This Cylinder Is Toast—And So Was This Customer's Patience
Published about 2 months ago • 6 min read
July 8th, 2025 — Issue #0003
This Cylinder Is Toast—And So Was This Customer's Patience
A Ticking Engine, A Dead Cylinder, And A Pin That Walked Away... When 210 PSI Doesn’t Always Mean All Is Well
Hi Reader,
Welcome to your weekly boost of inspiration from the shop floor. Torque Authority is not your average industry blog—it's a spark fired from the shop meant to reignite your drive, your grit, and your purpose.
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From the Driver's Seat—Featured Story
It all began with a tick—and not the kind you pull out with tweezers.
Cylinder 4 was deader than a parts order on a Friday afternoon. No spark, no fire, no signs of life.
Compression? Perfect—all cylinders reading 210 PSI. Fuel? Flowing. Ignition? Swapped, tested, and sworn at by the technician profusely.
And yet, the misfire in cylinder 4 laughed this technician square in the face.
To add insult to injury, the starter fuse began to blow intermittently when cranking as if the engine was saying, “Nope, I’m done for the day.”
Image Credit: Microsoft Copilot
This shop had already followed a bulletin pointing them towards replacing the exhaust camshaft roller followers. They had even consulted the sacred scrolls of the Technical Assistance Center.
Then I got involved. I travelled to this shop and confirmed the manual compression in cylinders 3 (known good) and 4 (bad) were both reading 210 PSI during a cranking compression test. The injectors, ignition coils, and plugs had already been swapped between cylinders, and yet I stared a cylinder 4 dead-miss in the face.
Something isn't adding up here, I thought to myself. Air, fuel, spark, and compression (at the right timing) are all a cylinder needs to fire.
Curious, I plugged in my Picoscope with the pressure transducer into Cylinder 3, captured a waveform, and then plugged it into Cylinder 4.
I didn't expect to find anything, I just wanted to get a good visual of what was taking place inside each cylinder.
Known Good Waveform (Cylinder 3)
This waveform showed what I had expected to see for a good cylinder. A pressure spike between the compression and power strokes, and a slight vacuum during the intake stroke—normal operating conditions for a 4-stroke engine.
But then I looked at the Cylinder 4 waveform.
And at first, I was very confused.
Cylinder 4 - Dead Misfire
It took me a while of staring at the waveform before I figured out what was going on.
I saw high spikes between the intake and exhaust strokes—no bueno.
The exhaust valve must not be opening, I realized. There's no other way a pressure spike like that can happen!
That's when it all started to add up. The "good" compression reading in Cylinder 4. The starter fuse which would blow intermittently. The ticking noise heard initially. All clues hiding the truth in plain sight.
The cranking compression reading in Cylinder 4 was deceptive—it looked good at first glance, but only because we technicians normally associate a fault only with LOW compression.
In this case, we had too much compression—and at the wrong time. Unfortunately, the cranking compression test (with a mechanical compression gauge) would never show this. And it would generate a lot of resistance for that starter motor.
But how could only one cylinder's exhaust valve not be opening?
It wasn't apparent what the root cause was until the camshaft was removed from the camshaft carrier assembly (part of the cylinder head).
Internally Splined Camshaft
Camshaft Pin Missing
The pin in the original exhaust camshaft had walked out, allowing the camshaft to separate at one end. With a new cylinder head and camshaft carrier assembly installed, the concern was resolved. Cylinder 4 is now happy, and the starter motor fuse is now staying cool. 😎
Here is what I learned from this case:
Not every test is as conclusive as we typically think they are—like the compression test in this case. Be careful not to discard possible causes because one perspective gained from a particular tool appears good.
Not every tool is perfectly suited for every job. Even something as trusty as a mechanical compression gauge can lead you astray for a while without an understanding of the bigger picture.
Don't forget the value of staying curious—and don't be afraid of using a tool like the Picoscope to run a test, even if you're not sure you'll find anything. In this case, I found it right away.
I hope you enjoyed the story! Please share this article with a friend if you did.
Don't forget we've created a free online Skool community where fellow troubleshooters, thinkers, and diagnostic detectives can swap stories, wisdom, and wiring diagrams. 'Torque Authority' isn't just a newsletter, it's the start of a movement. Come be a founding member by joining the party here:
Join Torque Authority Hub: Where Automotive Technicians Transform into Diagnostic Daredevils. Embrace your worth, master your craft, and drive towards financial autonomy with a community that gets it.
This week's Featured Story is brought to you by:
T. W. Mulder
Author | Writer | ASE Certified Master Technician | Field Service Engineer
Torque Spotlight
In this section each week we highlight a person—an innovator, subscriber, engineer, or even a business—who has made a positive impact in our industry. This is the place in Torque Authority where their authority in the Automotive Industry is highlighted.
This week's highlight is on Lucas Nicholson, Field Service Engineer at GM.
From turning wrenches at Tri State Tire to leading as General Manager, Lucas has built a career grounded in grit and growth. At Ford, he rose from Technical Support Analyst to Vehicle Off-Road Specialist and on to Field Service Engineer, and now serves as a Field Service Engineer at GM — where his deep technical insight keeps vehicles on the road and innovation in motion. Beyond the shop floor, he's a thoughtful voice in industry conversations on LinkedIn, always pushing the dialogue forward. His journey is a masterclass in hands-on leadership and relentless curiosity. For the years I have known him, it has been an honor to work with and around him.
Pit Stop Wisdom
One quote of wisdom for you to consider this week...
"Success is getting what you want. Happiness is wanting what you get."
- Dale Carnegie
Toolbox Tip
This is where we share one practical resource: a tool, app, book, strategy, or event which can have a positive impact in YOUR life.
This week's Toolbox Tip is on a strategy I have used to increase my focus: The Bullet Journal Method.
Did you know? Every year between 1950 and 2000, Americans increased their productivity about 1-4%. However, since 2005, this growth has slowed in advanced economies, with a productivity decrease recorded in the United States starting in 2016.
In a trade where precision and focus are everything, the Bullet Journal Method offers more than just a way to jot down to-dos—it’s a mindset shift. Developed by Ryder Carroll, this analog system encourages readers (and I'll add technicians) to slow down, reflect, and plan with intention. By stepping away from screens and embracing pen and paper, you’re training your brain to prioritize, troubleshoot, and stay present. Analog journaling reduces digital distractions and builds a stronger connection between your thoughts and your actions. Whether you're tracking diagnostic steps, logging customer concerns, or sketching out a wiring diagram, the Bullet Journal Method becomes a custom tool—just like your favorite 10mm socket. Intentionality isn’t fluff—it’s a skill. And like any tool in your box, it gets sharper the more you use it.
Your Turn Behind the Wheel
🔧 Question of the Week What’s the longest you’ve chased an issue before finally cracking the case? Bonus points if the leading test result was “perfect” when you first tested it. Let us know by responding to this email!
📸 Caption This Got a funny caption for the image of the grumpy V8 with a dead misfire in the story above? Hit reply and drop your best one-liner. Funniest entry gets bragging rights and a shoutout in the next issue!
✍️ Share Your StoryEver had a part fail in a way that made you question the laws of physics? I’m talking cam pins that vanish, fuses that blow for fun, or components that look fine but sabotage everything. Send us your strangest mechanical betrayals—We might feature your story in the next issue.
Ready to unlock the potential within you and become a more confident automotive diagnostician? Check out Hotwire Your Skills: The 10-Step Playbook to Six-Figure Success for Automotive Technicians
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