#2650: Non Impediti Ratione Cogitationis
About this episode
A rare 1986 Nissan Stanza wagon 4x4 becomes the focus, especially an ignition problem that clears after replacing the distributor cap and rotor—then returns every 5,000 to 6,000 miles. The hosts explain how a failing electrical path in the distributor/coil setup can cause rough running. The conversation then shifts to windshield issues: sun glare that looks like glitter, and why modern glass can pit quickly. Later, a steering-wheel jerk and a “sticky shifter” lead into diagnostic tips and a few offbeat NPR detours.
See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.
NPR Privacy Policy
1986 Nissan Stanza wagon 4x4
"What's up, Sam? [252.7s] I have a 1986 Nissan Stanza wagon 4x4. [259.1s] Jeez, that's a rare vehicle."
This is a 1986 Nissan Stanza wagon, and the “4x4” means it sends power to all four wheels. That usually helps it grip better on snow, dirt, or wet roads than a normal two-wheel-drive version.
The Nissan Stanza is a mid-size sedan/wagon from Nissan’s 1980s lineup, and this one is specifically a wagon with 4x4 (four-wheel drive). The 4x4 drivetrain is the key enthusiast detail here because it changes how the car handles traction on loose or slippery surfaces compared with a regular two-wheel-drive Stanza.
rotor and the cap
"Replacing the rotor and the cap, it'll run like a clock. For 5,000 or 6,000 miles."
On some cars, the spark plugs are fed by an ignition “distributor.” The cap and rotor are small parts inside that system that help send the spark to the right cylinder. If they wear out, the engine can start running rough or even shut off, and replacing them can make it run normally again for a while.
The distributor rotor and cap are ignition-system parts used on many older engines. They route high-voltage current from the ignition coil to the correct spark plug; if the cap or rotor wears, misfires and rough running can happen. Replacing them can temporarily restore proper spark timing and distribution.
ignition coils
"This car has two ignition coils. [345.7s] Yes. And it has along the top of the cap where one of the coil wires connects."
Ignition coils are what generate the strong electrical spark your engine needs to burn fuel. If one coil or its connection isn’t working right, the engine can stumble or run rough. The speaker is pointing to a problem affecting the second coil’s path.
Ignition coils are the components that convert the car’s low-voltage electrical power into the high voltage needed to create a spark at the spark plugs. When coil-related wiring or connections degrade, the engine can misfire or run unevenly. Here, the speaker notes the car has two ignition coils and ties a failing connection path to the rough running.
breaking down
"And I bet that's breaking down. [363.1s] Okay. Are you buying the caps from Nissan? ... That conduit for the second coil ... is breaking down and that's why the thing starts to run raggy."
“Breaking down” here means the electrical part is wearing out or failing internally. When that happens, electricity doesn’t travel properly, so the spark can be weak or inconsistent. That’s what can make the engine run rough.
In this context, “breaking down” refers to insulation or internal electrical components degrading over time—often from heat, moisture, or electrical stress. That degradation increases resistance or interrupts the high-voltage path, leading to weak or intermittent spark delivery. The host specifically suspects the long electrical conduit/path for the second coil is breaking down.
distributor caps
"Okay. Are you buying the caps from Nissan? [366.0s] No. Just, you know, regular parts. ... Don't forget that pretty soon, there's going to be a price turnaround on these distributor caps."
A distributor cap is part of the ignition system that sends electricity to the spark plugs. If it cracks or wears out, the car may start running rough because the spark isn’t getting delivered reliably. That’s why replacing it can fix the problem.
A distributor cap is the plastic housing on an older ignition system that routes high-voltage electricity from the ignition coil to the correct spark plug. If the cap or its internal contacts/connections break down, the spark can become weak or intermittent, causing rough running or misfires. In this segment, the host suspects the distributor cap/connections for the second coil are failing.
run raggy
"That conduit for the second coil, the one that has to travel the farthest or farther, [383.4s] is breaking down and that's why the thing starts to run raggy. [386.5s] Okay."
“Run raggy” means the engine is running unevenly, like it’s missing or stumbling. That often happens when the spark isn’t consistent. In this case, the host thinks the ignition-related parts are failing.
“Run raggy” is a colloquial way to describe rough, uneven engine operation—typically from misfires or inconsistent ignition. When the ignition system can’t deliver a consistent spark to the cylinders, the engine may shake, stumble, or idle poorly. The speaker connects this symptom to a failing electrical path in the distributor cap/coil wiring.
tread separation
"Well, it's possible there's a defect in the tire that you can't notice. There's a condition called tread separation where the actual tread will become separated from the ply below it."
Tread separation means the rubber “grip” part of the tire starts coming loose from the inside layers. You often can’t see it just by looking at the tire. If it’s happening, the tire can feel weird or vibrate and it’s safer to replace it.
Tread separation is a tire failure where the tread (the outer rubber pattern) starts to peel away from the tire’s internal layers (the ply). It can be hidden from view until it worsens, and it may cause vibration, noise, or handling changes. Because it’s dangerous, it’s a common reason to replace a suspect tire.
ply
"There's a condition called tread separation where the actual tread will become separated from the ply below it. Inside the tire where you can't see it."
A ply is an internal reinforcing layer inside the tire. It helps the tire stay strong and shaped. If the tread separates, it’s often separating from these internal layers, not just from the surface.
A ply is one of the reinforcing fabric layers inside a tire that helps it hold its shape and transmit forces. When tread separation happens, the tread can detach from these internal plies. Understanding “ply” helps explain why the failure can’t be seen from the outside.
rotate them
"Or better still to do one at a time. Rotate them somehow. So jack up one side of the vehicle and exchange the left front and the left rear."
Tire rotation means swapping tires to different wheel positions. It helps tires wear more evenly. Here, they’re also using it like a test—if the problem moves with the tire, the tire is probably the culprit.
Tire rotation is the practice of moving tires from one position on the vehicle to another (front-to-rear or side-to-side) to even out wear patterns. In this discussion, rotation is used as a diagnostic step: if the vibration follows the tire, the tire is likely the cause. If it stays, the issue is more likely suspension or steering-related.
ball joints
"But I'm just worried you might have something else wrong because whenever you have a vibration of any kind in the steering wheel, you should always suspect the suspension. Yes, right, right, right, right. You really should have someone take a look at the ball joints, the tie rod ends and all that stuff that's holding the wheels together."
Ball joints are parts that connect parts of the suspension and let the wheels move properly. If they wear out, the steering can feel off and you may get vibrations. They’re one of the first things to check when the steering wheel shakes.
Ball joints are suspension components that allow controlled movement between the steering knuckle and the suspension arms. If they wear out, they can cause looseness, uneven tire wear, and vibrations or steering feel issues. That’s why the hosts suggest inspecting them when there’s vibration in the steering wheel.
tie rod ends
"Yes, right, right, right, right. You really should have someone take a look at the ball joints, the tie rod ends and all that stuff that's holding the wheels together."
Tie rod ends are small joints that help connect the steering to the front wheels. If they wear out, the steering can feel loose or shaky. That can show up as vibration in the steering wheel.
Tie rod ends are steering linkage joints that connect the steering system to the steering knuckles. Worn tie rod ends can create play in the steering, leading to vibration, wandering, or imprecise steering response. They’re specifically called out here because steering-wheel vibration can come from worn steering/suspension joints.
catalytic converter heat shield
"I think the shift linkage is getting overheated due to the absence of the catalytic converter heat shield which fell off at about 35,000 miles."
The catalytic converter heat shield is a protective metal cover near the exhaust. It helps keep other parts from getting too hot; if it’s missing, nearby components can overheat.
A catalytic converter heat shield is a thin metal cover mounted near the catalytic converter to protect nearby components from exhaust heat. If the heat shield falls off, surrounding parts can run hotter than intended, which can lead to heat-related issues like stiff shifting.
shift linkage
"I think the shift linkage is getting overheated due to the absence of the catalytic converter heat shield which fell off at about 35,000 miles."
Shift linkage is the set of parts that physically connect your gear shifter to the transmission. If those parts get overheated, they can expand and become harder to move, so shifting feels stiff.
Shift linkage is the mechanical connection (rods/cables and joints) that transfers your gear-shift movement to the transmission. If it gets too hot, parts can expand and friction can increase, making the shifter feel stiff or harder to move.
low fluid
"I considered the theory of the low fluid, but I dismissed it."
Low fluid means there isn’t enough fluid in the transmission system. That can make shifting feel wrong because parts don’t get properly lubricated, but here the speaker thinks it wasn’t the real problem.
Low fluid usually refers to insufficient transmission fluid (or sometimes another related fluid) in a gearbox system. Low fluid can cause poor lubrication and shifting behavior, but in this discussion the speaker dismisses it as the cause.
Volkswagen Jetta
"Okay. What kind of a car is it? It's a VW Jetta, 1992."
This is a Volkswagen Jetta from 1992. It’s an older compact sedan, and people often choose it because it’s straightforward to work on and parts are usually available.
A Volkswagen Jetta is a compact sedan known for being widely produced and easy to find parts for. The 1992 model year is part of the early-1990s Jetta generation, which many owners recognize for its simple, serviceable mechanical layout compared with newer cars.
timing belt tensioner
"See, I was convinced [2027.9s] that it was your timing belt tensioner. [2031.8s] Because when these tensioners go bad [2033.6s] this is exactly the noise [2035.8s] that they make."
The timing belt tensioner is a part that keeps the timing belt tight. The timing belt has to stay properly tight so the engine’s moving parts stay in sync. If the tensioner goes bad, it can make a noticeable rattling or squeaking noise.
A timing belt tensioner is the component that keeps an engine’s timing belt at the correct tension so the camshaft and crankshaft stay synchronized. If the tensioner wears out or fails, it can create a characteristic noise (often a rattle or squeal) that changes with engine load or clutch use. In this segment, the speaker is suggesting that the noise pattern matches a failing tensioner.
clutch
"when you step on the clutch [2048.7s] is the bearing on the front shaft [2052.2s] of the transmission. [2053.9s] But if you're sitting,"
Here, the clutch pedal is used like a test switch. If the noise happens only when you press the clutch, it can point to parts connected to the clutch system.
In this context, the clutch is being used as a diagnostic clue: the noise changes when the driver steps on the clutch pedal. That suggests the noise may be related to components that move or unload when the clutch is engaged/disengaged.
bearing on the front shaft
"when you step on the clutch [2048.7s] is the bearing on the front shaft [2052.2s] of the transmission. [2053.9s] But if you're sitting,"
This is a small rotating part that supports a spinning shaft. If it wears out, it can make a noise that changes depending on how the drivetrain is being used.
A bearing on the front shaft refers to a rotating support component near the transmission’s input area. Worn bearings can create noises that vary with clutch engagement and vehicle load.
transmission
"[2048.7s] is the bearing on the front shaft [2052.2s] of the transmission. [2053.9s] But if you're sitting,"
The transmission is the part that sends power from the engine to the wheels, using different gear ratios. Here it’s mentioned because the noise might come from something inside it.
The transmission is the drivetrain component that transfers engine power to the wheels through gear ratios. In this segment, it’s mentioned because the suspected bearing is located on a shaft associated with the transmission.
Request an Explanation
Heard something you'd like explained? We'll add it to this episode.
Sign in to request explanations for terms you heard.
Want to learn more?
Browse our glossary for plain-English explanations of automotive terms, jargon, and concepts.
Help improve this episode
See something that's not quite right? Our annotations are AI-generated and can sometimes miss the mark. Click the flag icon on any annotation to suggest a correction.