“My Bentley overheated, and now the engine is smoking.” As
the cars age, I hear that more and more from Turbo R and Azure owners. As the story unfolds, the narrative often
runs something like this:
“I pulled out of my driveway and went down to the ramp for
I-95. I gunned it to move up the ramp,
and accelerated to 80 in the left lane.
I looked down a moment later and the temperature gauge was all the way
to the right. I started to pull over,
and the engine stalled. When I started
it back up, smoke came pouring out from under the hood. You’ll have to send a wrecker for it.”
Steam comes out of the head bolt holes on a Turbo R with blown gaskets |
Coolant leaking from head bolts is a sure sign of head gasket failure, and maybe more damage |
People describe the problem as head gasket failure, but it’s
often quite a bit more involved. And
it’s happening more and more as these fine cars age.
When you look at the motor on one of
these cars you may actually see
coolant coming out around the head studs as shown in the photos above. Most times, though, you don't see anything but steam from the radiator and bubbles in the expansion tank. What’s that tell us? It means the head gasket has blown out, and the
motor has to come apart.
A Bentley engine with heads removed (c) J E Robison Service |
An assembled Bentley Turbo motor, vintage 1996 (c) J E Robison Service |
How far apart, you ask?
It depends on how much damage the engine has sustained. It's hard to know that until it's taken apart, and even then you may not be able to tell. The only sure cure for overheating damage if a full rebuild, which few people want to do. So we take apart the top and see what we can see . . .
Rolls-Royce Bentley V8 with 20 head studs on each side (c) J E Robison Service |
To begin, all the turbo and intake piping comes off,
and the valve covers are exposed. The
covers come off, as do the rocker shafts and exhaust manifolds. The head bolts are now exposed, 20 of them on
each side. The first clue to the extent
of damage is how tight those bolts are.
If they are still torqued that’s a good sign. If they are loose you should expect some
trouble and possibly a number of pulled studs.
Once the head is off you can often see the blowout. In my experience the cylinders that are
physically closest to the turbocharger are the most likely to fail. The next photo shows a blown head gasket.
When the fire ring fails (that’s the part of the head gasket
that seals the combustion chamber) the combustion gases burn through the inner
gasket material and pour into the cooling passages. Check out the closeups in the photos below. The hot combustion gas fills the cooling
system with bubbles, which reduces the efficiency of the coolant. It also pushes coolant out the radiator
overflow as the system is over pressurized.
Bentley Turbo - head gasket blown at the bottom on both cylinders (c) J E Robison Service |
That is the means by which head gasket blowout translates
into an overheating failure. But that’s
just the first step . . .
When the engine overheats the metals expand. The aluminum block expands more than the
steel studs, so the tension on the studs rises as the motor heats up. That’s good to a point, because it makes the
head gasket clamp tighter at normal temperatures. But when the motor overheats – particularly
when an area near a stud gets really hot – problems develop.
When the aluminum expands the stud stretches, and the gasket
compresses . . . to a point. Beyond that
point, the studs pull out of the block, taking the threads with them.
Here’s a pulled stud, with strands of aluminum block
clinging to it.
Bentley head stud with threads pulled (c) 2014 J E Robison Service |
Head stud and insert (c) J E Robison Service |
A repaired head stud (c) 2014 J E Robison Service |
The most common stud failures are on the top and bottom rows. That's lucky, because the center rows studs can't be fixed without stripping the block. If you fix studs, it's absolutely critical that you drill the repair holes straight. If the studs are even a little bit crooked the head won't go on! The photo below shows the alignment fixture we use to drill straight holes.
- Rebuild long block engine after major failure - $35,000
- Replace melted injectors and rail parts - $3,000
- Replace water pump, radiator, coolant hoses and thermostat - $3,000
- Replace other heat-damaged parts - turbo, pipes, possibly catalyst - $3-6,000
- Labor for all this work - $10,000+
All you can do is shut the motor off the moment you see it's overheated, and hope your case is not the worst case.
When an engine has gotten hot enough to pull studs you have
to look for other issues. The first is
warpage. The heads are almost certainly
going to be warped, and we would surface them as a matter of course. The mating surface on the block – called the
deck – may also be warped, but it’s not so easy to fix that. The only way to true a warped deck is to
remove the motor, strip it completely – including stud removal - and then
machine it flat. It's very common for people to skip this step - "just throw some new gaskets in and per er together" - but that really just sets you up for later failures, often worse than the first one.
Here’s a cylinder head after it’s been surfaced. The surface is uniform and smooth but we had to shave off .008 to achieve that. If we had skipped that step the head gasket would have been overstressed in the high spots and under stressed in the low ones. That's why surfacing is important.
We also do a full valve job, to ensure the car runs as smooth as possible. I often see shops skip this step too, but why? If you can spend a few more hours here and get a smoother car, why would you not do that?
We also do a full valve job, to ensure the car runs as smooth as possible. I often see shops skip this step too, but why? If you can spend a few more hours here and get a smoother car, why would you not do that?
Bentley cylinder head ready to install (c) J E Robison Service |
When studs pull out of the block you have two choices. Mild damage can be fixed with a Heli-coil
insert. More major damage calls for a
solid insert. In both cases the fitment
of larger inserts between the stud and the block makes for a stronger joint
than original. That means we can assemble with 110% of the original torque, which reduces odds of failure even more. Strong studs - strong engines.
What's the typical repair consist of now?
- Remove heads, clean all parts, and check for damage. Always pull both heads, even if only one is blown. If you don't, the other side will fail soon after. We have learned that the hard way.
- Check the heads for cracks and warping, and do a full valve job with guides and seals.
- Check all the injectors and replace all fuel injection o rings.
- Replace the thermostat, belts, and other consumable parts.
- Use a fixture to test torque the head studs 20% tighter than stock and ensure they do not begin to give way when left overnight. Repair any that are marginal.
- Use a gauge to check block flatness and consider full overhaul if the warpage is more than .004
- Replace all the hard rubber hoses in the center engine area - this is your time to get at them easily.
When you do all this work, you always wonder . . . is this
as deep as the damage goes?
Unfortunately, there is no way to know, short of total engine
disassembly. It’s possible the pistons
have seize damage, and it’s possible the liner seals are damaged. There are other possibilities too, but they
are less likely. You can look for evidence, but if there's nothing to see you have to put it together and hope for the best.
What can you do to check for other damage?
- Look at the cylinder walls for signs of scraping. That could be evidence of piston damage. If you see this, the engine should be removed and the pistons pulled.
- Look at the oil, and sniff it. Is it burnt? Burnt oil is a very bad sign because it means the core of the motor got very hot.
- Look at the amount of warpage in the deck. If you have .003-.005 of warping (measured with a good straight edge) that’s probably ok. .010 of warping and you may have bigger problems that will necessitate engine removal. When the metal is warped at the top it may be warped at the bottom, and if the crank journals are out of true the engine will eventually fail.
Bentley engine - always check the desk surface for warpage (c) J E Robison Service |
We use Copper-Cote to help seal the head gasket after a blowout. Reassembly of a Turbo R (c) Robison Service |
Bentley Continental T (c) J E Robison Service |
Bentley Azure (c) J E Robison Service |
Bentley Turbo R (c) J E Robison Service, Springfield, MA, USA |
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
8 comments:
hi , i am looking at 2002 Arnage and would like to know if they still have issues with head gaskets, i have also heard about camshaft failures, are there any signs that would point to such problems when inspecting the car? how much does a change of camshafts cost? . thanks . stefano
A 2002 Arnage with the 6.75 liter engine is at risk for head gaskets but I think it will be too early for the cam problems. Head gasket repair could run $10k and up, depending on whether the engine sustained damage when the gasket failed
Bought a 2000 Arnage Red Label several years ago and went through the torture of head gasket failure as so expertly desrcibed above. I did not pay much for the car, thankfully, and I would do it all over again. Total cost for the repairs was around 17K. All of the gaskets and o-rings were replaced. Today "Burtha" has 110K miles and runs like the champ she was designed to be. It's was a good experience because I can now bargain even better when I pursue an Azure of the same error. By far the best car I ever owned.
I was thinking of purchasing a 2003 Arnage T with 50,000 miles but then I read of the potential head gasket, camshaft, rear suspension, front suspension, wheel bearing, power steering hose, navigation failure, etc. While I love these cars, I think it might be a better idea to wait until I can afford a 2007 or newer that made some changes.
what did VW do to the 2007 and newer Bentley Arnage T to increase the reliability and prevent the head gasket & cam problems? Have you had any of these fail yet? Would it still be safe to buy an earlier car if it had low miles or are they all prone to fail due to age, etc.
I recently bought a 1969 Rolls Royce Shadow California but unfortunately blow air in water circuit, possibly because the cylinder head gasket. I removed all the components of the cylinder head and the 20 screws, but can not remove the cylinder head, not even moving, as if it is welded. I tried to push with plastic wedges with lever and turn on the electric motor to make pressure cylinders, but still nothing. Please help me with an idea what to try so as to not destroy the cylinder head.
Thank you in advance
Hey John, I work at an import garage in south Georgia. We have a 1997 Bentley azure that was towed in with several fuel leaks. I managed to tear it Down to the injectors but has taken longer to receive parts than we realized. Is there a way you guys could send me a diagram of the ram pipes and hoses? There is no information to be found in our repair program nor on google. And if google does have anything, it would take entirely too long to find. I have it most of the way back together but I want to make darn sure it is right before I try to crank it. I came across this website before we left work today and the boss wrote your number and email address down in case you are able to help. This is the first one we have ever touched and I want to fix it right.
I have a Bentley Turbo R, 1997.
At about 62k miles the head gasket went. Costly repair and speaking to garages and other owners it seems that around the 60k mileage mark this is not unusual on Turbo Rs (or others possibly?)
Probably depends on how car driven in its life maybe, but if considering as a future buy, do check service history for gasket probs, especially if the 60k is there or near.
Strangely, two used car dealers in the UK that friends contacted with a view to buy, did not reply to emails asking about head gasket replacement on cars they advertised so the prospective buyers went elsewhere, possibly very wisely.
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