4.8 Engine Noise

[meade01]

I have a 2005 4x4 with a 4.8 in it and it used to run quiet and now it has a ticking/knocking sound while it is idling. When you rev it up the noise goes away. I was wondering if anyone has any ideas. It makes the truck sound like junk, but it runs perfectly fine and has good oil pressure with no knocking going down the road. Thanks in advance.

[C. Charles Hahn]

I BLAME AFM!!!

 

Oh wait....

 

Just figured I'd get that out of the way now before some of the actual loud-mouth trolls come-a-knockin'.

 

In all seriousness, it could be a bent rod, a lifter, or any number of things. If you can't pinpoint where it's coming from with a mechanic's stethoscope I would suggest taking it to a mechanic that can diagnose it. Also, if it's been a while I'd go get a fresh oil change and also look to see if there's anything in the oil that comes out or in the filter.

[Metro12]

I had a 1991 Silverado that had the same noise. I checked my push rods, as that was my guess. Ended up getting progressively worse, and determined it was a lower engine bearing.

[Gurrzt]

I believe what you are describing is called "piston slap".

[dsr611]

I believe what you are describing is called "piston slap".

I believe he would have figured it out in 5 years since he posted.

[WilliamBos]

I really wish people would update these threads.