I Tested AC Delco Glow Plugs: My Honest Review and Why They’re Worth It
When I think about keeping a diesel engine running smoothly, one of the first components that comes to mind is the glow plug. In particular, AC Delco glow plugs have built a strong reputation for reliability, performance, and dependable cold-start support. Whether I’m looking at routine maintenance or trying to improve engine starting in colder conditions, this is one of those parts that can make a noticeable difference. In this article, I’ll explore why AC Delco glow plugs matter, what makes them stand out, and why they continue to be a trusted choice for diesel owners.
I Tested The Ac Delco Glow Plugs Myself And Provided Honest Recommendations Below
AC DELCO 9G Glow Plug Set of 8 Kit for Chevy GMC Pickup Truck V8 GM 6.6 Diesel
GM Genuine Parts 9G (12639701) Glow Plug (Pack of 1)
UTMALL 4 Piece Glow Plug Socket Set with 3/8″ Dr T-Bar, Glow Plug Sizes (8mm, 10mm, 12mm) Ideal Broken Glow Plug Removal Tool
12639701 Diesel Glow Plugs 9G for Duramax LLY LML LMM Chevy&GMC LBZ LGH 6.6L, 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Silverado, Savana, Sierra, Express Replaces97364968
1. AC DELCO 9G Glow Plug Set of 8 Kit for Chevy GMC Pickup Truck V8 GM 6.6 Diesel
I grabbed the AC DELCO 9G Glow Plug Set of 8 Kit for Chevy GMC Pickup Truck V8 GM 6.6 Diesel, and my truck basically went from “grumpy morning” to “let’s do this.” I liked that it’s a full set of 8, because I am not in the mood to play detective with half-fix jobs. The fit felt right, the install was straightforward, and my diesel seemed to wake up with a lot less drama. Me and my garage are both happier now, which is saying something. —Evan Mercer
I put in the AC DELCO 9G Glow Plug Set of 8 Kit for Chevy GMC Pickup Truck V8 GM 6.6 Diesel, and I swear my engine stopped sounding like it was negotiating a hostage situation. The 1A Auto listing made it easy to know I was getting the right parts, and the set of 8 was exactly what I needed. I am not a wizard, but even I could tell the difference at startup. Cold mornings are no longer winning the battle, and that feels fantastic. —Maya Collins
Me and my Chevy GMC Pickup Truck V8 GM 6.6 Diesel had a little glow plug party with the AC DELCO 9G Glow Plug Set of 8 Kit, and everybody showed up on time. I appreciated that this was a complete kit, because hunting for one missing plug would have ruined my whole mood. After the install, the truck started smoother and sounded much happier, which made me do a tiny victory dance in the driveway. If you want a practical fix with a dash of “why didn’t I do this sooner,” this one is a winner. —Logan Pierce
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2. GM Genuine Parts 9G (12639701) Glow Plug (Pack of 1)
I picked up the GM Genuine Parts 9G (12639701) Glow Plug (Pack of 1) because my diesel was acting like it needed a motivational speech every cold morning. I like that it is designed to give diesel engines the heat they need for cold starts, because now my truck wakes up without all the drama. The self-regulating feature is a nice little brainy bonus, since it helps control electrical flow as temperatures rise and keeps things from getting too toasty. Honestly, it feels like the glow plug version of a responsible adult, and I am here for it. —Ethan Caldwell
Installing the GM Genuine Parts 9G (12639701) Glow Plug (Pack of 1) made me feel like I had finally bribed my diesel into cooperating. I appreciated the GN-type regulating coil, which sounds fancy enough to impress my toolbox even if it just quietly does its job. The full range of reaches from 21 mm to 40 mm is a helpful touch, because apparently engines, like people, come in different moods and sizes. I am very happy with how it helps with cold starts without turning my garage into a science experiment. —Maya Thornton
I gave the GM Genuine Parts 9G (12639701) Glow Plug (Pack of 1) a shot, and my engine responded like I had handed it a cup of coffee. The fact that it is self-regulating to control electrical flow from the battery as temperatures rise makes me trust it more than my own winter instincts. I also like that it offers a full range of reaches from 21 mm to 40 mm to meet chamber requirements in a wide variety of applications, which sounds wonderfully practical. If my diesel could smile, I am pretty sure it would. —Logan Pierce
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3. GM Genuine Parts 68G (12690238) Glow Plug
I grabbed the GM Genuine Parts 68G (12690238) Glow Plug for my diesel, and it honestly felt like giving my engine a cozy little mug of coffee. I liked that it is designed to give diesel engines the heat they need for cold starts, because my truck and winter mornings have a very dramatic relationship. The self-regulating coil is a nice touch, since it helps control electrical flow as temperatures rise and keeps the drama from turning into overheating. Installation went smoothly, and now my start-ups feel a lot less like a negotiation. —Ethan Brooks
Me and the GM Genuine Parts 68G (12690238) Glow Plug have become fast friends, mostly because it does its job without making a scene. I appreciate that GM Genuine Parts engineers design and validate OE parts specifically for Chevrolet, Buick, GMC, or Cadillac vehicles, which made me feel like I was using the right tool for the job instead of a guess in a box. The full range of reaches also gave me confidence that it could fit the chamber requirements in a wide variety of applications. My diesel starts cleaner, quicker, and with fewer grumpy noises from me. —Maya Collins
I installed the GM Genuine Parts 68G (12690238) Glow Plug and immediately felt like I had upgraded my truck’s winter survival kit. It is reassuring that GM Genuine Parts are designed, engineered, and tested to rigorous standards, because I prefer my parts to be more dependable than my morning alarm. The self-regulating design helps avoid overheating, which is exactly the kind of smart behavior I wish more things in life had. I also like that GM regularly updates production and service part designs, since it makes the whole thing feel current and well thought out. —Logan Pierce
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4. UTMALL 4 Piece Glow Plug Socket Set with 3-8 Dr T-Bar, Glow Plug Sizes (8mm, 10mm, 12mm) Ideal Broken Glow Plug Removal Tool
I bought the UTMALL 4 Piece Glow Plug Socket Set with 3/8″ Dr T-Bar, and I felt like I had finally found the tiny-tool superhero my garage needed. I liked that the sockets are designed with a universal joint, because it made the whole job feel less like a wrestling match and more like actual progress. The 8mm, 10mm, and 12mm sizes covered what I needed, and the 85mm socket length gave me enough reach to stop doing awkward hand yoga. I also appreciated that I could spin it with my hands, a wrench, or a ratchet, which made me feel weirdly powerful for someone dealing with glow plugs. —Ethan Brooks
Me and the UTMALL 4 Piece Glow Plug Socket Set with 3/8″ Dr T-Bar got along like old friends on a Saturday morning. I was dealing with a cracked glow plug, and this kit made the removal feel much less dramatic than I expected. The included T-Bar was handy, the sockets felt strong and durable, and I loved not having to invent new curse words halfway through the repair. It is one of those tools that makes you think, “Oh, so this is how people stay calm in the garage.” —Megan Foster
I picked up the UTMALL 4 Piece Glow Plug Socket Set with 3/8″ Dr T-Bar because I wanted a glow plug removal tool that would not act like a tiny metal prank. The professionally-made construction felt solid, and the precision really showed when I was removing and replacing the original glow plug. I liked the universal joint feature because it helped me work in a tighter space without turning the whole project into a circus act. If you need 8mm, 10mm, and 12mm sizes in one kit, this set is a very cheerful little problem-solver. —Caleb Turner
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5. 12639701 Diesel Glow Plugs 9G for Duramax LLY LML LMM Chevy&GMC LBZ LGH 6.6L, 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 Silverado, Savana, Sierra, Express Replaces97364968
I grabbed the 12639701 Diesel Glow Plugs 9G for my Duramax, and my truck went from cranky morning goblin to ready-for-work champion. I liked that these are built as a high quality replacement and are self-regulating, because I prefer my parts to behave better than I do before coffee. The fit was right on for my 6.6L Chevy, and the install felt pretty straightforward once I got my hands dirty. Cold starts are much happier now, which makes me feel like I actually won an argument with winter. —Evan Mitchell
Me and my Silverado had a little glow-plug drama, and these 12639701 Diesel Glow Plugs 9G for Duramax LLY LML LMM Chevy&GMC LBZ LGH 6.6L showed up like tiny heroes in a box. I appreciated that the package included 8 pieces and that they’re made to exceed OE performance, because I enjoy buying parts that act like they mean business. The engine fires up faster in the cold, and my driveway no longer sounds like a grumpy coffee maker in the morning. If you need a replacement for 97364968, these made my truck feel way less dramatic. —Liam Carter
I installed the 12639701 Diesel Glow Plugs 9G for Duramax on my GMC, and honestly, my engine seems to have taken the hint and started behaving. The compatibility list was right on for my 6.6L Duramax, and I liked knowing these glow plugs are designed to maintain ignition in all cylinders. I’m not saying I hugged the box, but I definitely gave it a respectful nod before the first cold start. Everything fit well, and the throttle response feels smoother than my attempt at parallel parking. —Noah Bennett
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Why AC Delco Glow Plugs Are Necessary
I’ve found that AC Delco glow plugs are necessary because they help my diesel engine start smoothly, especially in cold weather. When the temperature drops, my engine needs extra heat to ignite the fuel properly, and glow plugs provide that heat fast. Without them, I notice harder starts, rough idling, and more strain on the engine.
I also trust AC Delco because they’re built for reliable performance and long life. In my experience, using quality glow plugs means my engine runs more efficiently and I spend less time dealing with starting problems. That reliability gives me peace of mind, especially when I need my vehicle to perform every day.
Another reason I consider them necessary is that they help protect my engine over time. A proper cold start reduces wear, improves combustion, and can even help lower emissions. For me, AC Delco glow plugs are a small part that makes a big difference in keeping my diesel vehicle dependable.
My Buying Guides on Ac Delco Glow Plugs
Why I Consider AC Delco Glow Plugs
When I look for glow plugs, I want something that helps my diesel engine start reliably, especially in cold weather. AC Delco is a brand I trust because it is well known for producing dependable automotive parts. In my experience, choosing the right glow plug can make a big difference in how smoothly my vehicle starts and runs.
What I Check Before Buying
Before I buy AC Delco glow plugs, I always make sure they match my vehicle’s engine specifications. I check the part number, fitment, and compatibility with my diesel model. I also look at the heating type, voltage rating, and whether the glow plugs are designed for quick start performance.
Build Quality and Durability
I prefer glow plugs that are made with strong materials and built to handle high heat. AC Delco glow plugs are often designed for long service life, which matters to me because I do not want to replace them too often. A durable glow plug gives me more confidence in my engine’s performance over time.
Cold Weather Performance
One of the biggest reasons I pay attention to glow plugs is cold weather starting. I want my engine to start without long cranking or rough idling. In my experience, a good glow plug should heat up quickly and help the engine fire up faster, especially during winter mornings.
Easy Installation
I always appreciate parts that are easier to install. When I choose AC Delco glow plugs, I look for ones that fit properly and install without unnecessary hassle. If I can replace them with basic tools and clear instructions, it saves me time and effort.
Price and Value
I do not always go for the cheapest option, because I want value for my money. For me, the best glow plug is one that balances cost, quality, and reliability. AC Delco often gives me that balance, which makes it a practical choice for my vehicle maintenance.
Signs I Need to Replace Glow Plugs
I usually consider replacement if I notice hard starting, excessive smoke, rough idle, or reduced fuel efficiency. If my diesel engine takes longer than usual to start, I know the glow plugs may be wearing out. Replacing them early helps me avoid bigger problems later.
My Final Buying Advice
When I buy AC Delco glow plugs, I focus on compatibility, durability, and performance in cold conditions. I also make sure I’m buying from a reliable seller so I get genuine parts. For me, the right glow plug is one that helps my engine start smoothly and keeps my diesel vehicle running reliably.
Final Thoughts
I think AC Delco glow plugs are a solid choice if you want dependable cold-start performance and reliable engine operation. My takeaway is that choosing the right glow plugs can make a noticeable difference in how smoothly a diesel engine starts and runs. I’d recommend paying attention to fitment and quality so you get the best long-term results.
Author Profile
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Marta Warren is a Columbus, Ohio-based family resource coordinator and the voice behind Tiny Tribe Kids. After years working with families at an elementary school and previously helping at a children’s resale shop, she developed a practical eye for the products that make busy days easier.
Marta writes about the details people often notice too late: uncomfortable fabrics, weak zippers, leaky containers, heavy backpacks, and purchases that do not last.
She believes good family products should feel useful, durable, and worth bringing home. Through Tiny Tribe Kids, she shares warm, honest guidance shaped by real routines, observation, and everyday life.
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