Porsche 911 996 Mechanical Gremlins
It’s been well known for its issues around reliability, but 25 years on, what’s the real-world assessment of the 996’s mechanical underpinnings?
Porsche built over 175,000 996s, and if you believed everything you heard about it, every single one is problematic. The 996 has issues, but they’re hugely blown out of proportion. The effect is exacerbated by both the information revolution and the increased production proliferation. As Mark Sumpter from Paragon says, “The 964 had problems: the flywheel, the leaks. With the 996 it was about its timing. All of a sudden [online] forums existed. With a 964’s problems you had to speak to someone in a pub about it, or go to a dealer or a car club. With the 996 there were a lot more cars, and with forums one car with problems would be massively overblown. It was nowhere near as big a problem as people thought.”
“It”, of course, being the IMS (Intermediate Shaft) bearing. It’s impossible you’ll have read anything about the 996 and not heard of the IMS, and likely read the horror stories of lunched engines where IMS failure has resulted in valves meeting pistons, to engine-killing effect. We’d be lying to say it’s not an issue, but it’s one that’s significantly exaggerated, and a sizeable number of the cars you’ll find on sale now have had remedial work done to prevent it – doing so costs around £2,000. It’s also worth noting that it’s only applicable to the Carrera’s engine, not the Mezger unit that features in the GT3/RS and Turbo, and it’s more common in the earlier 3.4-litre cars, although it does occur with the 3.6-litre, too.
We regularly speak to Porsche specialists about IMS failure and 996s, and the usual response is that it’s rare these days. As Pete Twyman from Paragon’s Service department says: “I guess we’re lucky that we see very well-kept examples, but I’ve only seen one car here with IMS failure.” That statement underlines that a regularly, expertly serviced 996 shouldn’t be problematic. Mark adds “With the 996s being watercooled they have about half the amount of oil in them compared to air-cooled cars, which makes it more important that you change it regularly.” Sound advice, and a traceable, thick history file outlining money spent is the best preventative measure for future issues. And the IMS? The likelihood is it would have been a problem by now, and as the values continue to climb, that circa £2,000 outlay should you choose to replace it as a precaution, becomes a smaller percentage of the overall value of the car.
Other issues related to the 996 are the RMS – or rear main oil seal – that can leak. It’s not an expensive part to replace, but it’s a labour-intensive job. Consider replacing it if you’re going in for other maintenance such as a clutch replacement. Cracked cylinder heads and bore scoring is something else you’ll likely have heard about. This occurs where the cylinder’s Lokasil liners start to fail, causing the pistons to contact the cylinder wall. This causes poor oil lubrication that only exacerbates the issue. Cars that either have rarely run at temperature or often do short trips seem to be more likely to have problems thanks to localised overheating. If you’re buying it’s worth having a borescope inspection and the cylinder heads checked to make sure it’s not a problem with your potential purchase. Possible signs it might be an issue are rhythmic ticking, increased oil consumption, debris in the oil filter and particularly sooty exhausts, and jet-black used engine oil.
Keeping the radiators clear of debris will help prevent any overheating issues, even though doing so is a bumper-off task. Debris left in the radiators and the A/C condenser can cause corrosion. Likewise, make sure the coolant tank isn’t leaking, as they’re prone to doing. Replacements are expensive for Gen1 cars but not Gen2 bizarrely, if slightly fiddly to fit. At the other end, exhaust systems tend to be fine on the Carreras, with corrosion only really an issue around fixings. The biggest issue for Turbos is rot, and it’s worthwhile inspecting around the exhaust, silencers and turbos themselves regularly because they can rust quickly, even on relatively low-mileage cars. Now in its 25th year, the 996 has been through the worst of its depreciation dip, so be careful of cars that have been run on a shoestring when they’ve been bought for very little money. Prevention is always better than cure with Porsches, so keep on top of maintenance if you own one, and check if the owner has done so if you’re buying one.
Pete says he’s seeing more with corrosion around the shock absorbers. It’s the body of the shock itself, rather than the bodywork, with water getting trapped up by the bump stops and causing it. Rust on the body is unusual, although cars used all year round on salted winter roads will succumb to some corrosion. If you’re driving during the winter, make sure any salt is removed, and take preventative measures to protect underneath the car.
Brakes should need attention according to the regular service schedule. The brake lines can corrode, as will the backs of the discs if the car’s used infrequently and parked after washing. As ever, make sure the car’s fully dry before garaging it, to prevent any moisture causing issues when it’s not being used. Lack of use of any car is never good, so be sure to take it out regularly, and for a decent run to get everything up to temperature. Other areas of note are the coil packs that can fail (a misfire being a clue to this), while the suspension will need regular alignment, with replacement ‘coffin arms’. Doing so will make the car drive like new again.
Pete advises that when servicing, it’s best to do so with Porsche genuine parts; pattern parts are usually a false economy. The headlights fade, but that can be polished out and protected, while the gearboxes are pretty much bulletproof if they’ve had their scheduled oil changes, and clutches are strong, too. Don’t be frightened of the 996, then, because despite its reputation it’s not the basketcase that the internet would have you believe. We say buy one before everyone else reads this and realises what a brilliant car they’re missing out on.