Back in the 1960s, I owned one of those small, cramped British sports cars and put up with the cold, rain and wind as these elements inevitably came into the car. I worked at a used car lot in the University District of Seattle that specialized in these sorts of cars and had the opportunity to work on, road test and dream of owning a number of different makes and models. One of the cars that I would never have dreamed of owning was an early Porsche; they were just too different, too much like an old VW, and just looked funny.
That was before the first 911 came out. What a difference that car was. With the 6-cylinder engine, lots of power and even a back seat — of sorts — that car would be on my top 10 list of cars I would most like to own. Even though I’ve never owned one, I’ve worked on, driven and developed opinions about the 911 Series and other Porsche models during the many years I’ve specialized in German-built cars.
There are, of course, many other models in the Porsche lineup: the entry-level 914, the 4-cylinder 912, and the water-cooled 924, 944 and 928, and others with front engines, water cooling and not much else to distinguish them from every other car in the world. The Carrera series continues to be the product leader, along with its mid-engine sibling the Boxster, the only true Porsches still available (just my opinion). Now there is an SUV (the Cayenne) and who knows, maybe a mini-van in the future?
The focus of this article will be the Carrera from the mid-1980s and Boxster models, as these are the cars that we see the most. Given that Porsche work is a very small segment of our business, there are many shops that have never worked on these cars.
Since the late 1980s, the Carrera has evolved into the very best of the high-performance sports car category. With the change to hydraulic lifters and more durable engine components, maintenance costs have gone down and driveability has improved. The Boxster provides a very affordable alternative to the Carrera in a modern, two-passenger sports car with some of the old-fashioned sports car feel remaining. Both models have been pretty reliable for our customers — those who maintain them properly, that is.
The term “air cooled” has always been a bit of a stretch for the 911 Series. In actual operation, the cooling of the engine in these cars is accomplished by oil-to-air intercooling through a large capacity oil system, and both engine-mounted and external heat exchangers. The big fan (see Photo 1) on the engine is used mainly for cooling the finned cylinders. The dry sump oil system is designed to move oil through the engine quickly to absorb as much engine heat as possible, and quickly transfer that heat to the air. A thermostat, much like in a water-cooled vehicle, controls oil temperatures and leaks can have the same effect with this system as in water cooling.
For these “air cooled” cars, the important part of maintenance is detecting and resolving oil leaks and keeping the fan running. Anyone who has worked with these cars for any length of time will tell you that oil leakage is a fact of life, but needs to be at least controlled. Since oil lines travel the length of the car, on the right side at the rocker panel area, care must be taken when putting these cars on a lift. Some later models also have the oil reservoir drain, auxiliary filter and thermostat housing located just in front of the right rear wheel, so care must be taken there as well. There are a number of rubber oil lines and fittings in the system that can also leak, so a thorough inspection, front to back, is important.
Some of these cars have two filters, located in different locations depending on engine type, and some are in difficult locations. Oil changes should include a complete drain of the reservoir system and the engine crankcase, and the correct refill and top-up procedure must be followed to make sure there is adequate oil for the system to operate correctly. These cars can hold from 10 to 13 quarts of oil, and knowing the exact model, engine size and oil capacity is important. The typical procedure for filling the oil system after the system is drained and filter(s) is changed goes as follows.
Add a minimum 9 quarts to the reservoir, start the engine and let it idle. Since the engine lid is open, be careful not to have loose items around the area, and be aware of the engine fan and belts (See Photo 2).
Allow the engine to idle, verify that engine oil pressure has come up to normal levels and pull the dipstick, which may be under the filler cap, or separate.
At this point, there will probably not be any oil on the stick or it will be slightly low. If there is no oil on the stick, add another quart or less if some oil is showing.
As the engine warms up, monitor the oil TEMPERATURE gauge (See Photo 3). As the engine comes up to normal operating temperature, the oil in the reservoir will expand and the oil LEVEL gauge will start to move.
As the temperature reaches the top of the low temp segment, add enough additional oil to get the level gauge to move to the top of the normal level. This is all done with the engine idling. Recheck the dipstick for normal oil level indication (engine at idle), and take a quick road test. Look for any leaks and check that the level gauge is at the top at idle and the temperature is in the normal range.
Water-cooled cars have a similar procedure for the oil change. Oil capacities are slightly reduced, but the dry sump oil system and coolant lines are still exposed and vulnerable, maybe even more so than on air-cooled cars.
Boxster models have some of the service points inside the rear luggage compartment (See Photo 4), and some under the engine cover (See Photo 5), which requires a procedure best followed by looking in the owner’s manual. The top must be partially lowered (See Photo 6).
Two tips here: the parking brake must be on to operate the top; and be careful with the vinyl rear window, especially in cooler weather (See Photo 7).
You may not easily see the drive belt on either model, but there is one, and the procedure to replace it is quite involved. Cooling system performance on these models is partially influenced by the oil system as well. Any instance of overheating or indicated high engine temperature should be immediately investigated. The rubber hoses throughout the car for oil and coolant are the most likely leak points, but water pump failures are not uncommon (See Photo 8).
On the air-cooled cars, the drive belt or belts are easy to see and determine their condition. Adjustment of the V-type belts is either by pulley spacing in the case of the A/C and P/S belts, and by shim adjustment of the alternator pulley. It’s very important to get the correct length and size (width) of belts to make the adjustments correct, as the amount of adjustment is very limited. There is a special wrench (spanner) to hold the alternator pulley for removal and installation of the retaining nut. The alternator belt adjustment is critical for two reasons — belt life and survival of the alternator bearings. A close look at the alternator-driven fan will make it obvious what a failure of the shaft bearings would cause. There is very little room for movement inside of the fan housing.
The water-cooled cars use a serpentine belt for accessory drive. Though the belt drive is very typical, due to space limitations and accessibility, belt replacement is a chore on either the Carrera or Boxster. The Boxster requires certain steps to be able to even see enough of the belt to make a judgment on condition.(See Photo 9)
2000 Carrera belt replacement procedure:
Remove the entire air cleaner and intake ducting.
Turn the tensioner with a 24 mm wrench, while removing the belt from the pulleys. Follow the routing diagram, or make a picture of the belt routing before removal.
Check the operation of all driven pulleys, and inspect for any debris in the pulley grooves, paying particular attention to the water pump and the force needed to turn it. Any resistance can indicate an imminent failure.
Install the new belt; reinstall the air filter and intake ducting.
Boxster belt replacement procedure:
Remove the passenger seat by disconnecting the electrical connector and removing the mounting bolts (torx).
Remove the service cover behind the rear wall carpet by removing the mounting bolts.
Using a 19 mm wrench, turn the tensioner while removing the belt from the pulleys.
As indicated above, inspect the pulleys and install the new belt following the routing diagram.
For either model, if there is any indication of binding in the water pump pulley, this would be the time to replace it. Replacement of the water pump on either of these models is a time-consuming process, but if the water pump is leaking or difficult to turn, it must be replaced to prevent further damage from overheating or loss of coolant.
On the Carrera, the water pump can be accessed only by removing most of the exhaust system and the rear engine support bracket (See Photos 10 and 10a). Start by draining the cooling system at the plug on the bottom of the thermostat housing. Put the car on a hoist and use an underhoist jack to support the engine. Remove the brackets for the catalytic converters and loosen the retaining bolts for the rear engine support carrier. The upper bolts just need to be loosened and, after removing the small locating bolt, the carrier can be rotated out far enough to access the water pump. Though the bolts are difficult to access, there is enough room to remove and replace the pump.
On the Boxster, you have a choice of doing the job through the service hatch inside the car, or from below, since you will be draining the cooling system anyway. Access is terrible either way, so be prepared for a workout in either case. Other than the access point, the replacement of the water pump is the same as on the Carrera.
After replacement of the water pump, or any cooling system service, it will be necessary to refill the system. This is best accomplished with a vacuum fill system. Trying to get the system full by any other method just does not work well. Remember that with water cooling comes numerous hoses, radiators and a heater core.
Other systems on these cars are standard high-performance components. Brake systems are all 4-wheel discs with multi-piston calipers on the higher performance cars and cross-drilled rotors from the factory on others. Though some repairs are more difficult due to space or access, the quality of materials makes most repairs routine, but time consuming. Only the best-quality parts that meet or exceed OEM specs should be used for repairs.
It’s important to remember when working on these cars that they’re capable of very high speeds, and some owners will press the limits at any opportunity. It’s imperative that all work performed on these cars be of the highest quality, and attention to detail must be part of any maintenance or repair. A full inspection should always be part of any service work, as a missed fault could be the cause of a serious accident.
The best part of any Porsche service or repair is the mandatory road test. Just be careful.