Engine knocking

white1500 · April 16, 2014

My dads 2006 with a 4.8 had been knocking nonstop for about half a year now and he just got it fixed. This is something that I had never heard of before but the mechanic replaced a filter or seal in the oil pump. It cost my dad about $400 because its 4x4 and the front diff added to the difficulty, but was quoted $200 if RWD.

So far his truck has been perfect aside from the noise, and now its back to being its old quiet self! I didn't believe in the solution at first but was gladly proven wrong.

Definitely look into this if you have the ticking/knocking issue that is usually associated with the lifters post warmup.

Westlotorn · September 11, 2014

I have had two issues with noise on start up. My 2001 Denali 6.0L had piston slap on start up. A very fast ticking at low volume on start up that went away as soon as heat hit the pistons from running 30

seconds or so. This issue is well documented and will cause no issue other than noise on start up for the life of the engine. Our Denali did this new and at 90,000 when we sold it.

I just had to open up my 2002 Tahoe 5.3L with 135,000 miles. Noise on startup, this one was a deep

knocking, not a light tapping/ticking. The deep knock turned out to be the O ring on the Oil pump

where the pick up tube bolts to the pump.

This O Ring is a $3.00 part and the O ring fixed this knock on start up but to fix this you have to drop the pan. On my 4x4 you drop the front differential and then the pan. Straight forward job but I had 8 hours into this going

slow, cleaning all parts and assemble time. Zero leak afterward so far, 2,000 miles and the knock is

cured. Read up on proper torque sequence for the oil pan, and exactly where to use the silicone on the corners. Many have had leaks on this, I used a Fel Pro gasket and read the instructions and had no issue.

A pitman arm puller is important as you will need to drop the steering arm from both the pitman and

idler arm to get room for the front differential to come out. I hooked a bungee to the steering rod to pull it towards the front bumper after I popped it off the Idler and Pitman arms to gain space for dropping the front diff. This is the perfect time to change the

idler arm and keep your steering tight. I used a new Moog idler arm, it came with a cool grease tube so it can now be lubricated without dropping the front rock pan.

FYI, prior to doing this job I was able to use the truck without the knock by starting the engine, waiting a count of 5 and turning it off prior to the deep knock starting. Wait 5-10 seconds and restart.

Most times this worked, my theory is that it sucks the oil up prior to shut off. On shut off this oil drains down and helps seal the Oring. I did this for 2-3 months while I was avoiding this big repair.

New Oil Pan Gasket, GM O ring and an Oil Change about $100. and I was done. Hope this helps some of you.

NVGMman · October 16, 2016

Old thread yet still relevant. Like Westlotorn, I was also having a knocking that came from the lower part of the engine. Tried changing the oil, as I thought the zMax had made oil too thin, added Lucas oil stabilizer but no luck. Changed oil again then added Restore but still no luck. Decided to drop the pan suspecting it was a bad bearing. I was nervous to do so as I had never gone that deep into engine yet was not too bad, just time consuming. With my friend's help, we checked all the rod bearings (all good) and checked the oil O-ring on the pick up. Put back together thinking I was going to buy a new block as everything looked good but fortunately all noises were gone for good.

Looking back, that o-ring was the culprit even though it looked good when I replaced it. When the knocking occurred, the ring must have been letting air into the system which explains why my low oil warning would come on even with the dipstick reading full. Frustrating what a headache a $2 rubber o-ring yet glad it's fixed.

Side note, interals where very clean as I do my oil changes every 5k miles with high quality oils (depending on what's on sale at Autozone) and use a K&N HP2011 filter which is bigger than stock.