Also known as: b4204s, b4194s, b6304, b6294, b6284, modular four volvo, modular six volvo, b6294t, b6304t4, b4164s, b4184s, b4194t, b4164t
Volvo's modular petrol engine in its four- and six-cylinder forms — the 2.0 B4204S in the S40 and C70, the 2.9 and 3.0 B6304 in the S80 and S90.
They are one architecture with a different number of cylinders, and the five-cylinder version — the white block that most people mean by a Volvo engine — has its own page here. All three share their bore spacing, their head design and most of their faults, so results from the five usually apply.
The recurring items are ventilation and ignition. The crankcase ventilation system blocks, pressurises the crankcase and pushes oil past the seals — the classic Volvo oil leak, and it is a maintenance item rather than a failure. Ignition coils fail one at a time.
The timing belt is an interference design and drives the water pump; on the six it is a longer, more expensive job than the four, which is worth stating before a quote is given.
The B6304T turbocharged six in the S80 is a different proposition from the naturally aspirated engines and its boost plumbing is where its own faults live.
Cars fitted with this engine
6 generations, across 1 make. From the authored catalogue — an absent car means the catalogue has not reached it, not that the engine was never fitted.
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Posted about this engine
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about B4204S / B6304.