Do I really need a new engine?

[M3kanic]

Mine knocked when my solenoid stuck. Bad.

Sent from my SM-G955U using Tapatalk

 

[swingandmiss]

Another update from the dealer. They found the source of the electrical problems. The negative battery cable was severely corroded and loose. They said this would have easily caused damage to the alternator. They said they actually see this frequently. So that checks out. I asked if it could have fried the computer and they said no. So I pressed further. If the cable was bad, could that cause low voltage across all electrical systems. Yes. If all systems had low voltage at the same time, could they all report a fault to the computer at the same time. Yes. So it's feasible the computer was working fine, correctly reported errors with 4 different systems, and was then replaced unnecessarily. Most likely.

So the story is becoming clearer. It's frustrating I'm the one having to put this story together.

Now, pushing more I asked how this electrical problem could have caused the knocking, because it all happened at the exact same time, and went away at the exact same time. They say this couldn't happen. I don't believe that yet. They also said the other electrical issues weren't related, but we have a pretty good idea that they were.

@M3kanic solenoids are electrical components. I have not yet asked about the solenoids. How did you find your issue?

 

[iamdub]

Another update from the dealer. They found the source of the electrical problems. The negative battery cable was severely corroded and loose. They said this would have easily caused damage to the alternator. They said they actually see this frequently. So that checks out. I asked if it could have fried the computer and they said no. So I pressed further. If the cable was bad, could that cause low voltage across all electrical systems. Yes. If all systems had low voltage at the same time, could they all report a fault to the computer at the same time. Yes. So it's feasible the computer was working fine, correctly reported errors with 4 different systems, and was then replaced unnecessarily. Most likely.

So the story is becoming clearer. It's frustrating I'm the one having to put this story together.

Now, pushing more I asked how this electrical problem could have caused the knocking, because it all happened at the exact same time, and went away at the exact same time. They say this couldn't happen. I don't believe that yet. They also said the other electrical issues weren't related, but we have a pretty good idea that they were.

@M3kanic solenoids are electrical components. I have not yet asked about the solenoids. How did you find your issue?

I thought you said "they've already gone and checked every possible cable and tightened"? NOW they find a severely corroded ground?


I'm betting the AFM system is damaged and possibly from the electrical issues (power shortages/losses). As you said- solenoids are electrical components. So, if that has been taken care of, you need to move on to having the AFM system repaired, or better yet, deleted. Aside from violating any warranty, you could probably have a speed shop delete the AFM and tune for less than what the dealer wants just to replace a dead lifter(s) and stock camshaft and keeping the rest of the problematic AFM system.

 

[treehan77]

So they DIDNT check the battery wow.

 

[M3kanic]

I took it to a dealer. And they hooked it to the tech and I'm assuming they checked resistance through the electrical system.

Sent from my SM-G955U using Tapatalk

 

[swingandmiss]

I thought you said "they've already gone and checked every possible cable and tightened"? NOW they find a severely corroded ground?

Different mechanic. First place said they did. I'm guessing they stopped when they found the loose alternator cable. When I brought it over to GM, I asked them to look at electrical again.

I'm betting the AFM system is damaged and possibly from the electrical issues (power shortages/losses). As you said- solenoids are electrical components. So, if that has been taken care of, you need to move on to having the AFM system repaired, or better yet, deleted. Aside from violating any warranty, you could probably have a speed shop delete the AFM and tune for less than what the dealer wants just to replace a dead lifter(s) and stock camshaft and keeping the rest of the problematic AFM system.

The more I read about the AFM issues on these engines, the more I'm thinking that may be the case. So you think I need repairs to the AFM system, lifter, and potentially the camshaft?

 

[iamdub]

Different mechanic. First place said they did. I'm guessing they stopped when they found the loose alternator cable. When I brought it over to GM, I asked them to look at electrical again.

I see now. You've had two parties involved- an independent mechanic and the GMC dealership.

The more I read about the AFM issues on these engines, the more I'm thinking that may be the case. So you think I need repairs to the AFM system, lifter, and potentially the camshaft?

Yes, I'm thinking it's an AFM failure. It's not uncommon for an AFM lifter to fail and damage a lobe on the camshaft. Of course, you should have it investigated specifically and properly diagnosed. The sooner you find and fix this sort of failure, the cheaper the repair will be.

Any repairs or replacements to the AFM system requires going into the engine. I would NEVER go that far just to replace the one or few failed components or even to replace ALL the components of the AFM system unless I was not keeping the vehicle and just trying to be as cheap as possible with it. If I went that far into the motor, I'd remove all the components of the problematic AFM system and replace them with their non-AFM counterparts. This is a routine procedure and there are kits put together specifically for the AFM delete.

 

[swingandmiss]

GMC technician said he's 70% sure it's the cylinder deactivation solenoid. He said it would be highly unlikely the electrical problems caused the solenoid/lifter problem. I still think it's related, but don't know enough about the AFM system to explain it.

GMC said $4500 for a top end rebuild. At that price, I think it makes sense to have the other shop replace the whole engine at ~$7k.

 

[M3kanic]

If it is the solenoid then it's a $200 part and if you have never done it before then it should take about 4 hours if you have then about 2 maybe less.

Sent from my SM-G955U using Tapatalk

 

[swathdiver]

Removing AFM costs about $600-1500 or so in parts. I've read that a mechanic who does these daily can do it in about 3 hours though most are 2-3x that!

The computer will have to be reflashed or "tuned" as well. See if there is a speed shop in your area that can do the work and don't go camshaft crazy; unless you want to!