped and please leave a comment to let me know what other Citroen questions you’d like answered.

Later,

Denis

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