Why is my GMC Sierra 5.3 ticking from AFM lifters?

Short answer: Sierra 5.3 AFM lifters can tick and then collapse. Catch the tick early, confirm with a scan, and plan lifters—and often a cam—before a bigger failure.

Symptom: Tick on cold start, misfire, rough running, or a shop saying AFM lifters failed on a 5.3 Sierra.

What to check first

1. Record the tick when cold vs hot.
2. Scan for misfire codes on AFM cylinders.
3. Ask about TSBs and warranty special coverage for your VIN.
4. Use the correct oil viscosity—AFM is oil-sensitive.

Likely causes

1. AFM lifter collapse. Active Fuel Management lifters on 5.3 Sierras can collapse, causing a tick and misfires.
2. Camshaft wear following lifter failure. Failed lifters often chew the cam—repairs may include cam and lifters together.
3. AFM delete / DOD disabler choices. Some owners delete AFM after a repair to reduce repeat risk; discuss legality/emissions with your shop.

What it usually costs

Lifter/cam jobs are major. Warranty special coverage, if open for your VIN, is critical.

Is it safe to keep driving?

A light tick can be driven briefly to the shop; a loud tick with misfire should limit driving.

DIY or shop?

Shop job.

Recalls, bulletins and complaints in plain words

• Related recalls: NHTSA lists these recalls touching this area of the GMC: 14V007000 (2015-2015 model years, engine and engine cooling:exhaust system); 16V084000 (2016-2016 model years, electrical system:software). Check your VIN at nhtsa.gov/recalls. If your car is part of a recall, the dealer fixes it for free.
• Plain words: The complaint count below shows how often owners reported problems that mention these words to NHTSA. A count is not proof of a defect.
• NHTSA complaints: 0 keyword-matched complaints for GMC Sierra 2014–2019 (of 0 unique complaints queried, NHTSA complaints API by model year, queried 2026-11-06; keywords: lifter, tick, afm, misfire, cam) (NHTSA returned no data for 9 model-year queries). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In Gmc 2019 lifter failure!! on Reddit r/gmcsierra, an owner reported a 2019 lifter failure.
• In AFM DELETE on Reddit r/gmcsierra, owners discussed deleting AFM after lifter problems.
• In V8 and Duramax issues on Reddit r/gmcsierra, owners contrasted gas V8 AFM problems with Duramax concerns.

Quick tip

If your 5.3 Sierra ticks like a diesel on startup, assume AFM lifters until proven otherwise.

Vehicle focus: GMC Sierra 5.3 with AFM roughly 2014-2019 (similar Silverado pattern).

Safety / mechanic note

A collapsed lifter can damage the cam and leave you with a dead cylinder. Verify with a mechanic.