IsItAGoodCar
Reliability Guide

Common Problems with the
2004 BMW 6 Series (E63/E64)

The E64 convertible joined in February 2004 and the 630i six arrived that August, giving UK buyers a cheaper coupé and a soft-top. The 630i came with a six-speed manual or automatic but no SMG.

What changed for 2004

  • •E64 convertible with a fabric roof and integrated wind deflector
  • •630i with the 258PS N52 straight-six added in August 2004
  • •Convertible gains pop-up rollover bars and a heated glass rear window

Common MOT watch-outs

  • !Convertible roof sensors and hydraulic leaks stopping the cycle
  • !Water in the boot and rear footwells from blocked roof drains
  • !Rear tyre wear and kerbed 18-inch alloys
4
Known Issues
2
Serious
2
Moderate
0
Minor

All Known Issues

V8 Coolant Pipe Leak (N62)

SeriousCooling System

The front rubber seal on the aluminium coolant crossover tube in the engine valley degrades. Coolant leaks through the weep hole in the timing cover. While BMW specified engine removal, aftermarket collapsible/telescopic tubes allow in-situ repair.

Est. Repair Cost: £800–£3,000
Warning Signs:

Coolant dripping from the small weep hole behind the water pump, Low coolant level warning on iDrive, Sweet coolant scent after parking

What to Inspect:
  • Shine a torch behind the water pump pulley to look for dried white or blue coolant tracks
  • Ask if a BimmerFix or All-Trac expanding stent pipe has been installed
Verified by IsItAGoodCar Research TeamUpdated

Valve Stem Seal Leak (N62)

SeriousEngine

The valve stem oil seals on the 32-valve N62 V8 bake hard from high operating temperatures (105°C thermostat), allowing engine oil to run down the valve guides into the combustion chambers.

Est. Repair Cost: £1,500–£3,000
Warning Signs:

Plume of blue/grey exhaust smoke when pulling away after idling for 5 minutes, Heavy oil consumption exceeding 1 litre per 800 miles, Fouled spark plugs and catalytic converter degradation

What to Inspect:
  • Idle the warm engine for 5–7 minutes, then rev to 3,000 rpm and observe exhaust
  • Check MOT emissions history for borderline HC levels
Verified by IsItAGoodCar Research TeamUpdated

Convertible Roof Sensor Failure

ModerateBodywork & Rust

On the E64 convertible, the complex electro-hydraulic roof mechanism uses multiple hall sensors and microswitches that fall out of calibration or break, halting the roof mid-cycle.

Est. Repair Cost: £200–£800
Warning Signs:

Roof stops moving midway through opening or closing, "Top not locked" warning on instrument cluster, Vertical rear heated window fails to drop or raise correctly

What to Inspect:
  • Operate the roof through two complete open and close cycles
  • Inspect hydraulic fluid level in boot pump reservoir
  • Check rear parcel shelf microswitch for positive latching
Verified by IsItAGoodCar Research TeamUpdated

Alternator Bracket Oil Leak

ModerateEngine

A figure-8 shaped rubber seal behind the engine-mounted alternator bracket hardens and leaks engine oil under pressure. Replacing the inexpensive seal requires significant front-subframe or engine-mount clearance.

Est. Repair Cost: £500–£1,000
Warning Signs:

Heavy engine oil leak on the front left (passenger side) of the engine, Oil dripping onto the steering rack and lower undertray, Burning oil smell while stopped in traffic

What to Inspect:
  • Inspect the underside of the alternator for fresh engine oil coat
  • Check left-side front suspension arms and subframe for oil contamination
Verified by IsItAGoodCar Research TeamUpdated

Buying Tips for 2004 BMW 6 Series (E63/E64)

  • Open and close the roof twice and watch for hesitation or warning chimes
  • Lift the boot carpets and check the hydraulic pump area for fluid
  • On a 630i, confirm the manual gearbox is not graunching into second
20032005–2006
Check a 2004 BMW 6 Series (E63/E64) by Registration