Spot the grot
… and the expensive problems
elements. This is especially true of the brake, fuel, coolant and air-con pipes which run the length of the car. These are partly covered by a plastic undertray which is prone to gathering water, which then rots the steel pipes. Budget £200 to change the pipes that run the length of the car; £400 replaces all of the pipes. Choose between OE steel replacements (which will corrode) or copper.
The early cabriolet had a plastic rear window which fogs up. It can go brittle and split but it’s possible to fit the roof from a later 996 with a glass rear window. This means replacing the whole roof, but at £1200 all-in it’s not as costly as you might think. The soft tops last really well but for yearround use you can buy a used factory hard top for £500. If a cabriolet roof has leaked, water can get to the alarm control unit that’s under the front passenger seat, leading to the alarm setting itself off. A replacement control unit costs £1000.
Oily bits
One of the most serious potential issues is failure of the IMS (Intermediate Shaft) bearing, which can lead to complete engine failure. However, according to Zuffenhaus’ Mike Chare, while the costs to fix a failed IMS are high, the chances of the problem occurring are lower than the internet would have you believe. Anyone servicing the car should check the oil filter bowl for swarf, which is an early sign of the IMS having failed.
‘Intermediate shaft bearing failure is the most serious potential issue’
The IMS drives the camshafts and its bearing is sealed for life. The grease in the seal leaks out so it’s not lubricated properly, leading to failure of the seal and subsequently the bearing, which throws the cam timing out to the point that the engine is wrecked. Improved seals are available, but fitting them entails removing the gearbox and clutch. If the car needs a new clutch but is on its original bearing, it’s the perfect opportunity to fit an uprated part. At the same time the rear main seal (RMS) should also be replaced.
The RMS was a weak point on Porsches of this era with leaks not uncommon. Although the seal is inexpensive, labour is costly as it’s difficult to access. Fitting a 997 RMS is recommended as it’s much stronger.
A leak doesn’t always mean the RMS needs to be replaced immediately; it can sometimes be delayed until a bigger job needs doing, such as replacing the clutch. But once the RMS has failed, oil can get onto the clutch, wrecking it. Not what you want on a 911. Clutches tend to last no more than 50,000-60,000 miles, by which point the dual-mass flywheel might also need to be renewed. Budget £700.
Early 996s were 3.4 litres, enlarged to 3.6 from model year 2001. The latter has more torque but both are strong performers. The GT2, GT3 and Turbo have a different engine altogether, based on the GT1 competition unit, which doesn’t suffer the same problems. Cracked cylinder heads were a problem on
some 996s, but this is relatively rare; early 3.4-litre engines have proved much more prone to this than the post-2001 3.6-litre units. The engine’s cylinder liners can also crack, allowing the oil and water to mix. Cylinder bore scoring manifests itself as a light ticking noise at low revs and blue smoke from the exhaust. Badly scored bores will necessitate an engine rebuild.
Occasionally the oil separator on the top of the engine fails, allowing oil into the intake, and causing excessive blue exhaust smoke. It’s a cheap part but fiddly to change with the engine in situ. Don’t confuse problems here with the usual flat-six trait of the occasional small puff of oil smoke from the exhausts after a car has been sitting for a while.
The synchromesh can wear out on high-mileage manual-gearbox cars; it might also jump out of gear on the over-run if the gearbox has been abused. Tiptronic is reliable but make sure it’s had the oil and filter service, due at 12 years or 96,000 miles. This improves fuel economy and gear changes.
The diff bearings can get noisy on high-mileage four-wheel drive cars; changing the diff oil at 12 years or 96,000 miles will have helped reduce wear. It costs £1000 to rebuild a differential but used replacements can be picked up for half this. Swapping a diff over is an relatively easy DIY job.
The suspension is very effective and reliable, but the bushes don’t normally last more than 50,000 miles. Renewing them is costly as there are four per side at the rear and they’re around £100 apiece. Brake discs and pads are £400 for the front and £375 for the rear.
Trim and electrics
Light grey interiors look tatty quickly while some of the trim wears and gets readily scratched Ensure the air-con blows out refrigerated air; the frontmounted condensers rot out and replacing them costs £425. The plastic headlight lenses tend to go dull, but these can be buffed as good as new.
Don’t pay extra for a PCM sat-nav and stereo, as Porsche stopped supporting this years ago; a double-din aftermarket head unit can be fitted. From 2001 the units were upgraded to PCM II. These are more difficult (but not impossible) to replace.