Tech Tips: 1975-'89 Porsche 911 Turbo

By adding a turbocharger–along with bigger brakes and those healthy flares–to its classic 911, Porsche essentially put an FIA race car on the street with the 911 Turbo. For expert advice on these cars, we turned to Lou Verdiales, owner of Porsche shop Aero Dynamics. Lou also serves as the PCA’s official expert on all iterations of the 911 Turbo, including the GT2 model.

EXPERT:

Lou Verdiales
Aero Dynamics
(386) 304-0380
Port Orange, Florida

Proper maintenance dictates frequent oil and filter changes, checking and adjusting valves, and inspecting the Bosch K-Jetronic fuel injection for proper operation on early cars.

Most of the regular maintenance will have to be completed with the engine out of the car, as many components will be difficult to access. This typical engine-out service should occur every 3000 miles or 12 calendar months. Average time to drop the engine is about 3.5 hours, and mounting it back in the car typically consumes the same amount of time.

Components such as the ignition system, fluid and air hoses, and belts will have shorter service lives than their naturally aspirated siblings due to the extra heat in the engine compartment–up to 40 percent extra. Again, these maintenance items should be addressed during an engine compartment inspection every 12 months.

Exhaust smoke with no other symptoms calls for an inspection for the possibility of failed seals on the turbocharger. You can check by looking for oilin the intake tubing. Unfortunately, turbo failure is fairly common due to poor maintenance. Keep in mind that it’ll cost about $600 to $800 to have a turbocharger rebuilt. Luckily, removing the turbo- chargers does not require dropping the engine. After removing the rear bumper, you should haveample room to remove the unit.

Engine compartment perimeter seals must be in good condition. Bad seals can cause overheating in stop-and-go traffic by allowing hot air under the car to rise and then be reingested by the cooling fan and intake.

The wastegate should be inspected for proper operation to avoid overboost. These cars came from the factory with a fuel pressure safety switch set to activate if the engine experiences anything beyond 0.8 bar of boost. Unfortunately, many owners have bypassed this switch, so you may want to check if it’s operational. If you see readings greater than 0.8 bar on your boost gauge, inspect both the wastegate and fuel pressure safety switch.

When considering a 911 Turbo purchase, hire an experienced technician to conduct a thorough inspection, including a leak-down test and a head stud inspection. These steps should help you select the right car.

If you’re in the market for one of these cars, there are basically two avenues you can tread. If you want a more primal Porsche experience, an early car (1975-’79) may be more to your liking than a late car (1986-’89). And of the early cars, a ’78 or ’79 will have a larger-displacement engine, better brakes and an intercooler. However, the later cars may give you a slightly better bang for the buck. The improved HVAC and electrical systems make them more advanced, and on average they sell for about 10 or 15 percent less than the early cars.

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