A question we are often asked both by first time buyers or already seasoned owners, “which Porsche is the best to purchase”. Throughout their history, Porsche has made outstanding vehicles. Excellence in engineering, styling, materials, workmanship and performance have been their core values from the very beginning. Their continual reengineering, technical and racing development has allowed Porsche to maintain a reputation as one of the top automotive manufactures in the world with some models that could be taken from the showroom directly to the race track. Which one is the best? The simple answer is Porsche’s latest offerings, the technology and performance are spectacular. However, that is usually not the answer being sought, the question really being asked is “which used Porsche is best for me.” That can be a very complicated answer on multiple levels as it goes directly to why we buy pre-owned automobiles and how we should buy them.
When considering a purchase of any pre-owned vehicle, there are multiple important questions that you need the answer to. The first is how has the car you are looking at been repaired, serviced and maintained? The second is what are the inherent issues with this year and model vehicle? Your goal should be to find the vehicle in the best possible condition so that you avoid expensive repairs.
When a vehicle leaves the manufacturing facility every component is new. Once sold the owner(s) decide if the vehicle is or is not properly maintained. Often, we meet owners that drive their car only occasionally, or short distances and some believe service need not be performed at normal intervals because the car is not driven that much, actually the car needs service more often in this scenario. We also see owners that drive excessively high or hard miles between services, oil deteriorates due to oxidation and combustion byproduct buildup in the crankcase oil, this diminishes the lubricating ability of the oil and raises internal component wear significantly. Neglecting the proper maintenance of the car causes the need for major mechanical work far earlier in the life of the vehicle than it should be. One thing you can count on, whether the car is maintained properly or not, most cars will be offered for sale, which would you prefer to buy?
People generally buy Porsches because they want the high-performance capabilities these vehicles provide and they typically utilize that performance often. This is another reason why maintenance is so important. You’re looking to buy a good car, but are you willing to pay the price to fix problems caused by the previous owner’s neglect? Too often, the owner did not understand, care or was not willing to spend the money to properly maintain their car. Give that some thought.
The unfortunate truth is that today many owners treat their vehicles like an appliance, they drive it until something breaks, not a good idea with any Porsche. What can you do to protect yourself when purchasing a pre-owned Porsche, start with asking to see the documented maintenance and repair history of the vehicle going back to when the car was first purchased. To some people this may seem extreme, however it is really the way to know that you are looking at a car that is everything it should be or not. The documentation will provide you with the answers to what was done, why and when for the Porsche in question. Many people tell us that there was no documentation but the CARFAX looked good. We feel that CARFAX provides some good data points, like accident identification, title issues, possibly the number of owners through title transfers, but that said, not all vehicle service companies report to CARFAX. Always get the CARFAX on a car you are serious about as part of your due diligence but it is not the substitute for minimal or no documentation.
We also hear about the cars with no service records that are or were owned by a mechanic, where they performed the service and repairs on their own car. One thing true mechanic’s do is save receipts so they should at a minimum provide you with receipts for parts and fluids purchased for that work. Many mechanics (and enthusiast owners) also keep spreadsheets of when and what work they and others performed on the car.
The real problem is when there is little to no documented history available for the car. We suggest this should be considered a BIG RED FLAG. You often hear the adage, “don’t get emotional when you are purchasing a car”, this is that moment. When we are delivering the bad news on what repairs the car needs to a new owner following their purchase; we too often hear “the car was so clean and the owner (or sales person) said they were sure the car was well taken care of. In these situations where little or no documentation of the car is available, we would suggest that it may be best to walk away, don’t roll the dice or take the chance, don’t believe the stories or excuses. Instead, find a good car with a documented history, this may take a while, but it will be worth the effort to get a good car. Remember when you go to the sell the car someday, the prospective buyers will be very surprised, and happy when you show them the folders of documented service repair history.
Once you have inspected the history, if it meets the qualification of documentation, your choice for options, colors, etc., and you are seriously considering that specific car; you should have the car inspected by a real Porsche mechanic as part of a Pre-Purchase Inspection (PPI). The mechanic must be very familiar with the year and model car you have found. The mechanic will give you data points regarding any current wear and tear, issues and what you might expect in the future based on condition, age and mileage. Remember that wear and tear issues are normal as the age and miles add up, electrical and mechanical devices wear out and need repairs or replacement. Many perspective buyers utilize the PPI as a way around the lack of service and repair documentation, but that will still leave a serious gap.
We can determine a lot of information by looking at and testing the car. Expect to spend $500.00 to $700.00 for a good visual check over and a basic interrogation of the Electronic Control Unit (ECU) that will identify the engine overrevs (starting with the 9X6 and newer models), system faults and most obvious issues. The technician will drive the car, check the operational condition of all the systems and note where something is improperly or not functioning.
You can also consider a much more detailed approach to the PPI that would involve a multiple day check over. This is where the technician approaches the car like a forensic analysis, where many areas of the car are inspected in detail and a much wider range of conclusions can be obtained. Rodent damage of the wiring, poor quality previous repairs, inappropriate aftermarket components parts, loose critical fasteners, suspension issues, chassis/ body repairs or safety related concerns. Additionally, specific engine testing including compression and leakdown tests, borescope inspection for cylinder scoring, metal debris in the engine, camshaft drive wear and deviation or chain tensioner conditions. Detailed interrogations of the ECU will reveal the computers first in service date which should match the build date of the car. This is Important to know, if the ECU in service and vehicle build date do not match this could be because a previous owner was trying to hide problems like engine overrevs or the POSIP computer for air bag deployments which once recorded cannot be erased. We can do engine and transmission / gearbox oil analysis which will give us insights into current fluid conditions and wear metal levels (to help establish a longer-term history of neglect where very high levels of wear metals are present). Areas of the car can be accessed that are not normally seen (like inside fenders or below coverings, etc.) to check for unrepaired or improperly repaired accident damage. Perform a suspension alignment analysis for unusual settings to hide previous chassis damage issues. You can expect to pay $2,000.00 to $4,000.00 or more (depending on the model) for this type of extremely detailed type of PPI assessment.
Many vehicles have inherent issues where changes did not work well or as expected. Certain year and model Porsches that you may be considering for purchase could or do have these issues and you should be aware of these before purchasing the potential problem. These are not general wear and tear issues related to age and mileage, however age and or mileage often exacerbate the problem. Typically, these are design issues or issues causing common failures with specific year(s), model(s) or series vehicles. Some of these issues can be solved relatively easily with repairs, updates or treating them as preventative maintenance issues where the offending part is replaced on a time or mileage interval basis before a failure can occur. It also must be stated that some of these types of issues, if not addressed before a failure occurs, can result in everything from the car not passing state mandated emissions retirements to an engine failure or even an electrical fire.
The M96 and M97 Engine IMS Bearing Issue
The M96 engine series was officially utilized in the 986 Boxster models from 1997 through 2004 and the 996 Carrera models from 1999 through 2004. It should also be stated that the M96 engine was carried over to the 997-1 Carrera and 987-1 Boxsters in 2005 and even into some 2006 models. So, it is possible that if you have a 2005 or an early 2006 Carrera or Boxster it may have come equipped with the M96 or the later M97 engine and unfortunately you cannot tell by the engine numbers. The 2006 987C Cayman should have the M97 engine but a real early production might not. Definitely the bulk of the 2006, and all 2007 and 2008 Carrera, Boxster and Caymans had the M97 engine. For the purpose of this discussion, it is important to know that the engine versions utilized in the 996 & 997 Turbo models, the 996 & 997 GT3 and GT3-RS are a different engine design and do not have the same internal problems as those engines in other afore mentioned Porsche Sports Cars.
By now many Porsche owners and followers have heard of the IMS (Intermediate Shaft) bearing issues associated with the Porsche 996 & 997 Carreras and the 986 & 987 Boxsters plus the 987C Cayman models, however, unfortunately many buyers have never heard of this issue. The IMS Bearing is part of the IMS Shaft, this shaft is chain driven from the crankshaft and the IMS shaft supplies rotational drive for the camshafts in the right and left bank cylinder heads. On each end of the IMS shaft there is a bearing that connects the shaft inside the engine case. The front of the engine (where the serpentine drive belt is located) utilizes a plain bearing that is supplied with engine oil from the oil pump, this IMS bearing never has a problem. The IMS bearing at the rear of the engine case (where the transmission connects) is a ball bearing design that is a sealed unit filled with grease for its internal lubrication. As wear takes place, the seal on the IMS bearing starts to allow small amounts of engine oil into the bearing, the oil destroys the viscosity of the grease yet because of the seals, not enough engine oil can get into the bearing to properly lubricate it. After the loss of grease lubrication, the bearing will start to wear at an accelerated rate until it reaches the point where the bearing literally comes apart which causes the engine to lose cam & valve timing control thus allowing the pistons and valves to make contact with each other resulting in a catastrophic engine failure.
Over the life of the M96 & M97 engines there were three versions of the IMS bearing utilized. These are the small diameter dual row bearing which was utilized in the M96 engine for the Boxster from 1997 through 2001 and the Carrera from 1999 through 2001. Next, a small diameter single row bearing was utilized in the M96 engine between 2002 and 2004 for the Carrera and the Boxster. The last was a large diameter single row bearing that was installed in the M97 engine, some from 2005, but all from for 2006 through 2008. The small diameter dual row bearing held up well but can still fail, the small single row bearing fails most often, the large single row bearing (M97) failed less often than the small single row but it still also can fail. A common question is how many engines have failed. During a Class Action lawsuit brought against Porsche by US owners on this subject in 2014, Porsche admitted that they had replaced somewhere around 10% of the engines in vehicles under factory warranty. Porsche does not have documentation for failures of IMS bearings outside of their warranty replacements.
There continues to be many misunderstandings about the seriousness of this problem, some people have suggested that the problem goes away as the engine gets older, actually the exact opposite is what really happens. The higher the mileage the higher the risk, but we have seen failures on engines with as little as 10,000 miles on the car. This is the primary reason the 986 Boxster, the 987-1 Boxsters and Caymans, 996 and 997-1 Carreras are priced so low, many people believe they are bargains but in the long run they are risky. There is a product called the IMS Solution available from LN Engineering which can be installed into an original 996 and 986 version of the M96 engine (in good condition) which will save the motor from this IMS bearing failure. Prior to the installation of the IMS Solution, the engine must pass an IMS Pre-Qualification Test to ensure that the engine is still in good condition. There is no metal debris inside the oil filter or oil sump plate (the oil pan) which could consist of ferrous or non-ferrous metal, plastic and or rubber debris, little or no camshaft deviation (position of the camshafts vs the crankshaft) and no Cylinder Bore Scoring (more on that below). Note, if the M96 engine had been previously replaced with a Porsche remanufactured engine the IMS Bearing might not be replaceable due to the use of a larger diameter M97 bearing that cannot be extracted from the engine case without engine disassembly. Like the later Porsche remanufactured M96 engine’s, some of the 2005 and most all of the 2006 997-1 and 987-1 engine’s up through 2008 model year can only have the IMS Solution upgrade installed during an engine rebuild. The only way to know which IMS bearing your engine has is to have it inspected by an LN Engineering IMS Solution Certified Installer. The IMS issues continued until Porsche’s introduction of the MA1 Series engine in 2009 where Porsche did away with the intermediate shaft completely.
These same M96 and M97 engines with the IMS bearing problem can also have other problems such as cracked and failed cylinder heads. This is brought on by a water pump design issue. The water pump impeller is made of plastic and over years if sitting in coolant the plastic impeller blades harden and start to break off. These broken pieces of plastic then circulate through the engine cooling system and can get stuck in the smaller coolant passages inside the cylinder head. With the coolant flow being impeded by the stuck plastic a localized hot spot develops and over time this excessive heat causes the cylinder head to crack. The head must be removed, repaired or replaced. In 2009 with the introduction of the MA1 engine series, the water pump design was changed and this was no longer an issue.
The engine can also fail due to internal bore scoring of the cylinder walls. Bore scoring is a complex issue with many contributing factors including the use of poor-quality fuels and engine oils, extended time intervals for oil changes, damaged or worn-out fuel injectors caused by the use of caustic ethanol blended fuels. The engine design also plays a role which occurs due to the non-supportive open deck engine design of the M96 and M97 engines. The open deck design allows cylinder ovality wear to take place. The cylinders actually wear into an oval like shape, no longer perfectly round, this cannot be easily seen but it can be measured. Typically, this wear problem takes place at the very bottom and or sometimes the very top the piston travel inside the cylinder. Once the ovality wear is present the piston rings are no longer making even contact with the full inside diameter of the cylinder wall. The piston can then pitch at angles, back and forth, thus allowing the piston skirt to make contact with cylinder wall and the aluminum piston skirt rubs directly against the aluminum cylinder wall resulting in deep scratches into the wall surface plus accelerated wear. This process will continue and get worse over time. An engine with bore scoring will have symptoms. When the engine is operating there will be a tapping sound which is often misdiagnosed as a bad hydraulic valve lifter that is not holding oil pressure. This tapping will speed up or slow down with the engine speed. The engine will also consume excessive amounts of engine oil because the piston rings to cylinder wall contact is compromised. The engine oil burning will also cause blue smoke from the exhaust and one or both exhaust tailpipes will have a black sooty burnt oil appearance. The oil consumption will become excessive and lead to oil-soaked spark plugs, misfires causing the Check Engine Light to illuminate. These problems can only be overcome by rebuilding or replacing the engine, unfortunately the cost for a proper engine rebuild will typically exceed the value of the of the car. It should also be noted that this problem is not present with the GT1 based engines used in the 996 and 997 Turbo and GT3 models.
Secondary Air injection and the 993
The 993 Porsche Carrera models have an issue called Secondary Air Injection (SAI) which happens to all model years (MY) 1995 through 1998. This problem is caused by cylinder head valve guides that wear out prematurely. The resulting oil that gets past the worn valve guides will burn and become hard carbon deposits due to the high heat around the exhaust ports of the cylinder heads. This burnt oil coating and will block the secondary air injection ports of the SAI system causing the system to stop functioning properly. The real problem is with MY 1996 through 1998 due to the United States requirements that On Board Diagnostics 2 (OBD-2) was implemented, if SAI is not functioning the car will set a Check Engine Light (CEL) and the car will not pass a State mandated emissions test for license renewal. To properly repair the problem the engine needs a top end rebuild valve job at the minimum using high quality (Non-Porsche) valve guides. High mileage cars (100K miles plus) that have not had the work will likely need additional repairs. It should be noted that the 1995 Carrera model will not set a CEL for SAI. This because it operates on OBD-1 and will not set the check engine light due to a nonfunctioning SAI system but it still has the same problem as its later year model version. Also note that the 993 Turbo utilizes a different valve guide material which is better designed to hold up under the added heat provided by turbocharging and which does not suffer from the pre-mature wear issues of the normally aspirated Carrera models.
The 964 during MY 1989, 1990 to mid-year 1991 did not come with cylinder head gaskets and as a result the heads leak oil, some severely. Porsche fixed the problem in 1992, as a result, by now most early 964 models we see have been corrected following an engine rebuild where the gaskets, machine work or replacement of the pistons and cylinders was performed. However, every once in a while, we see one which has not had the work done, usually very low mileage examples.
3.2 Liter Carrera
The 1984 through the 1989, 3.2-liter Carrera is one of the best factory Porsche models ever made. Only trouble is that they are getting old and the mileage has added up, it is difficult to find low mileage examples but they are out there. They are the first model to utilize the Carrera hydraulic engine chain tensioners, plus the 1987 through 1989 are the most sought after due to the addition of the G50 Gearbox with the hydraulic clutch, a very good upgrade. We must mention that the early and later Carrera models can have premature valve guide wear issues and suffer from head stud failures. Head studs should always be checked during a PPI to insure all are in good condition
Model years 1978 through 1983, very good cars, hard to find in good condition unless well cared for. There are many upgrades needed for these cars. Carrera hydraulic chain tensioners, pop of valve (for CIS fuel injection backfires), an oil cooler to should be added, head studs should also be checked during a PPI.
1975 through 1977 911s
Introduction and usage of the thermal reactors (prior to catalytic converters) that would get very hot and burn the hydro carbons in the exhaust. This made the engine’s run very hot and caused valve guide damage. This engine utilized a magnesium case and there were serious head stud issues where the studs pulled out of the engine case (instead of breaking). Porsche utilized a 5-blade fan which also did not cool the engine as well as the 11 blade fan. Engines typically did not last long due to hot running. 1976 and later still require California emissions testing every two years. Generally, these model years are not often seen today. Be careful buying one, could be tricky. Rust issues also of concern.
1974 911 and earlier.
From the factory the engine utilized a poor-quality mechanical chain tensioner. The tensioner could fail and cause a loss of valve timing. By now many of these engines have been rebuilt and updated to the Carrera hydraulic chain tensioners. Watch for wear & tear, accident damage, rust issues, failing materials due to age and poor maintenance.
If you have owned a Porsche you have experience with high cost to maintain and repair these cars. If you are a first time Porsche buyer you are venturing into the ownership of a used exotic performance car. Our best advice is to purchase a car in the best condition you can find with a well-documented lifetime of service and repair history, get the color(s) you love and have the car thoroughly inspected prior to your purchase. Don’t buy the bargain priced car, it is likely worse than you can imagine. Most owners have to take their car to a track or driver training program through a car club like Porsche Club of America (PCA) where you can drive the car on the track to really understand the depth of engineering these cars possess. If you still ask which Porsche should I buy, a 2009 or newer car with the proven MA1 engine, my choice is a 991 Turbo S because that level of performance will impress anyone. Good luck and happy hunting.
Enjoy Your Porsche!