Another 5.3 with AFM bites the dust ~ Chevrolet Active Fuel Management Problems

Discussion in 'GM Powertrain' started by hblock72, Jan 19, 2013.

  1. El Jefe

    El Jefe New Member

    Correct me if I have this wrong, I'm not the car expert, and am not trying to pass myself off as an engineer or anything. It looks to me (and others) as if the lifters begin to slam down against the cam lobe when cold due to excess play, air in it etc. This comes in the hints of ticking and some misfire when cold, but they often won't bring the car in until it's virtually undriveable. It clears up quickly but will do this every time it's cold. After a period of the lifter banging against the cam lobe, the roller at the bottom can't take any more and quits turning, or binds. Then the cam lobe gets torn down and the car comes in with 3 or more codes.
     
  2. RayVoy

    RayVoy Epic Member 5+ Years 5000 Posts

    Quite a theory, GM/Chev V8 engines have always made a little lifter noise when cold, even the new ones. And, the thinner the oil, the more likely to do it.
     
  3. El Jefe

    El Jefe New Member

    I am seeing this from numerous fleet managers and others everywhere. It is mostly the 5.3's and it is not specific to one bank or lifter. Originally people were saying that it's the needle bearings in the tappet failing. That appears to not be the case. I have seen a few where the roller is shot, the cm lobe is shot and the roller still rotates freely. I also see them where the roller is binding. I am really screwed as I have no strategy to keep these vehicles in long-term service at this rate. If this keeps up, they will hit the auction line while only a year old and that's almost impossible to sell to County administration, but at the rate things are going I will have a mountain of documentation to prove that replacing these lemons would save a lot of money. Still, it's up to several of us to figure out a long term fix if at all possible so that these can remain in service without these failures repeating. We must be 100% sure why these failures occur and what it would take to permanently mitigate this problem, even if it's expensive.
     
  4. El Jefe

    El Jefe New Member

    We had some of the older Suburbans and Silverados with the 5.7s and they were really not costing much money. Tires, belts, fuel pumps and when they got really old intake gaskets and spiders. Wish they still were still built like that, but everything is trade off.
     
    thegawd likes this.
  5. RayVoy

    RayVoy Epic Member 5+ Years 5000 Posts

    What are you using to lubercate these engines?
     
  6. El Jefe

    El Jefe New Member

    Mobil 1 0W-20 or 0W-30, can't remember which.
     
  7. El Jefe

    El Jefe New Member

    I am not that hands on, but this involves a lot of money and Fleet Services said they use some new oil that's super thin. They were told they could use Mobil 0W-20 and I believe 30. I am not sure which one they use. There are others but we have had Mobil 1 for at least 15 years and one of the two is being used. With all of the VVT engines in use now, there are charts all over the tool boxes down there and they have to be very careful to use the right oil or the engines run awful and throw codes before they get out the gate. Like I said before, things are different then they were 25 years ago.
     
  8. RayVoy

    RayVoy Epic Member 5+ Years 5000 Posts

    That's why I asked about the oil, they are very fussy.
     
  9. El Jefe

    El Jefe New Member

    I appreciate your input. If and when we come up with something worthwhile, I will share it here.
     
  10. OLEJOE

    OLEJOE New Member

    Exactly what I plan to do. Have thought about going ahead and get another engine, rebuild it without the AFM and have it ready to go when needed. Can probably get one at a salvage yard for a decent price.
     

Share This Page

Newest Gallery Photos