Are there any problems with the Porsche 991?
Though, there is one relatively common issue: faulty change over valves (COVs). Porsche 991 cars have multiple COV solenoids, each used to route vacuum to a different part of the vehicle (e.g., heater shut-off valve, exhaust flaps, etc.). Otherwise, owner reviews and online resources generally portray the 991 as a reliable car.
What’s the problem with the Porsche 966 engine?
Perhaps the most famous (or should we say, infamous) problem with the 966 is the weak intermediate shaft (IMS) bearing. The IMS shaft, which drives the camshafts, causes extensive (and expensive) engine damage when its bearing fails.
Can a bad IMS bearing cause a Porsche to fail?
Yes, be clear, the IMS bearing is a weak point and it will fail. However, in the real world less than 5% have actually failed or can be directly linked to an engine failure. Porsche shipped approx. 77,000 vehicles to the USA that could have a bad IMS bearing.
What causes the AOS to fail on a Porsche?
The AOS has caused numerous issues on Porsche engines. As the membrane in the AOS fails, oil is sucked into the air intake. Initially this can show up as a check engine light for fuel adaptations and the oil can be deposited on the o2 sensors causing emission faults.
Why did Porsche change the way they cast the engine?
Engine Casting Porosity: As mentioned in the previous section, Porsche used a new cost-effective method to cast most of the oil and water cooling passages directly into the engine case. This reduced the total part count for the engine and also helped reduce assembly time and production cost.
What happens when IMS bearing fails on Porsche?
When the bearing does fail, foreign object debris from the bearing circulates throughout the engine, causing further damage to other areas in the engine. On the early cars, Porsche also used a center bolt to secure the IMS bearing that was too weak and sometimes snapped.
Are there any mechanical problems with my Porsche 911?
Listed below are Porsche 911 common mechanical problems with their likely resolutions. These are the most frequent 911 problems diagnosed by our repair shops over the years. An accurate diagnosis of an issue by a Porsche mechanic typically saves you time and money – see our guide to local independent Porsche repair shops that can help.
The AOS has caused numerous issues on Porsche engines. As the membrane in the AOS fails, oil is sucked into the air intake. Initially this can show up as a check engine light for fuel adaptations and the oil can be deposited on the o2 sensors causing emission faults.