MajorCommonEngine

Alfa Romeo 156: Twin Spark cam variator rattle ('diesel' knock on start-up)

Twin Spark cam variator rattle ('diesel' knock on start-up) is a common engine fault on the Alfa Romeo 156 on the 1997–2005 cars, and we rate it major. Putting it right costs $600 to $1,800 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 5 documented faults on the Alfa Romeo 156.

Vehicle: Alfa Romeo 156
Years: 1997–2005
Fuel: petrol
System: Engine

This page covers the Alfa Romeo 156 as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Alfa Romeo 156 faults5 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the CVT belt and pulleys yet. We would rather show none than show a picture of a different part.

What goes wrong

The Twin Spark (TS) petrol engines use an oil-fed cam-phasing variator on the exhaust camshaft that wears and rattles as it ages, typically from around 80,000-120,000 km. Owners describe a loud diesel-like knock or rattle for a few seconds on cold start (oil drains from the unit overnight) that lengthens as it deteriorates, and rattling under load below about 1500 rpm. A worn variator loses top-end power, and if it disintegrates it can damage the cam and valvegear, so it is normally replaced together with the cam belt.

What you would notice

Loud diesel-like rattle or knock for a few seconds after a cold start
Rattle that lasts longer as the fault worsens
Metallic rattle under load below about 1500 rpm
Loss of top-end power and higher fuel use
Ticking or tapping from the top of the engine

How to check it

Where to look. Front of engine, exhaust camshaft variator behind the cam-belt cover, top of cylinder head

Do a genuinely cold start and listen for a diesel-like rattle from the cam cover area that clears once oil pressure builds; a long or persistent rattle points to a worn variator. Ask when the cam belt was last done and whether the variator was replaced at the same time, and check service records for it. Listen again at idle and on a test drive under light load below 1500 rpm. Around 80,000-120,000 km a car with no history of variator or belt work is higher risk.

Parts involved: CVT belt and pulleys.

What it costs to put right

$600 to $1,800 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

“When was the cam belt last changed, at what odometer, and was the variator replaced too?”
“Is there any rattle or knock when the engine is started cold?”
“Do you have receipts for the timing belt and variator work?”

Now check the Alfa Romeo 156 you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.

Alfa Romeo 156 buyer questions

Is twin spark cam variator rattle ('diesel' knock on start-up) serious on a Alfa Romeo 156?

We rate it major and common on the Alfa Romeo 156. The Twin Spark (TS) petrol engines use an oil-fed cam-phasing variator on the exhaust camshaft that wears and rattles as it ages, typically from around 80,000-120,000 km. Owners describe a loud diesel-like knock or rattle for a few seconds on cold start (oil drains from the unit overnight) that lengthens as it deteriorates, and rattling under load below about 1500 rpm. A worn variator loses top-end power, and if it disintegrates it can damage the cam and valvegear, so it is normally replaced together with the cam belt.

How much does it cost to fix on a Alfa Romeo 156?

$600 to $1,800 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Alfa Romeo 156 years are affected?

Our research records this fault on the 1997–2005 Alfa Romeo 156. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.