All cars have problem areas, Boxsters are not exempt.
Not all Boxsters will have all problems, especially the first two which are limited to very early production and which, while serious, Porsche has owned up to.
1.
Porous Block Early '97 engines had a "porous block" problem that generally massively failed
within the first 10k. All are thought to have been replaced by now. The best description of this problem I know of is here.
2.
Slipped Sleeve Mid '98 thru early '99 engines had major internal engine slipped sleeve problems that
would cause total engine failure. Porsche replaced all the engines that
experienced the slipped sleeve problem under warranty (and many after
warranty). A replaced engine is a good thing as the replacement engines
have actually been more thoroughly tested than the ones put directly
into new cars. The best description of this problem I know of is here.
3. AOS "The air/oil separator is
essentially what was called a crankcase breather hose in earlier days.
It's simply a vent from the crankcase to the intake. In the past, the
crankcase was simply vented to the atmosphere releasing any volatile
pollutants directly into the air. Nowadays, the crankcase volatiles are
vented to the intake where they are burned in the cylinders. It's a
hydrocarbon emissions reducing measure. To reduce the sheer amount of
oil that gets drawn into the intake, they developed the air/oil
separator which is designed to condense the higher boiling components
and the oil mist (very fine droplets of oil that form when warm oil is
mechanically whipped up continuously like it is inside the engine) and
allow it to drain back into the crankcase.
There are two "failures" with the air/oil separators that I can distinguish. The first is simply a torn accordion looking tube (sometimes referred to as the "bellows tube") that goes from the crankcase to the bottom of the separator. This causes an oil leak and also a vacuum leak to the intake. The vacuum leak to the intake causes a lean running condition, which the ECU detects and adjusts to by enriching the mixture. Ultimately, the ECU maxes out its enriching ability and triggers a check engine light with the fault codes associated with enrichment limit: P1124, P1126, P1128, and/or P1130. (Note that this end result is general for any intake vacuum leak, not just the that caused by a torn AOS tube.)
The other failure mode is the failure of the air/oil separating ability of the separator. I don't know the exact nature of what happens in this case since I've never disassembled an air/oil separator. When this happens large amounts of oil can get sucked into the intake causing major oil smoke from the tailpipe. If this is allowed to go on long enough, spark plugs will become fouled, and I believe the catalytic converters could be permanently damaged. In the worst case scenario a cylinder could even fill up with enough oil to cause a condition known as "hydraulic lock" in which the piston now tries to compress an incompressible fluid in the cylinder on the compression stroke. The oil can't be compressed so something has to give, and kablooie... big problems."
contributed by Brett from San Diego
Symptoms of this last are typically huge oil clouds on startup or under hard acceleration, braking or cornering.
4. Heat Exchanger "The oil/water heat exchanger is simply a radiator-like device with oil and coolant flowing through separate but intimately contacting channels. When the engine is just warming up, the coolant will be warmer than the oil, so the coolant will transfer heat to the oil to help warm the oil faster. When the engine is at operating temp, the coolant will be colder than the oil, so the coolant will take heat away from the oil.
Reported failures of this part are rare, but it has been reported. If the internal passages fail, the oil and coolant will mix resulting in the appearance of a head gasket failure, when actually the problem is much cheaper to correct by simply replacing the oil/water heat exchanger (and of course flushing and replenishing the coolant and oil systems)."
contributed by Brett from San Diego
5 RMS (Rear Main Seal) wear exhibits itself as an oil drip.
Attributed to the design of the crankshaft and its supporting structure
as well as poorly designed seals. Porsche has provided at least 3
generations of parts and fix procedures. Said to be more common in
stick shift models than in Tiptronic-equipped cars. About $1000 to
repair. Repair consists of measuring the crankshaft hole and, if it is within specs, just replacing the seal with a new seal. If it is outside specs (crankshaft wobbles in the hole), then the suggested repair is engine replacement. You shouldn't pay for this yourself, it is a design flaw. Insist nicely but firmly your dealer contact Porsche.
Some cars have experienced multiple RMS problems. Porsche has
replaced some of the engines in such cars and in cars where their
measurement tool says replacement is the only option. Even out of warranty, they will sometimes buy the engine if you pay the labor.
6. Airbag Light Early Boxsters have a problem with seatbelt buckles not being grounded properly and causing an airbag light to be triggered. Replacement of the seatbelt or repair of the ground is the corrective action. There is a TSB #692450102.80TU and there is some chance that that TSB has been replaced with another one sometime in 2006. This can be a re-occurring problem, mine has been to the dealers 4 times with this symptom. Now appears to be fixed using the new procedure.
7. Top Cables Early Boxsters ('97-'99) have problems with the cables which operate the top frequently failing. Replacing with the newer style cables fixes the problem and is a do it yourself item. Instructions are available.
8. MAF Like almost all modern cars, the Boxster has a Mass Air Flow Sensor (MAF) in the air intake between the air cleaner and the engine that reports the amount and temperature of the air to the Engine Control Unit (ECU). This can get dirty. It throws a Check Engine Light up on the instrument display. How to clean it yourself in less than an hour for a total cost of about $30 (and save up to $690) is covered here.
9. O2 Sensors sit in the exhaust air stream and signal the ECU how it should adjust the air fuel mixture to achieve clean exhaust gases during startup. They wear out on any car. If it is just an O2 sensor going bad, they give off a very specific code
and can be easily and cheaply replaced by a do-it-yourselfer from instructions here. No reason to visit the dealers.
10. Supplementary Air Induction, etc. The Porsche Boxster engine uses complicated engine management sensors and electronics to achieve acceptable emissions, as do all modern cars. Problems in this area throw a Check Engine Light (CEL) onto the instrument display. Diagnosing what is wrong can get complicated and is best done with a Porsche System Tester 2 (PST2) and other specialized tools and access to the Porsche multi-volume Maintenance and Diagnostic Manuals. This area includes sensors, valves, tubing, blowers, etc.
11. Ignition Switch The ignition switch is prone to mechanical failure. It can be replaced with a $20 Audi part by a do it yourselfer who is young and supple. The dealers want several hours of labor and they are entitled to it as the job involves getting under the dashboard upside down and removing two screws that are devilishly hard to get at. I've read speculation that this is caused by too many heavy keys on the keychain.
12. Engine Mount The front engine mount deteriorates over time. A $196 list price part (PCA members get a discount at most dealers) and a do it yourself if you have access to a lift and the right tools or are exceptionally young or limber. Ask about Pedro's improved and cheaper re-manufactured mounts on www.ppbb.com.
13. IMS (Intermediate Shaft) affects mid '00 and following engines and is fatal to the engine. Is an internal engine failure.
toolpants on www.renntech.org posts: "The intermediate shaft is supported by a bearing on the rear of the
engine. This shaft drive things, like the cams via chains. The bearing
was a double bearing then Porsche switched to a single bearing. When the
bearing fails it damages the engine. I think this change was made in
2001.
You
hear a noise like marbles in a can then the engine stops. A nut on the
end of the shaft shears off which leave a hole in the back of the
engine for oil to pour out. It is too late for you to do anything."
Happens on a very small number of engines, no reported correlation between this failure and any maintenance, track, etc activity. Porsche is helping in situations where this occurs.
There was an excellent summary of early Boxster major engine problems including the first two here in the June 2007 issue of Excellence magazine.