Jump to content

new strange knock, 2014 AT 5.3L

tig488

By tig488
in Troubleshooting & Recalls

 Share

Recommended Posts

tig488 Enthusiast

tig488

Posted
Posted

hi guys, I have a 2014 AT 5.3L with 109K miles.  last week I started hearing a strange knocking noise coming from underneath the truck.  it was during a cold start on a really cold morning.  I could hear it also from the topside.  it sounds like horse steps or empty coconut halves bring hit together, if that makes sense.  its not fast, its actually kinda slow, it goes up a little bit with the rpms.  funny thing is, when it happened I stated googling things and found the vacuum pump TSB/recall so I called GMC.  they ended up replacing it for free and wouldn't you know it the noise stopped. well a week later and its back.  its not all the time.  I got underneath it while it was running but can't really pinpoint it.   it kinda sounds like its from the oil pan.  its time to change the oil so ill start there.  maybe its really low, but I haven't gotten a low oil pressure light lately.

 

M1ck3y Senior Enthusiast

M1ck3y

Posted
Posted

I'm no mechanic but it sounds like you could be describing rod knock.

 

It sounds like you rely on a low oil pressure light for maintenance purposes? That's not what the warning light is for; it's there to prevent catastrophic engine damage. 

CamGTP Senior Enthusiast

CamGTP

Posted
Posted

A rod knock would be very loud and by now the engine would have grenaded from it. Plus the oil would be full of metal if that let go.

 

I'd have to hear the noise to try and figure it out better. Just seems odd that the new vacuum pump made it stop but then it came back a little while later.

  • Thanks 1
M1ck3y Senior Enthusiast

M1ck3y

Posted
Posted
22 hours ago, CamGTP said:

A rod knock would be very loud and by now the engine would have grenaded from it. Plus the oil would be full of metal if that let go.

 

I'd have to hear the noise to try and figure it out better. Just seems odd that the new vacuum pump made it stop but then it came back a little while later.

 

Horse steps, coconuts halves being hit together? imo that sounds loud, but your the mechanic 😉

tig488 Enthusiast

tig488

Posted
  • Author
Posted

no I don't rely on my light for maintenance.  this engine is notorious for being low on oil one day and full the next. I couldn't tell you how many times I've checked the stick to see it bone dry, add a qt, and drain 8 qtz when I change it a week later. I even posted about it a long time ago.  

 

this isn't very loud,  just barely audible over idle.

richard wysong Senior Enthusiast

richard wysong

Posted
Posted

maybe you should let it rest longer when you check the oil. its possible the oil drain passages are stopped up somewhere in the engine. I would take it back to the dealer and have them check the vacuum pump

tig488 Enthusiast

tig488

Posted
  • Author
Posted

oil pressure is perfect, dead center.

 

changed the oil today, drained 6 qtz,  still doing it but doesn't appear to be as loud.  its not continuous.  it does it a few times then stops, then does it again a few times then stops.  I don't get it.  guess ill take it to the dealership and let them see if they can figure it out.

Supreme Pizza Senior Enthusiast

Supreme Pizza

Posted
Posted
1 hour ago, tig488 said:

oil pressure is perfect, dead center.

 

changed the oil today, drained 6 qtz,  still doing it but doesn't appear to be as loud.  its not continuous.  it does it a few times then stops, then does it again a few times then stops.  I don't get it.  guess ill take it to the dealership and let them see if they can figure it out.

 

 

 

If your headed to the dealership then it will be extremely expensive and may not even fix the problem.

 

Before you do that, try "Motor Medic". It takes 5 minutes and might solve the problem.

 

I solved a LOUD lifter tick and a low oil pressure issue with this stuff that costs...... $5.

 

I would flush the motor, and change the oil filter brand, and oil weight to something a little heavier. (check manual for options)

 

I recommend not flushing the motor unless there is a need, and I recommend not changing the oil weight, unless there is a need.

 

 

 

66e902c3-d4ac-4dec-b17b-91e3ac572b5f.4fe

richard wysong Senior Enthusiast

richard wysong

Posted
Posted

it would help if you could get a better location of the noise. take a long screwdriver and use it as a stethescope by putting the handle against your ear and probing with the blade different spots on the engine. check all the belt driven stuff as well as the engine but watch out for the fan blade

Supreme Pizza Senior Enthusiast

Supreme Pizza

Posted
Posted
24 minutes ago, richard wysong said:

it would help if you could get a better location of the noise. take a long screwdriver and use it as a stethescope by putting the handle against your ear and probing with the blade different spots on the engine. check all the belt driven stuff as well as the engine but watch out for the fan blade

 

 

FH07OCT_DIASTE_01-2.jpg?resize=350,350

 

fuel-injector-listen.jpg

 

M1ck3y Senior Enthusiast

M1ck3y

Posted
Posted
7 hours ago, richard wysong said:

you know thats what the dealers going to do at $150+ per hour. they aren't magicians 

 

They won't even do that. If there's no codes, there's no problem..   

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Latest Articles

  • Posts

    • Atlas
      Wow I'm in a pickle. (Broke down truck) and a story.

      By Atlas · Posted

      Thanks - I wasn't quite caffeinated this morning. 2:1 makes sense, turning the crankshaft 360 degrees will turn the cam 180 degrees, and had I done that, the cam's dot would be at 6 and the crank's at 12 again.   I went ahead and took the sprocket off anyway, aligned everything dot-to-dot including the balance shaft just for s&g. I'm glad I did because I discovered no Loctite on the timing sprocket bolts. Maybe it's not required, but at only 20 ft-lb torque spec, those bolts aren't in there very tight. Cleaned and reassembled with some thread locker and torqued.   A general observation: Less is more with RTV. If a little doesn't stop a leak, a LOT probably won't, either. RTV is thinly veiled revenge, in a tube...      
    • richard wysong
      Wow I'm in a pickle. (Broke down truck) and a story.

      By richard wysong · Posted

      The timing marks are ok, that is #1, you can turn it over until they line up and it won't change anything, the crankshaft turns twice for every camshaft revolution, I have always set up SB Chevs as your pic shows using a straight edge
    • Atlas
      Wow I'm in a pickle. (Broke down truck) and a story.

      By Atlas · Posted

      Someone's been here before.... There is a receipt for a 3-piece timing set, purchased earlier this year.   Is this picture something, or, nothing?   I have the timing cover off and my crank is perfectly TDC and the keyed gear's locating mark is dead on 12 o'clock.   The cam gear locating mark is also at 12 o'clock. Now, I'm not an expert, but all the install guides say the two locating marks should meet and be perfectly aligned when installing a timing set. The mark on the crank should be dead on 12:00 and the cam gear's mark should be dead on 6:00, and both marks should be perfectly vertically aligned.   I believe the timing gear is keyed or has a dowel that ensures it can only be installed on the cam in one position, so I have to believe the cam is out of phase somehow. At the very least, with a triangular bolt pattern, it can only be installed in one of 3 different positions.   Before I pulled the front cover, the truck was running alright, no service engine soon lights except an occasional P0172 / rich condition. Timing -16 timing at idle (should be +16), and total -35% fuel trim, two conditions I haven't been able to figure out.   In related news, my injector tested pretty well, wasn't leaking, but I had it rebuilt anyway, and it's on it's way back to me.         Along with this discovery, the good and bad:   Good: The oil pan seal appears undamaged.   Bad: -The timing cover has been reused, and the positioning dowels have been broken. That could explain some of the leaking. -Some kind of white paste or grease was used to try to seal the oil pan seal and timing cover (since wiped off..). -Then, someone globbed silicone all over the front of the cover and also buried the ckp sensor in it. But, they didn't put any inside the cover or use RTV to try to seal the oil pan seal with the timing cover (good).
    • Grumpy Bear
      PF63 Oil Filters Going Away?

      By Grumpy Bear · Posted

      The guy that owns K&P filters last I checked in with him has over 300,000 miles on his Dodge base Hemi using his own 35 micron absolute stainless mesh filter from its first oil change.    The GM study I've posted a dozen times shows the relationship in engine life based in multiples of base units, not miles or years. That is the base unit is the number of miles the motor ran using the reference filter efficiency.    The above two paragraphs dismantle anecdotal arguments IF one changes oil often enough to prevent particle formation and the motor is in otherwise good shape. That is not full of silica (no air filter) or suffering a metallurgical issue that is not part of the lubrication discussion. Poor heat treat in example.   Data from UOA's I've reviewed from more than a few engines can show remarkably broad variations in oil cleanliness using the exact same filter over the course of an engines life.     Lastly there is the common sense of it. Wear debris WILL circulate the engine BEFORE it ever sees a filter in route to that filter and WILL harm the pump which NEVER sees filtered oil.    Alpha question then becomes, given the facts, how long do you believe is a reasonable service life from a vehicle you are certain you will not pass down? That is the junk yard will be it's resting place when you're done with it? (the moral issue most don't care about).    Omega question is then how diligent are you prepared to be in general mechanical, air & oil maintenance? Preventing particulates and keeping them sufficiently dilute; preventing the precursors from generation, amalgamation and precipitation.    If I get a good look at the engine bay of a vehicle I have a fair idea of the owners commitment to the inside of the power train. That 30 micron WIX is still more efficient than a sieve.                 
    • Tyler Gibbs
      PF63 Oil Filters Going Away?

      By Tyler Gibbs · Posted

      It also depends on what criteria someone is using for “best” when talking filters.  Are we going off best efficiency?   Best quality/QC?  Etc. because the two may not mutually exclusive.  

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...