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How can I tell whether an LS lifter is actually collapsed rather than just noisy?
A collapsed LS lifter usually gives you more than noise: a single-cylinder misfire (often with a cylinder-specific misfire code and check-engine light), rough idle and lost power. The valve on that cylinder isn't opening fully, and with the valve cover off there's often visible slack (a loose rocker) on that cylinder. A merely noisy lifter ticks but the cylinder still makes power.
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On AFM engines the deactivation lifters are the common failure. A lifter that doesn't "re-lock" leaves a dead cylinder even before you hear a tick. Left alone, it can wear the cam lobe, bend a pushrod or shed parts into the oil. A confirmed collapsed lifter means pulling the heads and replacing all 16 lifters (and the cam, if it's damaged or an AFM cam).
We recommend checking oil pressure before blaming a lifter, since a bad oil-pump O-ring or an exhaust leak can sound just like one. A healthy lifter should pump up within about five minutes of running, so one that's still noisy at full operating temperature is a real suspect. Right after shutdown, a pushrod that pushes down easily suggests that lifter has bled down, though that test isn't conclusive alone; cylinders 7 and 8 are the last to get oil and the first to drain, so check them first. With rocker bolts at 22 lb-ft and everything set correctly, a mild sewing-machine sound is normal for an LS.
Check this first:
- Verify oil pressure and inspect the oil-pump O-ring
- Rule out an exhaust leak
- Check pushrods on cylinders 7 and 8 right after shutdown
- Confirm rocker bolts are torqued to 22 lb-ft
Based on what we've seen work across our own builds, our friends' builds and the wider LS community, reviewed by our lead shop tuner (over 20 years of LS and LT tuning experience). Every combination is different, so use at your own risk and check our safe tuning limits before any wide-open pass.
Go deeper
Check this first
- Isolate the noisy cylinder with a stethoscope; check for collapsed lifter by pushing on rocker with valve closed
Try this, then this
- Verify rocker bolts at 22 ft-lb and pushrod length — loose rockers mimic lifter tick. Worked if: tick stops
- Replace lifters — collapsed lifter confirmed. Worked if: tick gone
How you know it's fixed
- Tick gone at all RPM after lifter replacement
Still not fixed?
- Check cam lobe wear and oil pressure to the lifter galley
Key numbers
| What | Value |
|---|---|
| Rocker arm bolt torque | 22 lb-ft (30 Nm) |
| Rocker torque corroborated | 30 Nm / 22 lb ft |
Every option we know of
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| Maker / product | Part # | Fits | Price | Where | Status / notes |
|---|---|---|---|---|---|
| GM LS7 lifters | 12499225 | all LS | about $150/set | Buy GM dealer | In production |
| Comp Cams short-travel hydraulic lifters | 850-16 | all LS | about $400 | Buy Summit | In production needs correct preload |
| Johnson 2110R drop-in lifters | 2110R | all LS | about $500 | Buy BTR | Small batch premium option |
Prices are approximate as of September 2026. We list every option we know of, including small shops and used parts we can't link to. Confirm fitment with the seller.
Time and cost: Heads-off lifter swap: 6-8 hours
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