Another Trip to the Shop for Our Air-Cooled 911

The other day, my husband took our air-cooled 911 (964) in for preventive maintenance once again. Just like last time, he brought it to B-Force, a shop near our home. You can read about them here.

I couldn’t help asking, “Didn’t you take the air-cooled 911 in for service just a couple of months ago? What are you having done this time?”

“There’s no major problem or anything. I just want to stay on top of preventive maintenance so we can head out on really long grand-touring trips with complete peace of mind.
This time, I want to replace the distributor belt and fix an occasional noise from the rear blower fan.”

That made sense…

What Was Serviced on the Air-Cooled 911?

The work on the air-cooled 911 took about a week. When my husband went to pick it up, the list of jobs came to:

• Replace the distributor belt, rotor, and cap
• Replace the fan and motor inside the rear blower assembly
• Track down and eliminate a noise from the driver’s door
• Adjust the tension on the belts

“Wait, what exactly is a distributor? And what’s a blower motor? What difference does replacing them make?” I asked.

“A distributor—‘dizzy’ for short—is a device that sends electrical current to each cylinder at the right time to create the spark that ignites the fuel-air mixture. If the current isn’t delivered to each cylinder at the correct moment, the engine won’t run properly, so it’s an important component.
The 964 has twin-spark ignition, which means each cylinder has two spark plugs. That means the ignition system has to send current to all 12 plugs—two for each of the six cylinders—at exactly the right time.
So the 964 has two distributors, arranged one above the other. A small belt connects them and keeps their ignition timing in sync. If that belt wears out and breaks, the timing can go off, costing the engine power. In the worst case, the plugs could fire at the wrong time and, apparently, cause serious engine damage.”

Porsche 964 distributor

That was his explanation. I’m not especially familiar with the inner workings of a car, but I think I got the general idea. “So you replaced the belt because it looked like it was about to break?” I asked.

“No, it wasn’t about to break, and there wasn’t anything wrong with how it was running. But the service records show that the complete distributor was replaced in 2001, when the car had 25,000 km on it. It hadn’t been replaced in the 18 years and more than 40,000 km since then, so I wanted to replace it as a preventive measure.
Apparently, the belt itself wasn’t in especially bad shape. But the rotor, which distributes the electrical current, and the cap were showing wear, so the shop recommended replacing those, too. (Apparently, replacing the entire distributor would have been pretty expensive.)”

Porsche 964 distributor belt, rotor, and cap

I see. “And what does the blower fan do?” I asked.

“I’m not sure what its official name is, but it’s a fan that directs hot air from the engine to the heat exchangers to provide cabin heat. Lately, it’s occasionally been making a loud grinding noise. Apparently, it doesn’t affect how the car drives, but it was bothering me, so I had it replaced.
Replacing the entire assembly would apparently cost about ¥150,000 for the parts alone these days. This time, the shop kept the cost down by using aftermarket replacement parts for the motor and fan.”

Porsche 964 rear blower fan

The inspection and maintenance came to about ¥199,000, including parts and labor—a very reasonable price, apparently. After the work was done, my husband took the car out and said it felt even better than before:

“Maybe it’s because we replaced the distributor rotor and cap, but the engine’s throttle response and pull through the rev range feel noticeably better. And fuel economy has improved a lot. I haven’t measured it properly yet, but I’d say it could be around 10 percent better.
The old cap and rotor were pretty black and worn. With new ones in place, maybe the current can reach each cylinder with less resistance.
The car feels so smooth. The more I drive it, the better this air-cooled engine seems to get—and now it’s even smoother. It feels completely different from when I bought it.”

Lately, we’ve had a lot of posts about running costs and maintenance. But with a classic Porsche like the 964, regular, attentive maintenance really is essential to the ownership experience.

Man, cars are expensive!