NEED HELP 5.3l Chevy trailblazer lt ext engine tick

Nordic76

Original poster
Member
May 28, 2019
2
Mcconnelsville Ohio
Hi guys I have a engine tick I’m assuming is coming from cylinder number 2 because when I unplug coil pack it stops, I have tried everything I could think to find it,it all started after I did a tune up for a misfire on number 6, initially I changed plugs and wire misfire went away but now I have a aggravating ticking noise I replaced the coil pack on #2 did nothing,engine flush did nothing,removed valve cover rocker arms and push rods look fine cleaned them and reinstalled them still didn’t work,is it possible that number 2 fuel injector could be causing this I have no check engine light on now so I’m stumped on this can’t understand why it happened after a tune up,any help would be great thanks.
 

Mike534x

Member
Apr 9, 2012
894
Hello! Welcome to the site!

Did you use AC Delco parts by chance? These trucks are VERY particular, and do not seem to play too kindly with anything that isn't OEM. Would you be able to provide a little more about the truck? like its maintenance history and mileage?

The 5.3 introduced in the 05 model year has valve cancelling lifters (usually referred to as DoD or AFM), that are prone to failure, and sometimes there is an audible ticking sound coming from the affected lifters. I used to have an 05 EXT that dropped the #4 lifter while on a road trip out of town, a few days/weeks prior it developed a "tick/tapping" sound before the incident, but I thought nothing of it until it happened. There's no harm in pulling the injector and giving it a cleaning (GM Upper Engine and Fuel Injector Cleaner is whats recommended) and see if it clears up.

If you could, perhaps record the video, and upload it to YouTube and post here for everyone to listen? My Envoy had a tick that developed a summer or too ago, but it happened to be 2 of the exhaust manifold bolts breaking from the passenger side of the engine causing an exhaust leak that sounded like I had a bad lifter.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
When does the ticking happen? Idle? At speed/cruising? If while cruising and DOD activating (4 cyl. mode), try disconnecting the vacuum sensor on the brake booster to disable DOD (engine light will eventually come on and throw a code for it). If the ticking goes away, it's a bad lifter.

However, cyl. 2 isn't one of the cylinders that deactivate with DOD. I would still disable DOD permanently as it is a very failure prone system.
 

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