940 / 960

1990-1998 / Sedan / Estate / Sweden

All 940 / 960 problems All workshop issues

Critical Engine

B6304 (960) head gasket and overheating

Symptoms

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.

Cause

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.

Fix

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.

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// More 940 / 960 problems

Other known issues

Critical Engine

Oil leaks everywhere

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.

Common Engine

Flame trap and PCV system clogged

Engine bogs down, idles rough, struggles to rev, or won't start when hot. You might get excessive crankcase pressure, blowing out seals and pushing oil into the intake.

Critical Engine

Rough idle, hesitation, or won't start (fuel system issues)

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.

Critical Engine

Timing belt and waterpump failures

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.

Common Cooling System

Radiator, hoses, and expansion tank cracking

Coolant leaks, overheating, or sudden loss of coolant. The plastic expansion tank often cracks at the seams or where hoses attach. Radiator end tanks can split.

Minor Cooling System

Heater core and HVAC issues

No heat, weak heat, or coolant smell in the cabin. Sometimes the blower motor stops working or only runs on certain speeds.

View all 24 940 / 960 problems