Trouble with tops - 2007-2011 Bentley Continental GTC convertibles

2007 Bentley Continental GTC at Robison Service

Over the years, Robison Service has acquired a reputation for knowing convertible tops on Rolls Royce and Bentley cars.  As a result, we see cars with all manner of problems.  Intellectually challenging as that may be, it sometimes makes me long for the days when service was simple and the only convertible top problems we saw were from something obvious, like vandalism.

This week we saw out first failure of a new Continental GTC top mechanism.  This car came in with an opening problem, and damage to the outer fabric.  The owner thought he needed a new outer skin and some straps he’d seen broken.  He’d done some research online and found people talking about strap breakage, and the holes in his outer skin made that part of the problem self-evident.

However, as is often the case, we found more to the story.  When we cycled the top we saw the rear edge of the top (which folds up) was scraping the edge of the swing-up boot.  This had been going on long enough to scuff the paint from the boot and cut the fabric bead of the top right through to the metal.  In addition, the top was folding wrong, and there were several patched holes to the left of the rear window. 

“The dealer I bought it from must have done that,” the owner explained.  He told me he’d assumed the car would need a top, and he’d budgeted $3-4,000 to make the change. 

When we looked closer, we saw that one of the inner securing straps was broken, and the cables and headliner were beginning to unravel on the left side.  It was cleat that something had gone wrong on the left side of the top.  It looks like the straps (which keep the top in place as it folds) had ripped away from the top, which left the top bunch up and tangle in the bows.  We’ve seen that happen on Azure cars, and it often leads to big trouble there, as the tangled fabric causes the bows to bend, and the now-misaligned top will never work smoothly no matter how you adjust it.

Indeed, when we made some measurements, we found the two rear bows were slightly out of alignment or bent.  The way Bentley engineers designed this system it does not take much misalignment to cause a collision between top and boot, with the virtual assurance of additional trouble.

Looking at the workshop manual, it appears the only reliable way to fix this problem is to install a new top assembly, at a cost of $14,500 plus installation.  Looking online, I see there are aftermarket suppliers offering the Haartz top skins alone for $2,800.  However, a skin alone won’t fix this situation.  And once you get into replacing the pad, liner, and inner bow pieces the costs quickly approach that of a complete assembly.

The owner of this car looked at three other similar Bentleys in Florida, and saw the same damage on each.   That makes me wonder if this is a designed-in problem that will plague every Bentley convertible, or if these are just four unlucky people.

So here’s my question:  How many Bentley GTC owners have experienced convertible top trouble?  What was done to fix it, and how long has the repair lasted?  

John Elder Robison

About John:

John Robison is the founder of J E Robison Service Co of Springfield, MA. His company specializes in the repair and restoration of Rolls Royce and Bentley motorcars.  John is also known as an author and advocate for people with autism and neurological differences.  His books include Look Me in the Eye, Be Different, and Raising Cubby. John has also written numerous articles on Rolls Royce service and repair, and he’s a frequent contributor to the RROC technical forums. He’s always available to advise owners about the care and feeding of their fine motorcars.  www.robisonservice.com  413-785-1665

Jaguar XK8 and XKR convertible top hydraulic problems

I’ve written a few articles about the issues with Jaguar XK8 Convertible top hydraulics over the years.  I’d like to begin by referencing Jaguar’s own technical service bulletin on this topic -

TSB 501-33 -  1997-1999 Convertible Top Operating Slowly - Amended April 2003

Issue: early XK8 Convertibles may experience slow operation of the convertible top, or slow or erratic operation of the latch. These conditions are caused by a tendency of the Univis hydraulic fluid in the system to slowly evaporate, and in certain conditions to gel within the hydraulic system pipes and hoses. From VIN 037189, vehicles in production have been filled with an improved fluid, Pentosin CHF 11S.

The service bulletin informs us that the fluid may gel, and the top may stop operating as a result.  On the face of it, the story sounds pretty benign.  Lately we have seen things take a turn for the worse.

During the past six months three early XK8 Jaguar convertibles came into Robison Service with slow convertible top complaints.  Two cars were leak free; the third was showing the familiar hydraulic oil drip from the header bar.  On each car we found original fluid in the top hydraulics.  Two of the cars were still in the hands of original owners, and the third had been owned by its current owner since three years of age. All were certain – there had never been an issue with the top before.

After changing to CHF11S fluid (and in one case, changing leaking lines) all three cars developed additional leaks from the ram seals and lines.  Why did that happen, we wondered? 

A close examination of the failed parts offers some answers.  The first clue can be seen in one of the pump reservoirs, shown after thorough flushing and change to CHF11S fluid.  You can see the fresh CHF fluid as green liquid in the bottom of the reservoir.  Above that, lining the bottom of the reservoir, you see a slimy mix of the two fluids.  At the front of the reservoir is a hard lump of what started out as Jaguar hydraulic oil, circa 1998.

We already know the old hydraulic fluid was prone to thicken and solidify in chunks.  What we now know is that those chunks get into the seals of the rams and latch, and chew them up.  But they do not always leak, because the chunks of congealed oil act as leak-plugs, which means the problem worsens with age, while remaining invisible.

All that changes when the fluid is flushed.  All of a sudden you have thin, fast moving oil flowing through the system.  As the chunky old fluid is washed away, leaks appear.  The solution:  Replace the lines, rebuild the rams, and rebuild the latch and pump.  All the chunky old oil has to go, as do all the seals, and total rebuild is the only way to accomplish that.

My takeaway from this:  Change your hydraulic oil, just like any other fluid.  It was the chunky deteriorated fluid that caused the seal damage.  If these cars had gotten top fluid services every five years, there is a good chance this total failure would not have happened.  Having said that, I must also point out that many carmakers (Jag included) use plastic hoses now, and those get brittle and fragile no matter what’s in them.

The lesson for owners of pre-2000 XK8 convertibles:  If you have trouble with the top, be prepared for the possibility of leaks after flush, and if that happens, rebuild the whole thing and have done with it because the alternative will be replacing everything one part at a time, which will cost you a lot more in the end.

John Elder Robison is a NY Times bestselling author and the founder of J E Robsion Service of Springfield, MA.  Robison Service is a long established Jaguar service specialist, with expertise in postwar Jaguar motorcars from 1950 to the present day. Find them online at www.robisonservice.comor in the real world at 413-785-1665