Inspecting Rolls-Royce and Bentley hydraulic systems

How to test and inspect the brake and hydraulic systems in Shadow and Spirit/Spur era Rolls-Royce and Bentley motorcars.

Disclaimer: This article describes a process whereby a knowledgeable owner can get a good approximation of a car's hydraulic system condition in the field without specialized test tools.  It is not meant to replace the procedures described in the factory workshop manuals. Rather, it recognizes that the workshop manual procedure relies on specialized hydraulic gauges which are unavailable to most owners around the world, and the need to test brakes is more widespread than the proper tools to do it.

1983 Corniche drophead (C) JE Robison

The advice in this article is provided as-is, with no warranty as to completeness.  I've done my best to illustrate a complete procedure but there are inevitably circumstances where a car might experience a hydraulic problem that would be missed by this simplified test, yet found by the factory procedures.  Always use the gauge tests if you can  

One of the more unique features of 1965-1998 Rolls-Royce motorcars is the hydraulic system.  The hydraulic system powers the brakes and the rear suspension’s height control.  These systems are legendary for their complexity and potential for bank-breaking repair costs.  In this essay I'll show you how to check yours out so you can get a sense of what's happening before disaster strikes, and hopefully avoid disaster altogether.

The early version of this system (1965-80) is filled with a derivative of conventional brake fluid (RR363).  RR363 is essentially brake fluid with an added lubricant.  The lubricant is needed for the engine driven pumps. Newer cars (until the advent of the Silver Seraph series) used Castrol hydraulic system mineral oil, or HSMO, which by its nature lubricates the pumps and powers the brakes.  The two fluids are not compatible.  Use of the wrong fluid in a car will cause severe system damage.  All reservoirs are clearly labeled RR363 or HSMO.

RR363 fluid reservoir as used from 1966-1980.  Note warning label and style - a simple steel container, normally painted silver as shown.  Windows to check fluid level are visible on the side.

Mineral oil reservoir (and fill bottle) from a post 1980-Rolls (1995 shown) Style varies by model year but colored warning and symbols are the same. Floats to indicate fluid level via a green dot are visible atop the reservoirs.

The fluid in these systems should be changed annually.  Some owners question the need for this, when their cars are rarely driven.  Here's why it needs to be done:  The hydraulic pumps deliver fluid to accumulators where they compress nitrogen gas under very high pressure.  The fluid is separated from the nitrogen by a rubber barrier, but it is inevitable that some nitrogen will make its way into the fluid.  This forms bubbles, and bubbles in the fluid cause the brakes to pull and act erratically.

Any car that has been sitting a long time is sure to have "funny feeling" brakes for this reason  The cure:  Change the fluid annually.

The system contains two hydraulic circuits that operate in parallel for the brakes.  One of the systems also powers the rear height control.   Hydraulic fluid is stored in reservoirs on the left fender well.  Lines carry the fluid to the hydraulic pumps, which are located in the center top of the engine; under the carburetors or the fuel injection.  High-pressure pipes carry the hydraulic fluid to the accumulators under the motor.  From there excess fluid is returned to the reservoirs.  Braided lines carry the high-pressure fluid to the distribution valve assembly located under the driver seat. 

Rolls-Royce brake distribution valves (all Shadow and Spur era cars similar) under driver seat

A network of steel pipes carries hydraulic fluid to the calipers at each wheel and to the rear suspension and height control.   The rear suspension contains height control valves, shocks, and gas springs that sit above the shocks in the trunk area.

All the pumps, valves, and moving parts are subject to failure.  Calipers rust or leak.  Gas springs and accumulators lose their gas charge.  Metal lines rust and rubber hoses deteriorate invisibly.   A system this complex can only be fully tested by trained people using special tools in a workshop.  However, it’s possible to do a pretty good “quick check” without tools, using the following procedure:

Begin with the vehicle sitting, engine cold.  We start by discharging the hydraulics. Get in the car and slowly but steadily pump the brake pedal 25 times.  Open the hood and check the level in the hydraulic reservoirs. (see illustrations above)  If the level is low, look for leaks (as evidenced by wet spots on the calipers, the hoses, or the engine pumps or accumulators) Turn the key on but do not start the engine yet.  You should see two lights illuminated, identified as Brake 1 and Brake 2.  Depending on the year of the car these may be in an electronic unit between the gauges, in a group of lamps to one side, or by themselves in the middle of the dash.

If you do not see the lamps, or if only one is lit, give the brakes 10-20 more pumps.  If the second light does not come (or if neither come on) on you can assume that warning circuit is broken.  That is a big red flag.  A car whose brake safety lamps are not working is not safe to drive, as it could have total brake failure with no warning. To proceed with testing, start the car.  Watch how long it takes for the lights to go out.  They will typically flicker briefly before extinguishing. If one or both lights do not go out you probably have one or two failed pumps, which is a no-drive fault.  If the lights remain on more than 20 seconds the hydraulic pumps are probably weak.  That's not a no drive fault but it indicates the need for professional inspection and probably service.

Run the car 2 more minutes, shut it off, and turn the key back on.  Begin slowly pumping the brake and note how many pumps before the Brake 1 and 2 lamps illuminate.  If you see the lamps come on (either or both) in 5 pumps of less, the car is not safe to drive.  If the light comes on within 5-10 pumps the car should be driven carefully straight to the workshop. Less than 20 pumps indicates the car has weak accumulators and should be serviced soon.

You want the car to endure 20+ pumps without either light coming on.  That indicates a system with sufficient charge to provide a margin of safety in braking, particularly if the engine stalls at highway speed or on a hill.  If you do not get to 20 pumps before seeing a lamp, in each case, the repair needed would be to replace (Spur) or rebuild (Shadow) the accumulators and overhaul the valve bodies.  After that the system would be bled.

** MAKE SURE THE CAR IS IN A SAFE PLACE FOR THE NEXT TEST.  It may lunge and roll when put into gear.  Be sure nothing is at risk for damage or impact **

Now, while holding the pedal down at the 20th or 21st press, start the engine.  Immediately pop the car into gear - get it in gear within a second or so of starting.  What does the car do?  If it lurches forward and then stops in a few seconds as the brakes grab, there is a problem in the warning circuit.  If the car holds firm and does not move the brakes and the warning lamps are ok, and it's good.

If the car holds 21 pumps the brake accumulators should be good for a few more seasons.  Brand new accumulators may hold 40 or more pumps but any number in that range is safe.  If you want to know the exact count, run the car till the lights go out, give it a few more minutes, and slowly pump till both lights illuminate.  Usually one will come on followed by the other.

Once that is done, let the car run and wait for the brake warning lights lights to go out.  Go to the back of the vehicle and bounce each corner.  If the car is soft and pushes down a few inches with your weight that’s normal.  If it’s rock-hard that is a sign of failed gas springs in the rear suspension.

Sit down on the rear bumper (even better, have two people sit on the bumper) and wait 30 seconds. You should feel the car lift to the original (and visibly correct) ride height.  If it does not lift that’s a sign of problems in the height control.

Take the car onto the road.  Try braking slowly and quickly.  Pay attention to any pulling or diving that may indicate caliper problems or air in the lines.  Look for any pulsation or shudder that may indicate warped or damaged rotors.  Let the car come to a stop on a gentle slope and release the brake.  Make sure the vehicle begins rolling smoothly and the brakes do not drag.

Shut the car off and put it in neutral.  Press and release the brakes a few times.

Finally, put the vehicle on a lift and make sure all four wheels spin freely.  If any wheels drag that may be a sign of caliper trouble.  Next check all the components for leakage.  Look at the reservoirs (top left fender well), the pumps (top of the engine), the main valves and accumulators (under side of the engine), the distribution valves (under driver seat), the brake lines and calipers, and the rear suspension components.

   

Look at the fluid and make sure it looks smooth and uncontaminated.  RR363 (used 1965-1980) should be almost clear; HSMO (used 1980-1998) is dark green.  There should not be any foam, sediment, or sludge visible.  Color should be consistent. 

Look at the rubber hoses to see if they are original.  If your car is more than 10-15 years old I suggest you replace all rubber hoses as they can swell inside, creating invisible failures.  A swollen hose may cause brakes to drag and overheat.  Old hoses are also prone to bursting.

Original Shadow-era brake hoses, overdue for change (C) JE Robison

New style lines and hoses in a restored Shadow (C) JE Robison

If your car passes all these tests you can give yourself and the vehicle a pat on the back.  If you see potential failures, I suggest you find a specialist and get a more thorough evaluation.


If you liked this story, please leave a comment.  And if you want more . . . here are some of my other RR/B essays


Thoughts on buying a used Rolls Royce or Bentley - applies to Silver Cloud and newer series cars

More thoughts on Spur - Spirit - Turbo era car buying

Thoughts on restoration - applies to all cars

Evolution of the RR/B models - Silver Shadow through Arnage/Seraph - original article from the Robison Service website

Inspecting a Rolls Royce or Bentley - Applies to Corniche, Continental, Azure, Turbo R, Mulsanne, Eight, Turbo R, Silver Spur, Silver Dawn, Silver Spirit

More Things to Look For in a 1981-2000 Rolls Royce or Bentley - this is the original article from the Robison Service website

The last Crewe built Rolls Royce convertibles - applies to 2000-2002 final Series Corniche

Repairing convertible top hydraulics - Applies to 1996-2004 Rolls Royce and Bentley Corniche and Azure cars

Head gasket failures in Bentley Turbo cars - applies to Turbo R, Continental R and T, Azure, Arnage

Checking engines after head gasket failure - Applies to all cars

Checking and inspecting Rolls Royce hydraulic systems - all cars after Silver Cloud and print to Silver Seraph. Applies to all Shadow/Spur era vehicles

Case Study - brake failure in a Shadow - Silver Shadow era cars with RR363

Rear suspension gas springs - Applies to all 1981 - 1999 cars prior to Silver Seraph

Changing batteries in seat and ECUs, Applies to 1980s-1990s Silver Spirit / Silver Spur / Mulsanne /Eight / Turbo R

Changing alarm ECU batteries,  Applies to 1980s-1990s Silver Spirit / Silver Spur / Mulsanne /Eight / Turbo R

Servicing Shadow and Spur series brakes - applies to 1966 - 1999 cars after Silver Cloud and prior to Silver Seraph

Alcon racing brakes for Continental and Azure - Applies to all 1990s cars but most particularly to the final series Azure, which had these brakes fitted at the factory - a unique variant

Fixing Power Steering Leaks - applies to 90s cars with the reservoir above the alternator

Questions and answers on collector car storage - Applies to all cars

Evaluating paint - Applies to all cars

John E Robison

JE Robison Service

RROC Tech Consultant

Robison Service has provided independent service, repair, and restoration for Rolls Royce and Bentley owners all over New England for over 25 years. Our company is an authorized Bosch Car Service Center. We also service Mercedes, Jaguar, Land Rover, Porsche, and MINI motorcars. We have flatbed transport throughout the region. We also offer local pickup and delivery for cars in  Springfield, Wilbraham, Longmeadow, Agawam, Westfield, Northampton, and Amherst.

Convertible Top Repair in Bentley Azure / Rolls Royce Corniche

Convertible top hydraulics are shaping up as a major weakness in the Bentley Azure and Final Series Corniche from Rolls Royce.  These cars were built from 1996-2004 (a newer Bentley variant remains in production today) and all are vulnerable to this issue.

The Bentley Azure and RR Cornice are fine cars but the tops are a weakness (c) J E Robison

Here’s the problem, in a nutshell.

The engineers at Crewe wanted to design a fully automatic convertible top for the new Azure series.  But they did not have the resources to do a new design; they had to adapt something else that was already out there.  The Mercedes SL500-type design was well regarded, and they chose to adapt it to the Azure body.

Unfortunately, the design didn’t work as well on the RR/B.  It’s remarkably reliable on the Mercedes, and astonishingly flimsy and incredibly costly to fix on the Azure.  What went wrong?

There are a few essential problems.  First, the systems use very high hydraulic pressures.  Older automatic tops used big cylinders and rams.  With several square inches of ram, you don’t need very high hydraulic pressures to generate the force to move the top.  However, the newer cars use tiny actuators hidden in the top. They are smaller, so the hydraulic pressure needed for a given actuation force rises.  Because the hydraulics are hidden, they are often at a mechanical disadvantage (leverage in reverse) and need to push harder to move the top.

The result:  hydraulic pressures on a 2001 Bentley convertible top can run almost 10 times as high as the pressures on a 1987 Bentley convertible top.  With that factoid in mind, it should not surprise you that the newer tops are not as reliable.

In addition, the newer tops use automatic latches instead of human power to pull it shut and locked.  Those latches are not as rugged as they should be.  Why, you ask?  Look at a Bentley Azure and then look at an SL500.  What do you see?  The Bentley top is significantly larger.  That multiplies the forces on every component and it’s one more reason a reliable Mercedes design didn’t work out the same on the RR/B.

The next problem probably started in Crewe’s engineering department, though I doubt they would admit it.  Mercedes uses plastic lines that are impervious to hydraulic fluid, but that material selection did not translate to RR/B. Someone there chose a hose material that deteriorated with contact with hydraulic fluid.  The result – when they get to be ten years old you see the black rubber casings falling off the hoses, and blowouts inevitably follow. 

How do you check your convertible top hoses?  Look at the hoses in the main hinge area when the top is partly lowered.  Here are examples of hoses that are coming apart.

The upper photo is a closeup of jacketing peeling from a hydraulic hose.  Failure is imminent (c) J E Robison Service

If this problem is ignored you will see leakage, as evidenced by the leaked oil in these photos.

Leaked hydraulic oil in the convertible top well (c) J E Robison Service

Oil seeping from the convertible top hydraulic line bundle 

If you ignore it even longer, you will eventually be showered with oil when a line blows under pressure and the interior of the car is sprayed and damaged.

Header bar line with deterioration.  These are the worst if they blow

"Green showers" most often come from the header bar, when the lines above the rear view mirror blow out.  The reason those lines are the first to blow is that area takes the most beating from the sun. In a hot climate that area can be over 200 degrees all day, and the oil they originally used breaks down into a green jelly that won't pump, and causes pressure surge and blowouts.  Jaguar is known for having this problem too.

The new hydraulic oils are synthetic and they resist this, but the moral there is - change your top hydraulic fluid every few years, or else.

When the top is partly folded there is another thing you want to check – the cables.  These new automatic tops need to fold into a tight space to be hidden under the rear deck.  To do that they rely on cables sewn into the top lining.  Loops of wire around those cables pull the top fabric against the bows and fold everything properly.  If the cables break the top will jam in the bows, and if the bows bend as a result – you have big trouble.

Broken stay cable on Bentley convertible top

In most of these cars you will see leakage from the hydraulic actuators in addition to problems with the lines.  Here is a set of actuators removed for service.  We rebuild these units rather than replace them.

So how do you fix this?  You remove the trunk lining, and the pump and lines.  Open the convertible top boot and remove the top as an assembly. Remove the cover in the convertible top well, and unthread the lines there.  Remove the rear seat, both side panels, the right side floor covering, and the right side dash and windshield pillar trim.  Remove the windshield header bar covers.  Remove the lines and remaining actuators.  Replace and reassemble.

Sounds easy?  Look for a job time of 60-90 hours, more if you are not experienced or run into trouble.

In the next convertible top installment I will begin to cover the actual repair process.


This article is about the automatic convertible top system used in Rolls Royce and Bentley Azure and Corniche from 1996-2005.  Check out this article for thoughts on the newer Bentley GTC convertible top and its problems

And here's an article on 1997-2005 Jaguar XK8 and XKR convertible tops - they have some of the same issues but are simpler to fix

Good luck

John Elder Robison

Robison Service has provided independent service, repair, and restoration for Rolls Royce -Bentley owners all over New England for over 25 years. Founder John Robison is a long time technical consultant for the Rolls Royce and Bentley Owners Club. Our company is an authorized Bosch Car Service Center. We also service Mercedes, Jaguar, Land Rover, Porsche, and MINI motorcars. We have flatbed transport throughout the northeast region, and we work with Intercity and other transporters for greater distances. We also offer pickup and delivery for cars in  Springfield, Wilbraham, Longmeadow, Agawam, Westfield, Northampton, and Amherst.  Our drivers are available to pick up cars in Boston, Hartford, Greenwich/southern CT, New York, Rhode Island, Vermont and New Hampshire.

Restoration and the future for Rolls Royce and Bentley cars - the 2014 RROC Annual Meet at Seven Springs

This past week I attended the annual meet of the Rolls Royce and Bentley Club at Seven Springs resort in southwestern Pennsylvania.  I’d been invited to give a talk on care and feeding of what the club calls Modern Cars (principally the vehicles made from 1965-1999.)   Other technical people did presentations on older cars, and there were additional sessions on Modern Cars too.  Factory personnel were there to show off the current product lines, and vendors were on hand with books, parts, and obscure restoration materials you never knew you needed, and could never find outside an event such as this one.

Silver Clouds parked at Seven Springs Resort for the RROC 2014 Annual Meet

Behind it all was Pennsylvania’s version of a ski mountain, which turned out to be significantly steeper and higher than it looked as soon as I set out to walk to the top.  When I finally attained the summit I was disappointed to discover the event organizers had cancelled the vintage car hill climb I’d come to see. I had been looking forward to the sight of antique Silver Ghosts racing up the ski trails, throwing great gouts of mud and debris in their wake.  Maybe next year’s meet in Orlando can feature a good old southern Swamp Run instead.

A view of the slopes at Seven Springs

With organized mayhem cancelled I found myself wandering the parking lot, admiring the attendee’s vehicles and wondering what might have been.  There were cars of every era on hand, from the earliest Rolls Royce models to the latest Bentley sportsters.  Over one hundred years of automotive history was there on the grounds.

The cars were parked by rough order of age, which made walking across the lot roughly akin to taking a journey back in time, from the present day to the first decade of the 20^th century.  I wondered who had owned the grand tourers of the twenties, and where they had been.  I wondered where I will be, when I am their age.  I’ll be doing very well to be sitting on tarmac like them, and not buried beneath it.

As I wandered, I realized the groups of cars provided an interesting window into how restoration affects a vehicle population, both in terms of condition and value.

Cars built in the last decade were almost all original, and many remained in near-new condition.  These cars were not really “collectibles;” they were simply expensive used vehicles. Unlike their older siblings, no curation or restoration was needed to keep them nice.  A cool shady garage and regular maintenance will do the trick to preserve these specimens for quite a few years.  None of these cars were restored, as far as I could tell, though some had significant refurbishing.

There were some very fine examples on the show field. You could not miss the enormous effort some owners have put into keeping their late model cars in stunning condition.  That surely has costs, both in time and service expenses.  But those costs are far less that one would pay to put, say, a 1920s Ghost into similar shape.

With care, Bentley and Rolls Royce cars can last 20+ years in original condition

Most of the cars from the 90s were showing some wear, and some refinishing, but many were still in nice original shape.  Quite a few of these cars had been painted, and some had new interior trim.  Many of these cars had received significant mechanical service, while others were obviously badly in need of the same.  Once again, I did not see a single restoration though I did see plenty of well cared for cars.  With continued good care some of these cars may remain nice for a good many more years.

With so many good mostly original examples to choose from, few people will choose to restore these cars at this time.  If your goal is to "get a good one" that can be done by careful shopping.  Those who want to restore grandpa's Bentley will not care about finances and are unaffected by this tradeoff.

Cars from the 80s still showed a lot of originality, which meant many examples were looking somewhat long in the tooth.  There were quite a few “fixed up” cars – vehicles with good repaint jobs, redone woodwork, and the like.  These cars were not restored, but they had received significant repairs – mostly to paint and body. If this sample is an indicator, true restoration of 1980s cars has yet to begin on a wide scale. 

70s cars - the transition zone

Silver Shadow cars from the previous decade (the 70s) were the roughest of the bunch.  There were some very nice examples, but even the nicer looking cars showed heavy signs of aging under the hood, and many showed body and interior wear too.  Clearly, these cars are at or close to the Decision Point age.

The Decision Point age is when you realize the “fix it later” issues cannot be put off any longer.  The car has worn down to the point that it's worn out.  Often the point is reached after a major breakdown, perhaps stemming from deferred upkeep or outright neglect.  What then? Do you fix the car up properly, scrap it, sell it, or put it in storage for a decision another day?

At least one of the Shadows at the National Meet was beyond the Decision Point, with a very nice restoration.  We have another such car in our shop now, which we hope to show at an upcoming meet. Shadows in that range remain rare.

Many of the older, rougher cars would be described charitably as “twenty-footers” while more direct critics would call them rats.  In talking to the owners the problem is apparent.  Book values are low.  Restoration costs are high – way above book.  And many owners lack the means (either money or mechanical ability) to really improve their vehicles.  Just staying even on these cars is a challenge as reliability has gotten so poor. 

Then we step back a decade and everything changes.  We move into the Cloud era and cars of the late fifties and early sixties. Many of those cars had been beautifully and lovingly restored, and it showed.  It was also apparent in values.  Edgy 1970s cars are lucky to fetch $10,000 while magnificent Clouds – just a few years older – bring solid six-figure prices at every classic car auction.

Cars like this Cloud III drop head have skyrocketed in value this past decade

What happened?  We found the transition point in vintage Rolls Royces – the 1965-80 range.   Good examples that are newer will be mostly original.  Rarity isn’t a big factor in cars of that age. Consequently, prices will be based on depreciation from new, and the cars are almost 100% depreciated. The situation is totally different for older cars.  Prior scrappage and lower production in earlier years has made these cars a lot rarer.  For the most part, they are too old to be driven in totally original form.  The best cars are show-quality restorations, and it is these vehicles that set the prices for the class.  If it costs six figures to restore the cars that raises the former $20k "good" used car prices through the roof, seemingly overnight. 

Even the “low value” cars in this age range are getting quality restorations, and that is lifting all values significantly. The question now is when that will happen with the Shadow and newer series.  If a restored 1964 convertible is $300,000, an unrestored 1968 convertible starts looking pretty good at 1/10^ththe price.

But unless that happens on a wide scale, cars in the transition zone are at risk.  Most are in need of significant repair as resale values have sunk to a fraction of repair cost.  Any major repair – paint job, engine overhaul, new interior – is likely to exceed book value.  A few owners are making the investment anyway, because they happen to like these cars.  The question now is which way the trend will go.  Will owners (either current owners or new owners) restore these cars, or will they end up recycled?

Owner demographics come into play.  The owner who stretched to realize their dream of buying a $10,000 Shadow is not likely to undertake a $150,000 restoration of the same car.  Yet a project of that scope would be far less costly than restoring a blower Bentley car from the 1920s, and those owners routinely do such jobs.

Silver Ghost chassis in mid-restoration, at RROC Ghost University

A Rolls Royce Silver Ghost engine

What it takes to restore a chassis - Silver Ghost or Silver Shadow, the job is the same

A run-down and mostly original 1960s sedan fetches $10,000 at auction. As noted earlier, a restored Cloud convertible may bring $300,000 or more at the same sale.  Restoration of these older cars is justifiable and increasingly common as values continue to rise.   Cars of the fifties and sixties are today’s target for high end restoration, but the 70s cars will have their turn any day now.

If I were betting on a future collector market for Rolls Royce, I’d put my money in the seventies.  The older cars have already made a dramatic ascent.  Newer cars are still falling in price.  The 1968-1983 range may be just right.  Buy good ones at these prices while you can!


John Elder Robison is the general manager of J E Robison Service Company, independent restoration and repair specialists in Springfield, Massachusetts.  John is a longtime technical consultant to the Rolls Royce Owner's Club and other car clubs, and he’s owned and restored many of these fine vehicles.  Find him online at www.robisonservice.com or in the real world at 413-785-1665