Case Studies

Mercedes CLK and SLK – Power Top Problem and Repair Service

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Mercedes with the Vario Top

The classic Mercedes SL chassis (aside from being Bruce’s favorite car ever) also know as the SL300, SL500, SLK, and CLK has to be one of the most amazing cars from a electromechanical technology standpoint. First released in 1989 (129 chassis) and are still in current production. The R129 replaced the R107 SL-Class in 1989 and was in its turn replaced by the R230 in 2003 (US). The R129 was produced as a two-door roadster with an automated (electro-hydraulic) textile tonneau cover. All R129s came standard with an detachable hardtop that could fitted by folding the canvas roof down and manually attaching it. 

Vario 2 Mercedes Cylinder
Vario 2 Mercedes Cylinder

The Problem
The technology which makes these cars cool, is unfortunately the technology which can be their undoing. With some of the earlier cars nearly a quarter century of use, the top hydraulics have become one of the weak points in an otherwise rock solid auto. Still, I can’t imagine that Mercedes ever anticipated that these hydraulic systems would still be functioning some 10-20 years later, and it’s only a testimony to their superb German engineering that most still are.

How Not To Fix
You’ll see a number of “snake oil” repairs out there for this problem, additives to “swell” the seals, “new” seals to try to install in your old cylinders (problem is the rams are also often worn, which new seals do not correct), techniques to try and “tighten down” the cylinder caps, you name it. None are a lasting fix, few even begin to provide any even short term correction, and ALL ultimately cost you much more in the end, when the very expensive pump motor fails, or the hydralic fluid leaks and ruins your car’s interior.

Service Kit – Vario 2 Hydraulic Cylinders

The Fix
This is the main cause of failure of the soft top of these cars. The hydraulic seals inside the cylinders are made of material that is not very durable and degrade over the years in the mineral fluid independently whether you use the soft top a lot or do not use it at all. The hydraulic seals usually simply disintegrate. No stop leak is able to fix the problem as sometimes sections of the seal crack away creating a very large, and expensive damage to the interior of the car. The only correct and lasting repair is to replace the cylinders, which usually entails all of them so the problem does not repeat.

Atlantic Motorcar has deverloped some very specific procedures and tooling, combined with our expect technicians, to make this very challenging service last another quarter century!

How We Can Help
At Atlantic Motorcar we’ve deverloped some very specific procedures and tooling, combined with our expect technicians, to make this otherwise onerous repair a snap. Well, maybe not a “snap”, hard to call a day + of labor a snap, let’s just say that we make it flow very, very smoothly.

All told, the power hydraulic system on the 170 is compromised of number individual cylinders that do everything from unlatching the top, to moving the convertible top out of the way, and folding securely in the boot. If the soft top of your beloved SLK roadster, or for that matter W129 or 124 Cabriolet, is not working any more or is very slow, chances are that the hydraulic cylinders that operate the top are leaking.

Questions, or if we can be of help in any way with service on your Mini Cooper, BMW, or other European (and now Japanese) import, please contact us. Our team of Service Specialists are here to help, for even the newest autos! (207) 882-9969.

Knowing, not just “doing”, that’s the Atlantic Motorcar Center way of life.

The Atlantic Motorcar Center Service Team


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