Code P0307, knocking sound while accelerating

Tiny
EVAN LEFKO
  • MEMBER
  • 2013 CHEVROLET 1500
  • 5.3L
  • V8
  • 4WD
  • AUTOMATIC
  • 58,500 MILES
An engine code popped up 2 weeks ago on my truck. So I scanned it and it showed a p0307 code, so I erased it and took it around the block to see if it was going to pop up again and it didn't right away, but my engine started making kinda like a thumping sound coming from the drivers side of the engine witch lines up with the 7th cylinder being right by the firewall on that side. I have never heard it at idle it only happens as I accelerate and gets louder. It will stop for a bit after sitting at a red light. It also shakes at idle so I know my 7th cylinder isn't working. I took it in and the mechanic did an injector balance, changed the plugs and coil and checked compression etc, and was all good. So its mechanical and the mechanic is guessing that its a rocker arm or maybe the whole cam shaft, but i'm being told by others that it might be the lifter, either way my warranty isn't going to cover it so I took it back and did an oil change and added half a quart of transmission fluid. The knocking sound went away but my truck still shakes at idle so it didn't quite fix it, and i'm worried if I keep driving it i'm going to damage my engine, or be stuck on the way to work cause it starts knocking again or something, I have only driven it the one time since the oil change. What do you think I should do? Bite the bullet and pay to get my engine torn down or drive it a bit and see if the transmission fluid fixes the problem? Also how much money should I be expecting to pay to diagnose further and fix this?
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Tuesday, May 5th, 2020 AT 7:35 PM

1 Reply

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

First, did you mix transmission fluid with the engine oil? Also, is it a ticking or a knocking sound? That makes a big difference. The idea that you feel a rough idle could be a few things other than a major concern. An engine vacuum leak can cause a rough idle. Was the serpentine belt and the engine started to see if the sound was gone which would indicate if it is a belt driven accessory making noise?

How does the truck run once it is off idle? Has the fuel pressure been checked? Excessive fuel pressure can be causing issues as well.

Let me know these things as well as if the check engine light has come back on indicating the same or a different problem.

Until I hear from you, this link may be of interest. Take a look through it. It may help direct you are far as the noise you hear.

https://www.2carpros.com/articles/engine-noises

If it is possible, record the sound so I can hear it. Also, as far as taking the engine apart to check it is all going to be labor related and based on what is removed. For example, if a cylinder head is replaced, labor is showing 9.2 hours. The is a lot of money in time. However, if it is just removed, I can't imaging it would take more than 4 hours including inspection.

I attached a pic below that simply shows price for a new head and labor hours to replace one or both. Take a look at it for an idea on labor time.

Here is the thing. I realize that the warranty is 5 years/100,000 on the power train. Have you kept records of servicing? Have you used a Dexos approved oil? If you have, I would be contacting GM customer relations and request assistance even if it is partial help. The truck has very low mileage and this should never have happened. It's just a thought at this point.

Let me know what I can do to help. Also, if possible, let me know if the things I mentioned have been checked and if you can upload the sound so I can hear it.

Take care,
Joe
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Tuesday, May 5th, 2020 AT 8:27 PM

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