996
may have been the first water-cooled 911 but it certainly wasn't new territory for Porsche by then. The Boxster was already using a version of the new 911's engine, albeit with smaller capacities and mid-mounted. Porsche launched the 996 with a 3,387cc engine with four valves per cylinder that produced 300hp at 6,800rpm. This was increased to 3,596cc from 2001. The 3.4-litre engine offers 258lb ft of torque at 4,600rpm, while the 3.6-litre unit is a tad more flexible with 273lb ft at 4,250rpm. A six-speed manual gearbox was standard fit for the 996 in all body styles or buyers could opt for the five-speed Tiptronic auto with manual override.
Plenty new, but some things never change...
The gearboxes in the 996 are regarded as tough, but clutches can wear more quickly than you might expect on manuals, so check for any slipping or judders from a standing start. Early 996 manual gearboxes experienced a few woes with broken gear linkage cables, but this should have been sorted either under warranty or by a careful owner. Porsche modified the cables in 2001 to rectify this fault and the improved system can be fitted to earlier cars. The Tiptronic auto is also reliable, but make sure the car cycles through all five ratios smoothly and the manual function works cleanly and quickly with the kickdown.
Now we come to the two big areas of debate and concern with the 996: the rear main seal and intermediate shaft. The rear main seal (RMS) sits at the front of the engine on the crankshaft. When it begins to fail, oil seeps past and drips down into the gearbox bellhousing and on to the ground. In most cases, this is more of an irritation than a major problem so long as the oil leak doesn't get worse and you keep the engine topped up with quality oil. It will need replaced eventually, but it's an engine out job, so canny owners wait till the clutch needs replacing and have the RMS changed at the same time.
Early cars most afflicted by engine woes
A word of caution as the RMS needs to be properly positioned and seated with a special tool to make sure it doesn't start leaking again. An uprated RMS from Porsche is available to address the problem of the original failing and there are also upgraded RMS in ceramic from specialists.
While a leaking RMS is rarely fatal to the engine's health, the intermediate shaft (IMS) is a much greater worry. The IMS is driven off the crankshaft and operates the double overhead camshafts on each bank of cylinders. A sprocket on the end of the IMS drives the cams and is held in place by a small stud. This stud can break off and allows the IMS to wear the bearing that holds it in place.
The first signs an owner will notice of this problem is a rattle when starting the engine from cold. This will develop into a much worse rattle before the cam chain jumps off and destroys the engine. Porsche changed this design to use a larger bearing and toothed chain, but it's not possible to swap this into earlier engines. A rebuilt engine from a well regarded specialist such as Hartech or Autofarm will underpin the value of any 996.
Facelifted car remedied clutch cable problems
The IMS can also cause an oil leak at the front of the engine, which is buried under the rear window and can be easily mistaken for an RMS leak. When the IMS bearing leaks, it needs to be replaced and the securing bolts properly sealed in place to prevent future leaks. If you spot oil in the coolant when inspecting a 996, it's likely one or both of the cylinder heads have cracked, allowing oil into the water jacket.
The other crack to be worried about is with the cylinder liners. They are made of Lokasil and the aluminium block was cast around them to create a single unit. In most cases, it's the centre cylinder of the three on each bank that fails. It starts with a small crack appearing and this can lead to a chunk of cylinder liner detaching, which renders the engine scrap. The only sign this is happening is an increased thirst for coolant, so watch fluid levels carefully.
A replacement engine will be anything between £3,500 for a motor from a scrapped car up to £12,000 for a completely rebuilt unit from a specialist, and you will have labour charges on top. Checking the oil level is done with the dashboard digital display, so many owners overlook it. Also inspect the radiators at the front fully as, like the Boxster and Cayman, they corrode and can be damaged by stones.
RMS/IMS only affects about five per cent, honest!
996
is most likely to be the oil breather system failing. It can lead to a cylinder filling with oil and the engine refusing to start, but a modified breather is available from specialists that cures this ill. Other oil leaks can occur from the cylinder head gaskets and pipes in the engine bay, but they are no more or less common than with other performance cars of this age and era.
Poor idling is not uncommon and down to the VarioCam variable valve timing mechanism. Corrosion on the solenoid prevents the system working as it should, but is a relatively simple job to replace with a redesigned part from Porsche.
Despite these potentially catastrophic problems, experts reckon they affect only around five per cent of 996 production and earlier cars were more susceptible.
PHer's view:
About two months after buying it, my 996 started to smoke out of the left bank, which I thought was the dreaded piston lining wear. I looked around for a local garage in north London and found Jaz. Took it there and they had a thorough check and gave me quite an extensive list back with issues. However, there wasn't the dreaded piston issues. The smoke was all to do with a oil and water separation filter which was not doing its job.
Olivier Lauchenauer
