BMW 740i Repair and Maintenance
A guide to problems, costs, maintenance and repair for your BMW 740i
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BMW 740i ProblemsCheck Engine Light with Code P30FF and Rattle from Engine
The BMW 7 series turbo engine suffers from waste gate issues which become progressively worse with normal driving and especially with harsh driving conditions.
The turbocharger uses exhaust gas to create air pressure which is then forced into the engine. When there is no demand for power, the exhaust gases are released into the exhaust through a waste gate to prevent the turbo from speeding up.
“Waste gate rattle” or “Turbo rattle” is a result of excessive movement between the waste gate and the waste gate seat. This is a progressive issue with the following symptoms:
- Rattling at cold start
- Rattling upon deceleration
- Loss of power
- Check Engine Light Illumination
- Manufacturer Specific OBD trouble code P30FF
- Very poor engine performance and MPG
Adjustment of the waste gate actuator can solve the issue, but the issue will return. If adjustment does not correct the issue, the turbocharger waste gate must be rebuilt with new bushings, or the turbocharger must be replaced. BMW has replaced many turbocharger assemblies under warranty to correct this issue.
Leaks are known to develop in the cooling system. It is common to see more than one part recommended for repair/replacement due to overlapping labor and the use of many plastic parts in the system.
A fluid leak may develop from one or more power steering hose. When a leak is being repaired, it is not uncommon for multiple hoses to be replaced.
BMW 740i QuestionsEngine misfiring on Bank 1 possibly due to timing problem. Could be timing guild (1 answer)
Replaced 20+ items on engine and it still runs rough as though it wants to stall out, it has left me stranded a couple times. The most likely problem is the timing chain rail is broken and maybe the tensioner and/or the gear and or vanos timing. Need to remove front of engine and replace problem...
The car has 223,000 miles on it and I have already replaced battery, water pump, and fuel pump.
BMW 740i RecallsThe Auxiliary Water Pump May Smolder and/or Catch Fire
On vehicles equipped with an 8 or 12 cylinder turbocharged engine, the circuit board for the electric water pump may overheat. This could lead to smoldering of the pump and/or an electrical fire in the engine compartment. Dealers will replace the auxiliary water pump to correct this concern.