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993 · 1996–1998 Air-cooled

1998 Porsche Carrera 4S

3.6 L flat 6 · AWD · Coupe · air-cooled

Power
285hp
Torque
251lb-ft
0–60
5.3s
Weight
3,175lb
lb / hp
11.1
Displacement
3.6L

Specification

US-market 1998
Power 285 hp
247 700
Weight 3,175 lb
2,910 3,640
Weight to power 11.1 lb/hp
4.6 lower is quicker 13.0

Where this car sits against every 911 in the catalog.

Engine
Engine code M64/21
Layout flat 6, air-cooled
Displacement 3.6 L
Aspiration Naturally aspirated
Power 285 hp @ 6,100 rpm
Torque 251 lb-ft @ 5,250 rpm
Redline 6,800 rpm
Specific output 79 hp / L
Chassis & body
Drivetrain All-wheel drive
Body styles Coupe
Transmissions 6-speed Manual · 4-speed Tiptronic
Curb weight 3,175 lb
Wheelbase 89.4 in
Length 167.7 in
Width 70.7 in
Height 51.8 in
Performance & market
0–60 mph 5.3 s
Top speed 168 mph
Weight to power 11.1 lb / hp
MSRP when new $73,000 base

About the 1998 Carrera 4S

1998Final year of the air-cooled 911. The 996 follows with water cooling and a very different reception.

Carrera 4STurbo body, Turbo brakes and suspension, without the turbochargers. The 993 most people picture, and the one values reflect.

Known issues

6 Specific to the Carrera 4S

Secondary air injection blockage

Major $1,200–$4,000
Affects

1996–1998 OBD-II cars. The 1995 cars predate the system.

What happens

Carbon and oil residue build up in the secondary air passages drilled into the cylinder heads. The system cannot pass its self-test at startup, the check engine light comes on, and the car fails emissions testing. Clearing it properly means getting at ports inside the heads, which is why a conceptually simple job turns expensive.

Symptoms
  • Check engine light with secondary air system codes
  • Failed emissions test with no driveability complaint
  • Light returns within days of being cleared
What to do

Cleaning the passages is the correct repair and it is labour-intensive. Beware a seller who has simply cleared the code before your viewing — ask when the light last appeared, and drive the car from cold.

Valve guide wear

Critical $8,000–$18,000
Affects

All 993, and the defining engine risk of the generation.

What happens

The valve guides wear and let oil past into the combustion chamber. It develops gradually over tens of thousands of miles and ends in a top-end rebuild — heads off, guides replaced, valves reground. On an air-cooled engine that is a serious bill, and it is the single most important thing to establish before buying.

Symptoms
  • Blue smoke on startup or after a long overrun
  • Oil consumption rising without an external leak
  • Smoke on hard acceleration after idling
  • Compression and leak-down figures spread unevenly across cylinders
What to do

No preventive repair. A leak-down test at inspection is the standard measure and is worth insisting on. Budget for a top end at some point in long ownership rather than assuming you have escaped it.

Oil leaks

Major $400–$4,000
Affects

All 993. An air-cooled engine that never leaks has usually just been cleaned.

What happens

Valve cover gaskets, chain housing seals, the oil return tubes and the crankcase breather all weep with age and heat cycling. Most are nuisance leaks; the ones that matter are those soaking the exhaust or the engine tinware.

Symptoms
  • Oil film on the engine tinware
  • Burning smell after a drive
  • Drips on the garage floor
  • Oil pooling in the spark plug wells
What to do

Trace it before replacing anything — the source is frequently higher than the drip. Valve cover gaskets are routine maintenance at this age; a chain housing leak is a much larger job.

Parts for this job

Varioram faults

Major $300–$2,500
Affects

1996–1998 cars with the variable intake system.

What happens

Varioram uses vacuum-actuated sliding tubes to change intake length. The vacuum lines perish and the mechanism can stick, costing mid-range torque. It rarely triggers a warning, so the car simply feels flat without anyone knowing why.

Symptoms
  • Noticeably soft mid-range with no fault code
  • Hissing from the intake area
  • Perished or disconnected vacuum lines visible at the engine
What to do

Vacuum lines are cheap and are the usual culprit. Verify the system actually switches before condemning anything expensive.

Parts for this job

Cracked exhaust manifolds and heat exchangers

Major $1,200–$4,500
Affects

All 993.

What happens

Heat cycling cracks the manifolds and heat exchangers. Beyond the noise, a crack can feed exhaust gas into the cabin heating system, which on an air-cooled car draws its heat directly off the exhaust.

Symptoms
  • Ticking or rasping that changes with engine load
  • Exhaust smell inside the cabin with the heat on
  • Visible cracking or soot staining at the manifold flanges
What to do

Replace the cracked component. Treat any exhaust smell in the cabin as urgent rather than as a character trait.

Parts for this job

Weak air conditioning

Minor $800–$3,000
Affects

All 993.

What happens

The system was marginal when new and is worse now. Age-related condenser corrosion and leaks turn marginal into ineffective.

Symptoms
  • Air conditioning that cools only at speed
  • No cooling at idle in traffic
  • System needing regular recharging
What to do

Uprated condensers and fans are a well-established upgrade path. Expect improvement rather than modern performance.

Parts for this job
Does not affect this car

Targa glass roof mechanism — documented elsewhere in the 993 range but not applicable to the Carrera 4S. See the generation overview for the full picture.

Service intervals

10
Item Interval
Engine oil and filter 5,000 mi or annually
Valve adjustment 15,000 mi
Spark plugs and ignition service 30,000 mi
Brake fluid 2 years
Fuel filter 30,000–40,000 mi
Air filter 20,000 mi
Transmission and differential fluid 40,000 mi
Clutch 60,000–100,000 mi
Valve cover gaskets As leaks appear
Secondary air passage cleaning On failure

What fits this car

30 Sizes, capacities and part specs

The answers you need when something has already failed — bulb sizes by position, wiper lengths, battery group, fluid specs and capacities. Sizes are for US-spec cars and are a starting point: options and mid-year changes move them, so check against your own car and its VIN before ordering.

Bulbs

9 The 993 uses a projector low beam rather than the sealed units of earlier cars.
Low beam H1 55W Shop →
High beam H1 55W Shop →
Front turn signal PY21W Amber. Shop →
Front position / parking W5W Shop →
Fog light H3 55W Shop →
Brake / tail P21/5W Shop →
Rear turn signal PY21W Shop →
Reverse P21W Shop →
Licence plate W5W Shop →

Wiper blades

2
Driver side 20 in Shop →
Passenger side 20 in Shop →

Battery

3
Group size Group 48 (H6) Shop →
Location Front luggage compartment, right side —
Minimum cold cranking amps 600 CCA —

Fluids and capacities

7 There is no coolant on this car. An air-cooled engine uses its oil for cooling as well as lubrication, which is why the capacity is so large and the interval matters so much.
Engine oil — capacity 9.0 qt with filter Check the level warm and with the engine running, per the factory procedure — not cold like a water-cooled car. —
Engine oil — specification 5W-50 or 20W-50, high-zinc Wants an oil formulated for air-cooled flat-sixes. A modern low-zinc oil is a false economy on this hardware. Shop →
Coolant None — air-cooled No radiators, no expansion tank, no coolant service. One of the genuine ownership advantages. —
Brake fluid DOT 4 Shop →
Transmission — manual 75W-90 GL-5 Shop →
Power steering Pentosin CHF 11S Shop →
Fuel tank 19.4 gal —

Wheels and tyres

7
Bolt pattern 5 x 130 mm
Centre bore 71.6 mm
Lug bolt thread M14 x 1.5
Tyre size — 17 in front 205/50 ZR17
Tyre size — 17 in rear 255/40 ZR17
Tyre size — 18 in front 225/40 ZR18
Tyre size — 18 in rear (wide body) 285/30 ZR18

Torque values

2 Safety-relevant. Verify against factory documentation before relying on these.
Wheel lug bolts 96 lb-ft (130 Nm) Star pattern, on the ground, calibrated wrench.
Engine oil drain plug 37 lb-ft (50 Nm) New sealing washer every time.

Fitment for the 1998 993 Carrera 4S. Torque values in particular are safety-relevant — verify against factory documentation rather than relying on this page alone.

Buying guide

7
  1. 01

    Leak-down test, not just compression

    This is the 993 equivalent of borescoping a 996. Valve guide wear is the generation-defining risk and a leak-down test across all six cylinders is how you find it before you own it. A seller refusing one has told you something.

  2. 02

    Drive it from stone cold

    Blue smoke on a cold start is the classic valve guide signal, and it disappears once the car is warm. A car already idling when you arrive is a car you have not yet inspected.

  3. 03

    Ask when the check engine light last appeared

    Secondary air faults are cheap to clear and expensive to fix, and the code can be reset the morning of a viewing. Confirm the car will pass an emissions test in its current state, in writing if you can.

  4. 04

    Some oil weeping is normal — soaked tinware is not

    Every air-cooled 911 seeps somewhere. What matters is where it comes from and whether it is reaching the exhaust. Judge the source, not the presence.

  5. 05

    The wide-body cars carry a real premium

    The Carrera S and 4S trade well above the narrow-body cars, and that gap has been stable for years. Whether the wide body is worth it to drive is a separate question from whether it is worth it to own.

  6. 06

    Records matter more than mileage here

    A 993 with 90,000 miles and a folder of air-cooled-specialist invoices is a better buy than a 40,000-mile car that has sat. These engines dislike sitting more than they dislike being driven.

  7. 07

    Budget for a top end eventually

    Over long ownership, assume valve guides at some point. Buying at a price that leaves room for that is the difference between enjoying the car and being trapped by it.

Parts and gear

15 Chosen for this car, not for the commission

What a Carrera 4S actually costs to keep, grouped by why you would buy it. Prices are typical US parts-only figures — labour is separate, and the DIY note says whether that matters. Where a link earns us a commission it costs you nothing and never changes what appears here.

Parts that fix a known problem on this car

4 Each one maps to an issue above
  • Engine $80–$300

    Valve cover gasket set

    The most common source of the weeping every 993 does eventually. Cheap parts, accessible job, and it makes every future leak easier to trace because you have eliminated the obvious one.

    FCP Euro → DIY or shop
  • Intake $60–$250

    Varioram vacuum line kit

    Perished vacuum lines are the usual reason a Varioram car feels flat in the mid-range. A cheap kit that restores torque nobody realised was missing.

    FCP Euro → DIY
  • Exhaust $1,000–$4,000

    Heat exchanger or manifold replacement

    The fix for cracks that put exhaust gas into the cabin heating. Expensive, and not a repair to postpone once you can smell it inside the car.

    FCP Euro → Shop job
  • Cooling $700–$2,500

    Uprated A/C condenser and fan kit

    The established fix for a system that was marginal when new. Sets expectations correctly: better, not modern.

    FCP Euro → Shop job

Worth doing before it fails

3 Cheaper than the repair it avoids
  • Engine $25–$60

    Magnetic drain plug

    Catches ferrous debris at every change on an engine where an early warning is worth a great deal. Cheap and permanent.

    Shop this → DIY
  • Ignition $150–$500

    Distributor cap, rotor and plug set

    Ignition components on an air-cooled engine live in heat that kills them early. A full refresh restores starting and idle quality that owners often assume is just how the car is.

    Shop this → DIY
  • Protection $40–$130

    Battery cut-off or tender

    These sit far more than they are driven, and a flat battery on a car of this value invites more problems than it solves.

    Shop this → DIY

Consumables you will rebuy

4 Ordinary running costs
  • Fluids $80–$170

    Air-cooled specification engine oil

    An air-cooled flat-six wants an oil formulated for it — heavier weight, high zinc content for the flat-tappet-era hardware. Around nine quarts a change, and the wrong modern oil is a genuine false economy here.

    Shop this → DIY
  • Fluids $20–$60

    Oil filter and sump hardware

    Bought with every change. Cut it open — on an engine this expensive to rebuild, the information is worth the two minutes.

    Shop this → DIY
  • Fluids $15–$60

    Brake fluid

    Two-year replacement, and the cheapest safety-relevant service on the car.

    Shop this → DIY
  • Service $40–$120

    Air and fuel filters

    Routine, cheap, and both are straightforward owner jobs on this generation.

    Shop this → DIY

Tools worth owning

4 Bought once, used for years
  • Inspection $60–$250

    Leak-down tester

    The single most important measurement on a 993, and the one that finds valve guide wear before you own it. If you are shopping several cars, this pays for itself on the first one you walk away from.

    Shop this → DIY
  • Inspection $30–$80

    Oil filter cutter

    Opens the filter so you can look for metal. Cheap insight into an engine whose rebuild costs five figures.

    Shop this → DIY
  • Lifting $150–$400

    Low-profile jack and jack pads

    The jack points are specific and unforgiving, and a crushed sill on a car of this value is an expensive lesson.

    Shop this → DIY
  • Storage $100–$600

    Car cover and climate control

    Most 993s are stored more than driven. Managing damp is how the interior, the electrics and the underside stay worth what the car is worth.

    Shop this → DIY