I’m trying to diagnose a squeaking noise on a 2015 and it’s turning out to be a head scratcher.

It sounds like it could be a loose heat shield and is strongest from the right rear area of the engine bay. It’s consistent in that it’s there immediately upon startup and doesn’t fade or change in frequency or intensity with engine temp. It does change with RPM but isn’t noticeable above about 1200 RPM whether inside or outside the cabin - I suspect it’s still there and is just being drowned out by the exhaust (glass pack).

I’ve ruled out all the heat shields I can find and exhaust joints. I did find the joint right before the tail pipe outlet was loose so I removed the tail pipe just to make sure it wasn’t somehow resonating back to the front. I removed the external heat shield on the right manifold, verified all the bolts for the exhaust manifold were tight, and pulled the engine to trans lower bracket to inspect for a cracked flex plate or loose TC bolts - all good. I’ve tried gently pushing/prying against brackets, engine and transmission mounts, and other random places trying to get a change in noise to narrow it down - no luck. I pulled the belt and it’s still there. I’ve also used the scan tool to run tests on the MDS solenoids and intake runner valve to see if it changes and nothing.

I’m at a loss because process of elimination seems to have narrowed it down to an internal noise, but unless there’s oil starvation to the rockers, I don’t see how it could be. I don’t think oil starvation is an issue at this point because there’s no other indicators such as chatter or misfires.

I’d appreciate any ideas to further isolate the source. Thank you.

 

Well I’m not 100% positive about it, but I think the noise was due to damaged rockers and valve stem tips (see photos).

For clarification - I initially described it as a loose heat shield noise because if you can imagine the sound of a heat shield rubbing on something and creating a higher pitched “nails on chalkboard” type of sound, the noise is comparable. However I would say a better description is an idler pulley that only squeaks once per revolution instead of constantly.

I ended up removing the valve cover and reinstalled the coils so I could run the engine - the noise was much louder. I removed the rocker arms and shafts for inspection and found that the intake valves for 3, 5, and 7 all had rough/damaged tips. The rockers as well had damage. With the engine running, I could see oil flowing through the push rods and passages to the shafts, so I’m not sure what could’ve caused the damage - maybe an oil starvation problem previously fixed.

Thankfully I’m not on the hook for this repair. The customer had just bought the truck and after explaining what I thought it was, they contacted the dealer and the dealer agreed to take care of it.

I decided to try and test my theory during reassembly - I dabbed some grease on the valve stem tips before installing the rockers, then listened closely at the first start up. The exhaust made it hard to hear but I think for the first few seconds, the noise was either gone or faded. Hopefully the customer will let us know what the dealership finds and if it ended up being the valves.

These pics are of the #3 intake valve and rocker - they were the worst of them all. It’s kind of hard to see (best pic I could get) but the stem has a very rough tip. The rocker looks like it probably had worse damage at one point but has smoothed out.

 

Update:

I never received confirmation on whether or not the damaged stems and rockers were the source. Apparently the dealership installed a replacement engine, but I don’t know if it was used/reman or new, and the truck hasn’t been back in our shop since.

This is one of those things that comes to mind every now and then so I just wanted to conclude this thread while I was thinking about it.

 

I replaced manifolds a few month ago so was surprised to here a tick back so soon(I'm an idiot and installed factory manifold instead of shorty)

Tick became much worse over a few days and now it has a squeal element to it when i accelerate. After I get to highway speed for a bit I can park it and the noise as died back down to what sounds like the normal exhaust leak, but those first few minutes sound worse and worse. The squeal is starting to scare me....my hope, maybe still manifold leak and a pulley happened to go out at the same time....but I'm starting to think a lifter is going out. I've heard they fail in two ways, one which damages the cam and stays loud by the bearing going out, the other has something to do with the lower end and gets quite when the oil pump fills it up. These are my thoughts so far, anyone have any ideas? Planning to do cam swap for a texas speed setup if it is the lifters but don't want to spend that if I have something else wrong😅

Also, curious if bad lifters can cause the rocker arm issue you described?

 

There’s a number of ways the rockers and stems could’ve been damaged the way they were. As of now I still haven’t heard if a cause was determined nor has the truck returned.

The short answer is yes, bad lifters could be responsible for that kind of damage, but I’m inclined to think there had to be additional debris involved if that’s the case. A bad lifter + a broken push rod that’s bouncing around inside the cover, perhaps.

Or maybe the rockers were off for some reason and got damaged, then reinstalled anyway, causing damage to the valve stems.

I’ve only looked at a few 5.7 hemi’s with misfire or driveability issues. Of those, 2 were discovered to have worn cam lobes; but I’ve heard about plenty that have collapsed lifters.

​​​​​The most direct way to diagnose is to pull the valve covers for visual inspection.

 

Mine ended up just being exhaust manifold again. One of the bolts stripped the thread out of the bolt and was making a hellacious noise. Sounded like air intake leak or belt slipping along with a gnarly knock, ended up being stripped manifold bolt. Helix thread repair to save the day, super easy to fix....on passenger side at least.