Problems regarding Chevy 5.3L engines
Problems regarding Chevy 5.3L engines, AERA technical committee offers the following information. Regarding a ticking noise or misfire on 2005-2014 GM V8 engines. Therefore with AFM (Active Fuel Management, formerly known as displacement on demand (DoD)).
Engine ticking or misfires seem to be happening on cylinders 1, 4, 6 and or 7 on the effected engines.
Causing this ticking or misfire condition may be the result of an AFM lifter. This unlocks as soon as the engine is started or one that is mechanically collapsed /stuck all of the time.
If an AFM lifter unlocks as soon as the engine is started, low compression will be found on that cylinder during an AFM compression test. Along with the SES light, DTC PO300 and engine misfires on the related cylinders, but it is unlikely that any noise will be experienced.
If an AFM lifter is mechanically collapsed/stuck, low compression will be found on that cylinder during an AFM compression test. Along with a consistent valve train tick noise, SES light, DTC PO300 and engine misfires on the related cylinders.
These lifter concerns may be the result of internal locking pin damage, which may occur if the response time of an AFM lifter unlocking event is:
- Decreased due to low oil pressure
Internal engine sludge
VLOM (Valve Lifter Oil Manifold) wear
Plastic lifter guide wear
Lifter bore wear
Cam lobe wear
GM offers the following diagnostic steps in determining if this is the problem.
1. Perform a Cylinder Deactivation (Active Fuel Management) System Compression Test. If Problems regarding Chevy 5.3L engines, if the running compression of the misfiring cylinders stays below 25 PSI. Regardless of the AFM solenoid being commanded on or off. And AFM lifter is mechanically collapsed/stuck or unlocking as soon as the engine is started.
2.Perform a Cylinder Deactivation (Active Fuel Management) Valve Lifter Oil Manifold Diagnosis and Testing. If the test is procedure #1 isolated a possible AFM Lifter concern, it will lead to this test, which test the VLOM for proper operation. When Problems regarding Chevy 5.3L engines, GM states a limited amount of air will leak from the bleed holes and outlets ports. Even when the solenoids are off, compare the amount of leakage to verify all 4 solenoids are operating the same. If it isolates a concern with the VLOM, replace it and reevaluate the concern.
3. The AFM lifters can also be monitored for proper operation by carefully inspecting the cylinder. Numbers 1, 4, 6 & 7 rockers and valves while cranking or briefly and safely running the engine with the valve covers removed. Therefore Problems regarding Chevy 5.3L engines, if the valve(s) of an AFM cylinder stop moving while doing this test, the AFM lifter is causing the concern.
Problems regarding Chevy 5.3L engines, carefully inspect the camshaft lobes. This is to ensure that they are not worn as well as the lifter bores for any scoring/damage that could be a concern.
When reassembling the engine, ensure that the lifters are properly aligned to the new plastic lifter guides before they are installed. If they are not properly aligned, it may damage the plastic lifter guide once it is torqued, which may allow the lifter to turn in the guide.
Low oil pressure to the VLOM can also cause AFM lifter damage. Generally most known good vehicles will have around 25 PSI or greater oil pressure at hot idle with new engine oil. If oil pressure is 21 PSI or below with new engine oil, then damage could occur to the AFM lifters.
The AERA Technical Committee
Roadmaster Engine is pleased to offer this information from The AERA Technical Committee.
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Front End Engine Rattle Noise On 1999-2009 Ford 4.0L SOHC Engines
I replaced the cam from a 2007 with AFM to that from a 2011 AFM w/ vvt. The donor motor was in perfect cond with it’s 89k miles clocked. The cam was swapped after new AFM lifters & pushrods & rocker arms & valley plate was replaced & had no affect on the ticking of cyl #1. Initial testing seems good, but after a 10 miniute test drive, damn if the ticking didn’t return. I give up. I guess the only other thing to try is retorqeing of the head & absolutely last resort would be .010-.030 longer pushrod. BTW there are 2 cylinders on an LS where the lifters can be put back in( if fallen during a cam swap) or if they needed replace & WITHOUT removing the head. The lifters on Cylinders #2 & #8 absolutely can be replaced without removing the cylinder head. You can bust me if you don’t think so. Ive done it,even made a tool to do it with. Enjoy
Thanks for your comment.
Update, the “new GM” AFM lifters I had bought for cylinder #1 still tapped after they were installed. So, I tore into this ,07 5.3L yet once again. It still sounded like it was #1 cylinder tapping. After the head was removed & lifters taken back out I wasn’t looking at a collapsed lifter. So being I just bought them, and they were not collapsed after this the 3rd attempt, assumed the problem was elsewhere. Thats when I tore down a perfectly good running 2011 AFM 5.3L motor to rob it of it camshaft. I installed it but not after some drama as this was my 1st cam swap. I put it back together finally & damnit if it didn’t STILL have the ticking sound. I’ve quit my job at this point. Ass my confidence has taken a beating. I thought I had sold, some 6 months prior, my biggest turd to date, a 92 GMC Typhoon. I’m kinda missing it at this point. Well since I am “off” now, and won’t be coming in late anymore due to working on the 5.3L nightmare. I decided to blow out the oiling bosses that feed oil in to the valley plate( I had forgotten to do this) & I was going to install the lifters from the ’11 motor also. Well 2 days later, we were pleasantly surprised not to hear any tapping of any lifters after a 5 miles semi- hard drive. I feel like a mechanic now as my confidence has been returned. Seems my ebay’d item was the turd after all. It always about who’s cheapest. But I can honestly say, it’s a good thing that
I’m 500 miles from the seller.
Thanks for sharing your experience.
Looking into 2007 LS making the rattle noise they said to delete the DOD … ???
So it’s a tear apart job ??
You’ll need to contact your mechanic to let you know the best answer.