2005 Suburban knocking noise

barton261 · May 25, 2017

I have been having a knocking noise that comes and goes at random. It doesn't matter if the engine is cold or warmed up. When the noise is present it gets louder and faster with acceleration or if in park by simply pressing the gas peddle. The noise as I previously stated comes and goes and when it's not present the engine sounds normal. In either situation I have no loss of power. Engine has 197k. I had the transmission rebuilt last summer which is irrelevant, but I keep up on maintenance. I've had it at multiple mechanics and they keep my vehicle for a week and can never reproduce the sound.

It's worth noting that the vehicle has been like this for 3 years and counting it's a daily driver as I have 7 kids and we have taken numerous family trips cross country with the vehicle like this with no issues.

Below is a YouTube video link I recorded of the sound. The video is from the passenger side of the vehicle. It is much louder lower like in the wheel well area. When I moved the camera up to the top of the engine under the hood it was quieter but still noticeable. When riding in the vehicle it is noticeable from there as well and seems like it is coming from the passenger side then too. Any help is GREATLY appreciated! Thank You.

dhmtbiker9 · June 14, 2017

My 2013 Sierra with 47,000 miles is making that noise. still haven't found cause but it definitely gets worse as oil wears out. Guy at garage told me change my oil every 3000 with full synthetic. I asked him why so early when synthetics should go at least 5000 he had no answer but I think its a way for the motor to stay happy while warranty so they wont have to fix. I put a post while ago with video sound also.

mj0528 · June 14, 2017

Try some seafoam/MMO in gas and crankcase. Quietened mine a ton!

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Supreme Pizza · June 28, 2017

Doesn't sound like piston slap to me. Probably in the bottom end. Might be a rod or wrist pin. You can pick up a mechanic stethoscope very cheap on eBay or Amazon. With this tool, you can pinpoint the area that the noise is coming from. Bad water pump bearing? Coming from the cylinder head? Coming from the bottom of the case?

I would also try:

Change the oil filter brand a few times in the same week, checking for less or more noise. Different filters provide different oil volumes and oil pressures. They are only a couple bucks at Walmart. Also try changing the oil grade/type at the same time. Ya, try SeaFoam. Try putting premium fuel in it (just for fun). Start doing things that are easy and simple. If one of them happens to hit the target and solve the problem, then your good to go. Its cheaper and easier to try little things before sending the vehicle to a "repair shark" stealership mechanic.

muddkatt · June 28, 2017

Check to see if the honey comb in the catalytic converter has broken loose. Hard to tell from your video, but on my 01 it sounded like a rod knocking. I hear exhaust leaks on your video too. Probably manifold bolts that have snapped off would be my guess on that noise.