Hydraulics

Twelve rams, one noisy pump, green blood.

Pentosin CHF 11S (green). Never ATF, never engine oil. The reservoir sits on the pump in the trunk, under the spare-wheel foam. Fill to the mark — typically about half. Overfilling aerates the system and the top will shudder and stall.

Pinch to zoom · drag to pan

Roof / roll-bar hydraulic pump

Trunk, under the spare wheel and the shaped foam. A second, smaller unit in the same well is the PSE pneumatic pump for the locks — do not confuse them.

The roof switch (centre console) talks to the roof control module. The module runs the pump and the solenoid valves in a strict sequence, watching limit switches and window Hall sensors. Skip a switch and the sequence aborts.

A healthy pump is loud and brief. Silent: fuse 7 (30 A) in the trunk, then power/ground at the pump, then the module. Always-on: a stuck relay or a module that never sees ‘sequence complete’. Whirring forever: internal cylinder bypass or empty reservoir.

Open / close sequence

Windows drop a few centimetres (Hall sensors must be in sync).
Front header locks release.
Tonneau unlocks and opens.
Main lift raises the top off the header.
Bows extend / fold in order.
Top settles into the well (open) or onto the header (close).
Tonneau closes (open) or front locks clamp (close).
Windows rise.

Main lift cylinders

qty 2

Left and right, in the well behind the seats / along the C-pillar path. These are the big ones that raise the whole top off the header and out of the well.

Primary raise and lower of the convertible top.

The classic leak. Red-green slime on the carpet behind the seats. Top creeps down overnight or stalls halfway. Rebuild or replace in pairs.

Bow-extension cylinders

qty 2

Along the side rails, driving the tensioning / rear bow geometry as the top unfolds.

Stretch the fabric into shape and fold the bows in the correct order.

Top goes up but looks like a badly pitched tent; fabric hangs. Do not drive it — you will crease the cloth. The microswitch on some of these cylinders will permanently halt the sequence if broken.

Tensioning-bow cylinders

qty 2

Rear bow, above the tonneau when the top is up.

Pull the last bow into the locked, taut position.

Top is ‘up’ but the rear edge will not seal. Wind roar and wet seats. Often blamed on the fabric when it is these two cylinders.

Front header lock cylinders

qty 2

Windscreen header, left and right. Small, vicious, and the first to drip onto the dashboard pads.

Drive the latches that clamp the top to the windscreen.

Top will not unlock from the header, or will not clamp down. Fluid on the A-pillar trim is the giveaway. There is a front hydraulic distributor nearby — it weeps too.

Tonneau-cover cylinders

qty 2

Under the rigid tonneau that hides the folded top.

Open and close the tonneau in sequence so the top can enter or leave the well.

Tonneau stays shut (top trapped) or stays open (looks unfinished). Check the tonneau limit switches before replacing cylinders — a $20 switch aborts the same way.

Rear lock / latch cylinder

qty 1

Centre rear of the top, where it latches into the body / tonneau.

Lock the folded or raised top at the back.

Sequence reaches the end and then undoes itself. Scan the roof module for ‘rear lock not confirmed’.

Roll-bar cylinders

qty 2

Behind the seats, the hoop itself. Share hydraulic pressure with the roof pump on most cars.

Raise the bar on command or in a crash. Must still work even if you never put the top down.

Bar leans, creeps, or refuses. This is a safety item — do not ignore a lean. Separate trunk fuse (position 4) plus the shared pump.

Lines

Pump pressure and return

Short hoses from the trunk pump to the first bulkhead unions, then rigid / flex lines along both sides of the well.

Foam in the spare well soaked green. Replace O-rings at the pump banjo before you rebuild every cylinder.

Side-rail lines

Run with the wiring inside the convertible-top frame. Flex and age together.

Cracks at the bends near the main-lift cylinders. A line leak here looks like a cylinder leak — wipe, cycle once, and watch.

Header / front-lock lines

Up the A-pillars into the windscreen header. The hardest to see and the messiest when they let go.

Sticky headliner at the front, fluid on the sunvisors. Drop the header trim; do not keep cycling.

A roof that does nothing at all is electrical (fuse, module, switch, battery voltage). A roof that starts and then stops is hydraulic or a limit switch.
Never operate the top with the hardtop fitted.
Never sit on the tonneau. Never force a stalled sequence — reverse it once, then diagnose.
After any battery disconnect, resynchronise both windows (hold the switch down, then up, a few seconds past the stop).
The emergency manual procedure uses the vehicle tool kit. It is for getting home, not for daily use. If you break a microswitch on a bow cylinder, the top will not run until that switch is replaced.
Rebuild kits exist for every cylinder. Rebuilding all of them at once is cheaper than doing them one panic at a time.

Stuck? Walk the roof tree