Information you need to know

Model. When ordering parts it is important that you know the correct model designation for your car. Models covered in this manual are 911 Carrera coupe, targa and cabriolet configurations.

Model Year. This is not necessarily the same as date of manufacture or date of sale. A 1986 model may have been manufactured in late 1985, and perhaps not sold until early 1986. It is still a 1986 model. Model years covered by this manual are 1984 to 1989.

Date of Manufacture. This information is helpful when ordering replacement parts or determining if any of the warranty recalls are applicable to your car. The label on the driver's door pillar (arrow) will specify the month and year that the car was built.

Vehicle Identification Number (VIN). This is a combination of letters and numbers that identify the particular car. The VIN appears on the state registration document, and on the car itself. One location is in on the left windshield pillar, another is on the luggage compartment lid (arrow). The sticker on the luggage compartment lid contains the following information:

1. Vehicle Identification Number

2. Vehicle code

3. Engine and transmission code

4. Paint and interior code

5. Option Codes

A duplicate of this label is also contained in the vehicle's original paper work (Warranty and Maintenance card).

Porsche Engine Identification Numbers

As of 1987 model year, the National Highway Traffic Safety Administration (NHTSA) requires passenger cars with a high theft rate to have the VIN marked on specific parts of the car when manufactured. On Porsche cars, these parts are identified by an adhesive label bearing the VIN and Porsche script. Replacement parts have a similar label, bearing the letters DOT-R. These labels should not be removed as they will tear apart or painted over.

Engine number. The engine number is stamped on the left crankcase half, below the fan housing (arrow). 911 cars covered in this manual are powered by a 6-cylinder engine. For information on engine codes and engine applications, see 100 Engine-General.

Engine Numbers

Paint code. The paint code is on a sticker on the right fender inside the luggage compartment (arrow).

Hydraulic Clutch Reservoir 911 Porsche


Transmission. The transmission type with its identifying code may be important when buying clutch parts, seals, gaskets, and other transmission-related parts. Two transmissions were installed in the models covered by this manual, depending on model year.


with cable-operated clutch 915,5-speed manual

with hydraulic clutch operation G50 5- speed manual

The transmission number is an eight digit number, i.e. 73 G 349533

Digit 1 6-cyl. transmission (7)

3 Model year (G=1986) Digits 4 - 8 Serial number (349533)

For more information, see 300 Transmission and Clutch-General.


Porsche dealers are uniquely qualified to provide service for Porsche cars. Their authorized relationship with the large Porsche service organization means that they are constantly receiving new tools and equipment, together with the latest and most accurate repair information.

The Porsche dealer's service technicians are highly trained and very capable. Unlike most independent repair shops, authorized Porsche dealers are intensely committed to supporting the Porsche product. They share the owner's interest in Porsche value, performance, and reliability. On the other hand, there are many independent shops that specialize in Porsche service and are capable of doing high quality repair work. Checking with other Porsche owners for recommendations on service facilities is a good way to learn of reputable Porsche shops in your area.

Compression test

A test of compression pressures in the individual cylinders will tell a lot about the condition of the engine without the need for taking it apart. The test is relatively simple. It requires a compression tester, spark plug wrench, and a few hand tools.

To obtain accurate results, the battery and starter must be capable of turning the engine at normal cranking speed. The area around the spark plugs should be clean, to avoid getting debris inside the engine when the spark plugs are removed. Because engine temperature may affect compression, the most accurate results are obtained when the engine is at normal operating temperature.

Compression test

Disable ignition system and fuel pump by removing harness connector from DME main/fuel pump relay (2), located beneath driver's seat.

The ignition system produces high voltages that can be fatal. Avoid contact with exposed terminals and use caution when working on a car with the ignition switched on or the engine running.

— Remove heater blower elbow on left side of engine and air filter cover and filter element on right side.

— Remove and label spark plug wires.

— Remove and number spark plugs.

Used spark plugs should be installed in the same cylinder from which they were removed.

— Thread compression tester into cylinder no. 1 spark plug hole tight enough to seal hole.

— With parking brake set, transmission in neutral, and throttle held wide open, crank engine with starter. Crank engine for 4-5 full revolutions. Record value.

The gauge reading should increase with each engine revolution. The engine should be cranked an equal number of revolutions at each cylinder to obtain the most accurate readings.

— Remove gauge from cylinder no. 1 and release pressure from gauge.

— Repeat test for other cylinders. Record gauge reading for each cylinder.

— Compare readings from each cylinder. NOTE —

Removing the spark plugs may cause built-up carbon on the plug to fall onto the exhaust valve seat. If this happens, the exhaust valve may not seat fully, resulting in a low compression reading at that cylinder. If you suspect a partially open valve, reinstall the plug and run the engine at 2,500 rpm for about 1 minute. Remove the plug and repeat the test.

— Reinstall spark plugs and spark plug wires in their original locations. The remainder of installation is reverse of removal.

Tightening Torque

Low compression is evidence of poorly sealed combustion chambers. Generally, compression pressures that are relatively even but low indicate worn piston rings and/or cylinder

Valve Seat That Fell Exhaust Valve


walls. Erratic values tend to indicate valve leakage or a broken cylinder head stud. There are other tests that can further isolate the problem.

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