Champion Parts FAQ: Spark Plugs, Resonators, Starter Motor Repair, and Head Gasket Mistakes

I've been an applications engineer at Champion Automotive Parts for seven years. The title sounds formal, but most of my time is spent answering questions—from OEM buyers and Tier 1 supplier engineers to home mechanics who got my number from a friend. In those seven years, I've chalked up roughly $15,000 in mistakes that were entirely my own fault. I kept a list so the rest of our team doesn't repeat them.

Here's the honest version of the questions I hear most:

• What's the real difference between Champion copper and iridium spark plugs?
• What's actually inside of a resonator?
• Starter motor repair: fix it or replace it?
• How to change a head gasket without paying for the job twice.
• What does total cost of ownership actually include?
• What do I ask before approving any component quote?

What's the actual difference between Champion copper and iridium spark plugs?

The Champion Copper Plus RN9YC spark plug has a copper-core center electrode. It's a workhorse part—great conductivity, dependable firing, and a price that's hard to beat. The RN9YC is a common replacement in Jeep 4.0 engines and a lot of Ford and GM pushrod engines. For conventional ignitions and typical 20,000–30,000 mile change intervals, it's the right call.

Champion iridium spark plugs use an iridium alloy tip on a thinner center electrode. Iridium's melting point is much higher, so the tip can stay small and concentrate the spark better. That's where you get improved firing efficiency and a 60,000+ mile service life. The tradeoff is price: $8–15 per plug instead of $3–5. Maybe $7–13 now, I'd have to check current pricing.

Here's the mistake I made: I recommended copper plugs to a fleet customer without asking about duty cycle. Their trucks ran around 100,000 miles a year. The copper plugs wore out every few months instead of yearly, and the labor cost on a 25-truck fleet erased the parts savings before the fourth month. Looking back, I should have done the total-cost math before I opened my mouth.

One more thing: don't cross heat ranges. A plug that runs too hot risks pre-ignition; one that runs too cold fouls. The engine spec is the right answer. If the manual says copper, use copper. If it says iridium, don't try to save $8 a plug—I've done that, and the rework cost me a lot more than $8.

What's actually inside of a resonator?

In most cases: a perforated pipe running through a sealed chamber. The chamber is tuned so sound waves cancel out specific exhaust frequencies—usually the ones that cause highway drone. Some resonators pack fiberglass or stainless steel mesh around the pipe; some are just empty chambers. Either way, it kinda looks like a simple metal box, but it's doing real acoustic work.

The "inside of a resonator" question usually comes from someone who wants to gut it. I get it—I wanted the same thing on my own truck. What changed my mind: a customer wanted to replace a resonator with a lightweight extrusion to save about 4 pounds. From a manufacturing standpoint, it was easy. From a noise standpoint, it failed. The drone at 3,200 RPM was unbearable, and the redesign scrapped the weight loss completely. That was a prototype and rework bill no weight saving justified.

I'm not an NVH specialist, so I can't speak to the acoustic math. What I can tell you from a manufacturing perspective is that the resonator is not a random metal box. If you remove it, budget for testing and tuning time.

Starter motor repair: fix it or replace it?

Diagnose first. I once replaced a perfectly functional starter on my truck because it clicked but wouldn't crank. The real problem was a corroded ground cable between the battery and the engine block. A $14 cable and 20 minutes of installation. I was $212 into a remanufactured starter and a lost Saturday before I figured that out. The most frustrating part: I knew how to do a voltage drop test. I skipped it because I wanted the repair to be over.

If the cranking is slow but steady, the battery and cables are still on the suspect list. If the starter spins but doesn't engage the flywheel, the drive gear is the problem, not the motor. Knowing which one you're seeing will save you from buying the wrong part.

If the starter is genuinely bad, the failure often lives in a replaceable component—solenoid contacts, plunger, or brushes. A contact and plunger kit is usually $20–40. A bench rebuild at an auto-electric shop runs about $90. A remanufactured unit is $150–250 plus core deposit. And check the starter relay and ignition switch before condemning anything; both mimic starter failure.

For an older vehicle you plan to keep, rebuilding wins on total cost. I can only speak to domestic vehicles, though—if you're working on an import where rebuild parts aren't on the shelf, replacement is the practical call.

How to change a head gasket without paying for the job twice

The service manual has the full procedure. I'll just cover where the money gets lost, because that's where I lost mine.

Step one: confirm the gasket is actually failing. A compression test and a leak-down test tell you whether combustion is leaking into the coolant, coolant into the cylinder, or neither. I've seen a head pulled for nothing because someone skipped the leak-down test.

Step two: measure the head for flatness before reinstalling anything. Mine was warped slightly past spec, and I skipped the straightedge check because it looked fine. The new gasket failed about 300 miles later. That error cost $890 in parts and machine shop time, a week of waiting, and a second full teardown. An $85 surface cut would have fixed it. Also send the head for a pressure test if the engine overheated badly—cracks like to hide.

Step three: torque the head bolts in the factory sequence, in the stages the manual specifies (usually two or three passes). Clean and lightly oil the threads, use a calibrated torque wrench, and don't extend the leeway the manual gives you.

If you have the tools, the manual, and the patience to measure instead of eyeball, a head gasket is doable. If you're missing any of those three, get a quote before you start. When a shop estimate tops half the vehicle's value, total cost thinking says a used engine—or a different vehicle—starts looking reasonable.

What does total cost of ownership actually include?

Unit price, tooling amortization, shipping, packaging, minimum order quantities, lead time, defect risk, rework, and the hours your engineer spends chasing documentation. Add the cost of a line stoppage if a batch arrives late or doesn't fit. That last one can wipe out years of parts savings in a single afternoon.

A real example from our shop: a stamped bracket at $2.10 vs. a competitor's $2.35. Same print, same material. On 50,000 pieces, the difference is $12,500. But the $2.10 supplier quoted a 6-week lead time against the other's 3 weeks. After carrying cost and the risk of a line stoppage, $2.35 was the cheaper part.

I'm not a cost accountant, so don't quote me on the exact formula. But the principle holds: add up every dollar a part costs before it becomes a part on the vehicle. And that's before counting your own time. Every revision, every email chasing a drawing, every trip to the supplier's facility for inspection is part of the real price.

What do I ask before approving any component quote?

This last one is for the buyers and engineers in the room. I've built a pre-order checklist from my own scrap heap, and it comes down to three questions.

1. What's the process capability on critical dimensions? A supplier can hit every number on day one and drift by day ten. Ask for Cpk values on special characteristics before you sign off on a PPAP.
2. What's the total cost, not the unit price? Tooling amortization, shipping, packaging minimums, revision fees. Add them all.
3. Who verifies quality, and with what evidence? In automotive, IATF 16949 requires statistical process control on special characteristics. Ask to see the data.

The $500 quote that becomes $800 after shipping, setup, and revision fees is not cheaper than the $650 all-inclusive quote.

My most expensive mistake: I approved a stamped part for a $3,200 order based on a perfect first article. The production run drifted out of control, and the components wouldn't assemble. $3,200 went to scrap, plus $890 in rework and a 1-week delay. I've seen that pattern more times than I'd like. When I say "more times," I do not mean two or three—I've documented twelve in the past four years.

If a supplier won't share process data, that's important information in itself. The phrase "don't worry, it's fine" has cost me more than any honest "we can't measure that" ever did.

I now calculate total cost of ownership for every part I source. It takes ten extra minutes, and it has saved me more than any price negotiation I've ever walked into.