ACDelco Motor Mounts, Starter Relays & Alternators: What a Parts Buyer Actually Recommends

If you're replacing engine parts, stick with ACDelco for motor mounts, starter relays, and camshaft plugs—especially on GM vehicles. For alternators, the brand matters less than the spec. And for the record, the head gasket sits between the engine block and the cylinder head, which is why a failed one can turn your oil into milkshake. I've been buying parts for a repair network for six years, and these conclusions are based on real invoices, not marketing brochures.

Let me give you a bit of context. I'm the office administrator and purchasing lead for a 12-person auto repair chain (three locations). I manage about $350,000 in annual parts purchases across 15 vendors. I report to both the operations director and the accountant, so I see both the technical and financial side of every purchase.

Here's the thing: ACDelco isn't perfect, and they're not always the best value. But for certain components, the cost of cheaping out far outweighs the savings. Let me walk through the parts I get asked about most.

ACDelco Motor Mounts: Spend Here, Or Pay Twice

From the outside, a motor mount looks like just a hunk of rubber and metal. People assume the cheapest option is fine because it holds two pieces together. The reality is that cheap mounts fail quickly, and installing one takes a couple of hours. We learned this the hard way with a 2019 Chevy Malibu (the 1.5L turbo). The aftermarket mount from a well-known brand had the right shape, but the rubber compound was too soft. Eight months later, the engine was slamming sideways on hard acceleration. Looking back, I should have ordered the ACDelco mount from the start. At the time, the $35 savings seemed worth trying. It wasn't—the second install cost more in labor than the part saved.

ACDelco motor mounts are pretty consistent in quality. They're often the same supplier that builds the original part, so fitment is exact. If your car has hydraulic mounts (the ones filled with fluid), go ACDelco. No aftermarket brand has matched their durability in our shop.

ACDelco Starter Relay: Don't Trust the Cheap Cube

The starter relay is a small cube in the under-hood fuse box that sends power to the starter solenoid. When it fails, the engine won't crank, but the lights still work (which, honestly, confuses a lot of people). We had a customer with a 2016 Equinox that cranks sometimes and other times just clicks. A 'bargain' relay from a local parts store fixed it for two weeks, then the problem returned. The relay was not rated for the constant current draw. We replaced it with an ACDelco relay (the one with the exact GM number) and it's been fine for 14 months now.

If you ask me, the starter relay is a case where ACDelco is a no-brainer. It's still only about $12–$18 (this was back in 2024, maybe a little more now). Cheap relays are $6. The difference is less than a pizza.

Camshaft Plug: The Leak You Didn't Know You Could Have

Camshaft plug (a.k.a. expansion plug) is a small metal or rubber plug at the rear end of the camshaft bore. It blocks oil from escaping the cylinder head. If it corrodes or pops out, you get a rear oil leak that's hard to diagnose because it drips down the bell housing and looks like a transmission leak. We had a truck come in with 80,000 miles and a mysterious oil spot. The camshaft plug was leaking. Replacing it while the engine is in the car is tricky; you basically need to drop the subframe or pull the engine. That's why when we do timing chain work, we always recommend changing the ACDelco camshaft plug at the same time. It's a $20 part that can save you a $900 repair later.

'High Quality Alternator' Doesn't Mean What You Think

People hear the phrase high quality alternator and assume it means more amps. In my experience, the real differentiator is the voltage regulator and bearings. A few years ago, we bought a rebuilt alternator from a budget supplier. It had a 160-amp label (higher than the stock unit), but the regulator was garbage. The battery light flickered at stoplights. We replaced it under warranty—twice. The second time, we put in an ACDelco remanufactured alternator, and the problem went away. The ACDelco part was 145 amps, which was the original spec. The 'high quality' branding on the budget part was exactly that: branding. Per FTC guidelines (ftc.gov), vague marketing claims like 'high quality' need substantiation—so look for the actual specs and test results, not just the label.

Bottom line: for alternators, match the amperage to your vehicle's original spec, and choose a brand that provides a clear data sheet. ACDelco does that; many aftermarket brands don't.

Where Is the Head Gasket Located?

If you're asking where the head gasket is located, here's the simplest answer: it sits between the engine block and the cylinder head. In an overhead-cam engine, the head gasket forms the seal between the block and the head(s). It prevents coolant and oil from leaking into the cylinders, and it keeps combustion gases from escaping. If it blows, you'll often see white smoke from the exhaust, bubbles in the radiator, or milky oil (coolant mixing with oil).

Replacing a head gasket is not a beginner DIY job (we usually quote 12–16 hours of labor depending on the engine). ACDelco's head gasket is a good part, but honestly, the quality of the gasket matters less than the surface prep and torque sequence. If your engine needs one, buy a decent gasket, but invest the money in finding a technician who knows what they're doing.

How I Buy ACDelco Parts (and What It Costs)

When I order ACDelco parts, I usually go through a local distribution center for warranty simplicity. For small items like relays and plugs, USPS First-Class Package is still the most economical way to ship (see usps.com for current rates). It's not expedited, but for parts that aren't holding up a job, it's fine. Also, I always verify the part number on the box before pulling it out. Counterfeit ACDelco parts exist, and we once received a fake relay that looked almost identical but had a lower internal rating. Authorized distributors don't always prevent that, but they give you a warranty claim if it happens.

When I Skip ACDelco (Honestly)

To be fair, ACDelco isn't always the best choice. For non-critical parts like trim clips, wiper blades, or rubber hoses, aftermarket parts are fine. Also, for older cars that are no longer supported, ACDelco may not even make a part. And if you drive a Hyundai or Toyota, ACDelco's lineup is limited—stick with the original OE supplier for those cars.

I also understand why small shops and DIYers pick cheaper parts—you've got a budget and you want to get the job done today. I get it. But the math changes once you factor in labor. A $15 saving on a mount can turn into $150 if you have to install it twice. That's not a lecture, that's just the invoice reality.

One more thing: as a smaller buyer, we've never had ACDelco discriminate against our order size. We place $50 orders all the time, and they still answer the phone. That alone makes them worth keeping on the vendor list. Small doesn't mean unimportant—it means potential.

So, if you're doing a repair and the part is something safety-related or engine-critical, I'd put ACDelco at the top of the list. Just double-check the specifications, and remember where that head gasket lives before you start turning wrenches.