(07) 5571 6155 sales@mhfgc.com.au

As a hydraulics business specialising in the repair and maintenance of small to medium hydraulic equipment,

we get to witness first hand the effects that time, oil and the heat generated from engines and the sun have on the seals of high-pressure cylinders of modern vehicles fitted with a convertible roof or a sunroof.

Unlike the Holden (Vauxhall) Astra convertibles that usually have their High Pressure Hydraulic Hoses fail, Mercedes Benz, Saab, Porsche and Peugeot fitted with a convertible roof or Sunroof have failures of the High Pressure seals inside their linear actuators or more commonly called hydraulic cylinders or rams that lift, move, close or lock the the convertible roof or sun roof.

Modern Vehicles have a come a long way in the past 100 or so years. Pictured here is a 2016 Porsche Cayman GT4 with 385 Horse power. In the background is the vehicle of the past that required 2 to 4 four legged horsepower to get it to move down the road. The GT4 also uses High pressure Hydraulic Cylinders to adjust the suspension characteristics of the vehicle, depending on the settings selected by the driver and also from data collected and sent by sensors located around the vehicle. This vehicle also comes as a convertible called the Porsche Cayman Spyder. Its not really relevant to the topic but it is such a great picture I just had to share it.    

In our experience, as vehicles reach their 12th to 15th birthday, certain materials that make up some of the high-pressure seals that prevent oil from leaking out of these cylinders will start to partially dissolve, soften or harden, crack and or split and eventually deteriorate to such a degree that oil starts to leak out of the cylinders.

Depending on where these cylinders are located in the vehicle, oil drips and sprays can or may soak into the fabric of the roof or onto leather seats, carpets and trim of the vehicle.

As more and more oil leaks out of the roof’s hydraulic system, eventually it will malfunction, fail and generally a series of warning tones or beeps will be heard as well as indicator lights appearing on the dash board.

Not all cylinders can be re manufactured but a vast majority can and are. We have dismantled resealed and or re manufactured a large range of hydraulic cylinders for various models of Mercedes Benz, Saab, Porsche and Peugeot convertibles.

Generally most manufacturers build or design roof cylinders in a way that saves money, by reducing the number of parts required to manufacture the cylinders and also to speed up assembly. Therefore  most roof cylinders are assembled with permanent style techniques that usually entail the deformation of metal by rolling, squeezing and dimpling.    

Above is a convertible Roof cylinder removed from a Mercedes SLK  the high-pressure oil hoses have been permanently attached to the barrel body by squeezing and deforming the top lip of the oil inlet/outlet port tubes.  
Mercedes Benz SLK 
Mercedes SLK convertible roof cylinders undergoing re-manufacture, this involves careful preparation before drilling, preparation of new parts more drilling, tapping of fine threads, removal of old seals, cleaning and installation of new seals and final assembly and high pressure testing.

Mercedes, Saab, Porsche and Peugeot all utilise some form of permanent or semi permanent assembly techniques in the manufacture of their convertible or sun roof cylinders.

The majority of the cylinders we work on will require careful preparation and measurement before drilling. Some cylinders will require machining and the removal of metal in a lathe followed by drilling and tapping of new threads to insert new locating pins or grub screws.

 All re-manufactured cylinders are bench tested to 1500 PSI (100 Bar) before being returned to the customer. 

Some of the more common Cylinders such as those from Mercedes SLK are completed on an exchange basis so we always have stock available immediately for dispatch.        

Typical larger Cylinder for Solid panel convertible roofs 

As mentioned above the high-pressure hoses are not usually a problem with these vehicle models but we have remanufactured new hoses, installed them back into the vehicle, topped up the oil tank and set the hydraulic system. 
 Most manufacturers are happy to sell you a new replacement component (and preferably a set of components) at a generally steep price such as what Porsche and Mercedes will charge. Other manufacturers such as Saab are no longer in business and most other manufacturers for example Peugeot will not and do not have to keep spare parts for vehicles older than 10 years.
Prices (as at Feb 2019) for cylinder repairs vary from $150 for a Peugeot lock cylinder to $450 for a double-acting Porsche Sunroof cylinder.

For more information or to contact us.

2004 Saab 9 3 Convertible 
Typical Soft top Convertible roof move / fold stretch cylinder from a Mercedes or Saab Convertible these cylinders must have metal removed in a lathe before re-manufacture can begin.  

Mercedes Convertible latch or locking pin cylinder