Stuck DOD AFM valve lifter
Thread Starter
Intermediate
Joined: Oct 2002
Posts: 30
Likes: 0
From: Baily CO
Stuck DOD AFM valve lifter
I wanna kick myself.... I have been reading about all the issues being caused by Active Fuel Management and been putting off disabling it with my HP tuners and now its too late. Last week I was out in my Z51 (bone stock) and hit an on ramp to the highway and all of a sudden heard a bang and a loud tap, tap ,tap coming from the right side of the motor and reduced power. Right away I knew, the dreaded DOD AFM stuck lifter problem.
This morning I pulled the valve cover off and confirmed the #6 Intake valve is stick partially open.
Anybody have knowledge on this issue on the C7? I have found many Chevy trucks and SUVs with 5.3 engines on line, but not many LT1s.
Sad thing is warranty expired last February...
Maurice
This morning I pulled the valve cover off and confirmed the #6 Intake valve is stick partially open.
Anybody have knowledge on this issue on the C7? I have found many Chevy trucks and SUVs with 5.3 engines on line, but not many LT1s.
Sad thing is warranty expired last February...
Maurice
Last edited by molobo; Nov 15, 2020 at 01:03 AM.
Melting Slicks
Joined: Aug 2004
Posts: 2,339
Likes: 483
What kind of knowledge are you looking for? It definitely happens on the c7’s. It’s a large repair especially if it damaged the cam lobe. Don’t drive it anymore and start looking into parts if you’re capable of working on your own car. If not, find an experienced shop. If you have a good service history with your dealership you might be able to get some goodwill assistance if the car isn’t modified. I see it’s tuned so I assume it is.
Thread Starter
Intermediate
Joined: Oct 2002
Posts: 30
Likes: 0
From: Baily CO
What kind of knowledge are you looking for? It definitely happens on the c7’s. It’s a large repair especially if it damaged the cam lobe. Don’t drive it anymore and start looking into parts if you’re capable of working on your own car. If not, find an experienced shop. If you have a good service history with your dealership you might be able to get some goodwill assistance if the car isn’t modified. I see it’s tuned so I assume it is.
The car is not tuned (YET) I use HP tuners on my other modified C3
.
So here's the scoop, I pulled the intake and the VLOM ( the vale galley where the AFM solenoids live) Inspected the cam lobe and it appears to be fine.. My question is has anybody had any luck freeing the lifter by any other method other than pulling the head.
I've seen a method where you put a small rod through the top of the engine just above the lifter on an angle and hit the rod with a hammer until the lifter releases. I'm not so sure I want to do that as I feel it can cause other problems.
Its looking more and more like I just need to pull the head remove and replace both lifters in that cylinder. And maybe take the opportunity to install some nice headers while I'm in there to make my self feel better. HAHAHA
Just looking for advise from other C7 owners.
Last edited by molobo; Nov 16, 2020 at 02:05 AM. Reason: spelling
Former Vendor
Joined: Feb 2012
Posts: 26,512
Likes: 351
From: ST. CHARLES IL
We've seen a lot of these go out on LT1 cars, 5.3s and LT4s. They all go bad sooner or later. I'm not sure how you feel about modding but now is a great time to just do a cam swap. However, if that's not your cup of tea, you'll need new lifters, head gaskets and heat bolts. We usually have good dod lifters laying around if you need a set.
Moderator emeritus
Joined: Jun 2001
Posts: 18,599
Likes: 3,954
From: Jacksonville Florida BWO Dayton, Cincinnati, Bloomsbury NJ, Cincinnati
2015 C7 of the Year Finalist
As long as I'm working on the extended warranty, I leave "innards" alone. However, I have never left my "innards" too alone after the warranty. You sound like you're in the later case and I see getting rid of the DoD and while you're in the area, maybe a tweak of the cam and stuff associated with it (springs, lifters, and things). That's what I'd do in this case. The V4 is great for highway driving and soft pedaling the gas. It is seamless and hasn't caused me grief (yet). What it adds is minor and it was GM doing the EPA Gubmint requirements. Big deal to Gm but I don't think I'd miss the V4.
Elmer
Elmer
Thread Starter
Intermediate
Joined: Oct 2002
Posts: 30
Likes: 0
From: Baily CO
Exactly what I have been thinking. I haven't done any modifications on this car due to the warranty, but now is the time. I am going to maybe install headers and a vortech or procharger supercharger system, I've been toying with this idea for awhile now have heard of lots of power gains and realy havent heard any bad consequences. I don't think I'm going to mess with the Cam not really needed with these options. I'm just going to replace the two DOD lifters, head gasket and head bolts on the right bank, not going to do the DOD delete mechanically but just in the computer. Today I got all the way down to the head bolts.
Any thoughts or comments?
Maurice
Any thoughts or comments?
Maurice
Instructor
Joined: Sep 2016
Posts: 207
Likes: 34
Exactly what I have been thinking. I haven't done any modifications on this car due to the warranty, but now is the time. I am going to maybe install headers and a vortech or procharger supercharger system, I've been toying with this idea for awhile now have heard of lots of power gains and realy havent heard any bad consequences. I don't think I'm going to mess with the Cam not really needed with these options. I'm just going to replace the two DOD lifters, head gasket and head bolts on the right bank, not going to do the DOD delete mechanically but just in the computer. Today I got all the way down to the head bolts.
Any thoughts or comments?
Maurice
Any thoughts or comments?
Maurice
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Moderator emeritus
Joined: Jun 2001
Posts: 18,599
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From: Jacksonville Florida BWO Dayton, Cincinnati, Bloomsbury NJ, Cincinnati
2015 C7 of the Year Finalist
I don't know about the weight but I'd get rid of DoD completely on the engine to go FI. You want everything solid in there when you are going higher in the CR. At least that's my thoughts.
Elmer
Elmer