940 / 960

You'll find oil pooling under the car, dripping from the valve cover, front and rear main seals, cam seals, or oil cooler lines. The B230 engines (940) and B6304 (960) both weep oil as they age, it's not if, it's when.

Decades-old rubber seals harden and crack. Heat cycles accelerate the process. The valve cover gasket is often the first to go, followed by the front crankshaft seal. On high-mileage examples, the rear main seal starts leaking too.

Replace seals systematically. Valve cover gasket is a 30-minute job. Cam seal requires timing belt removal, do it when you're in there anyway. Front crank seal is straightforward with the belt off. Rear main seal means gearbox or engine removal, so assess whether the leak is bad enough to justify the labour. Use OEM Volvo gaskets, aftermarket ones often don't seal properly.

Stumbling acceleration, poor fuel economy, hard starting, or stalling. Sometimes it runs fine cold but misfires when warm. Check engine light may be on or flashing.

Fuel injectors gum up, fuel pressure regulator diaphragms leak, or the fuel pump weakens. The AMM (Air Mass Meter) on early 940s fails frequently, cleaning sometimes helps, replacement usually required. Ignition amplifier (ICM) failures are common and mimic fuel issues.

Start simple: clean the throttle body and idle air control valve. Test fuel pressure at the rail, should be around 3 bar (43 psi) with vacuum line disconnected. If low, suspect the pump or clogged filter. Replace fuel filter every 2 years regardless. Check injector spray pattern, if they dribble rather than mist, they're done. Replace in sets. For AMM faults, try cleaning the hot wire with electronics cleaner, but replacement is often inevitable. Swap the ignition amplifier if you have intermittent misfires, they fail when hot.

Catastrophic engine damage if the belt snaps. You'll hear grinding, the engine stops instantly, and you're looking at bent valves or worse. Waterpump failure shows as overheating or coolant leaks from the front of the engine.

Belts age and crack. Tensioners seize. Waterpumps wear out, the plastic impellers can disintegrate on early models.

Replace the timing belt, tensioner, and waterpump together every 100,000 km or 10 years, whichever comes first. Use a Volvo or Gates belt kit. Don't skimp on the tensioner. If the pump is original and plastic-impeller, fit a metal impeller replacement. Check the balance shaft belt at the same time (940 only). This is not a DIY job unless you're confident, a mistake means engine destruction.

White smoke from the exhaust, coolant disappearing with no visible leaks, overheating, or rough running. Sometimes you'll see oil in the coolant expansion tank.

The B6304 straight-six is more fragile than the B230. Head gaskets fail, often between cylinders or into the cooling passages. Overheating accelerates this, common if the radiator or thermostat is neglected.

Head gasket replacement is a big job. Budget for machining the head flat if warped. Fit a new thermostat, radiator cap, and flush the system while you're in. Bleed air from the system properly, run the engine with the expansion tank cap off until the thermostat opens and air bubbles stop. Some specialists recommend upgrading to the later multilayer steel (MLS) gasket, though availability varies.