Common faults below

Bentley Engine Carbon Cleaning

What we see most on Bentley engines, what causes it, and which clean fixes it. Every job starts with a scan and a quote at our Kings Park workshop.

Free scanbefore any work
Kings ParkSydney workshop
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Which Bentley do you have?

A Bentley is driven gently and rarely, and that is exactly the problem.

The 2012–2018 Continental GT V8 injects petrol straight into the cylinder, so its intake valves never get washed. The W12 sprays fuel onto the valves, so it rarely needs walnut blasting. Either way, a car that does a few thousand kilometres a year, mostly short and slow, builds deposits on an engine that has barely been used. We regularly find more carbon on a low-kilometre Bentley than on a commuter car that has done far more.

If you have a Bentayga Hybrid, the petrol engine runs less again — and rarely gets properly hot.

Every job starts with a scan, and you get the cost before anything begins.

Common Bentley carbon problems

What we see

If you drive a petrol Bentley

Petrol

Intake Valve Carbon on the W12 and V8

The 2012–2018 Continental GT V8 injects petrol directly into the cylinder, so nothing washes across the back of its intake valves. The W12 sprays fuel onto the valves, so it rarely builds this.
Oil vapour drawn through the breather bakes onto the hot valve stems and hardens.
Each port collects deposits at a slightly different rate, so the engine loses its smoothness before it loses obvious power.

A faint unevenness at idle in a car that should be silent.
Throttle response that has softened, particularly from rest.
Misfire codes (P0300–P0312) with no ignition fault found.
Fuel consumption up on a car that is barely driven.

On the 2012–2018 Continental GT V8, walnut blasting is the only reliable fix for hardened deposits. The intake comes off and every port is cleaned mechanically.
On a W12 we scan first and quote after we have seen the engine. Heavy valve carbon is less common there, because fuel washes the valves.
Caught early, a hydrogen carbon clean will hold it off.

Fixed by

Walnut Blasting

Quoted after the free scan

See the service →

Petrol

Low Kilometres, Short Trips, Long Rests

These cars typically cover very little distance a year, most of it slow and local.
At light load the combustion chamber never reaches the temperature that keeps it clean, so soft carbon settles on valves, piston crowns and chamber walls.
Months parked let fuel go stale in the rail and moisture settle in the exhaust.

The car feeling heavy and slightly flat against how you remember it.
Idle quality varying from one start to the next.
Nothing at all on a scan — just a car that is not as sweet as it was.

A hydrogen carbon clean is the right maintenance step here: nothing comes apart, and it works on soft carbon before it hardens.
On a low-kilometre car we would far rather see you once a year for this than once for walnut blasting in five years.

Fixed by

Hydrogen Carbon Clean

$275

See the service →

Petrol

Chasing a Misfire That Is Not the Coils

Ignition parts are usually the first thing replaced when a misfire appears on these engines.
When the fault returns afterwards, carbon on the valves and injectors is the normal reason — it changes how each cylinder fills and burns.
Across eight or twelve cylinders, small differences add up into something you can feel.

Misfire codes returning after ignition parts have been renewed.
A vibration at idle that mounts and balance checks do not account for.
Rough running that is worst cold and eases when hot.

A full engine carbon clean treats both sides chemically in one visit, which is the right scope when the whole engine is tired rather than one component.
We scan first and tell you what we found. If it is genuinely an ignition fault, we will say so rather than sell you a clean.

Fixed by

Full Engine Carbon Clean

From $715

See the service →

If you drive a diesel Bentley

If you drive a hybrid Bentley

Hybrid

The Bentayga Hybrid

In the hybrid Bentayga the petrol engine starts and stops constantly and often runs at light load.
On short journeys it may barely run at all, and rarely reaches full working temperature.
Deposits build at kilometre readings that look far too low to explain them.

Roughness as the engine takes over from the electric side.
The petrol engine sounding busier than the speed suggests.
A car that has lost a little refinement with nothing stored.

A full engine carbon clean treats the intake and exhaust sides in one visit, which suits an engine that has done a lot of light-load running rather than real work.
These are new enough that prevention is still the sensible option.

Fixed by

Full Engine Carbon Clean

From $715

See the service →

Applies to any Bentley

Keeping your Bentley clean

Prevention

To keep a Bentley W12 or V8 clean, clear the soft carbon before it hardens. Oil vapour from the breather bakes onto the intake valves. Light, slow running leaves soft carbon on the piston crowns and chamber walls too. A hydrogen carbon clean is the maintenance step, and nothing comes apart. On a Bentayga Hybrid, the petrol engine runs less again and rarely gets properly hot.

If the idle is no longer silent, or the throttle has gone soft from rest, book a time at our Kings Park workshop. We scan it free first, tell you what it needs, and quote before any work starts. Valve deposits that have hardened may need walnut blasting. If the whole engine is tired, it may need a full engine carbon clean.

I took my 2008 Mini Cooper S (70,000km) for a carbon clean by Nas. Since I got the car, it has always been a little hesitant to accelerate and I felt it was struggling to breathe at high rpm. I took it to Nas to do a full walnut blast and hydrogen clean. WOW – What a difference! The car now revs freely all the way to redline. It will leap off the line and all the low rpm hesitation is gone. The car has been transformed into a little pocket rocket as the factory intended. Nas is a trustworthy and guy and generous with his time. I highly recommend a carbon clean service from him to restore your engine's performance. DO IT!

Schreuder Engineering, 2008 Mini Cooper S · Google review

Before any engine work on your Bentley, search your VIN on the government vehicle recalls site. Recall repairs are free, so check there first.

Don’t stop at new ignition parts. If misfire codes come back after the ignition parts are renewed, carbon on the valves and injectors can be the cause. Have it scanned before the next part goes in.
Notice fuel use on a car that barely moves. Fuel use going up on a Bentley that does few kilometres is one sign of intake valve carbon. Treat it as a reason to book, even if it still drives well.
Listen to the handover on a Bentayga Hybrid. Roughness as the petrol engine takes over from the electric side can point to light-load deposits. These cars are new enough that prevention still makes sense, so act on it early.

Book your Bentley in

Get a free quote

Tell us the model, the kilometres and what it is doing. We will scan it and tell you which clean it needs, and what it costs, before any work starts.

Get a Free Quote Call Nas — 0455 455 644