5.3L Gas engine sounds like Diesel

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by natehawes, Aug 13, 2009.

  1. natehawes

    natehawes New Member

    I have a 2006 Chev 1500 w/ the 5.3L V8. I've only had the truck about a month and I love it. However, while driving tonight I began to notice a new sound. When I'm accelerating I hear a noise coming from the engine compartment, or possibly under the truck, that sounds very similar to the sound a diesel engine makes. The sound goes away if I go full open throttle and if I let off the gas. It only appears when I'm doing normal acceleration.

    It was happening after driving for a while so it would not be cold engine knock. The only real mod the engine has is a cold air intake. I run 85 octane gas and have not had any problem before tonight.

    Does anyone have any idea what it could be? Maybe engine knock, heat shield loose, headers, exhaust, something else???
  2. yotchie

    yotchie Rockstar 100 Posts

    well im sure there are a number of things it could be. the only time i have heard a gas engine sound like a diesel was when a friend of mine bought a new ford and it had a defect ( aside from the oval lol) he drove it 900 km and found out somethin like the cam or crank was not tightened properly. however his sounded like a diesel when it idled. you may want to get that checked

    good luck.
  3. retired2001

    retired2001 Epic Member 5+ Years 5000 Posts

    Welcome to the site! As far as the "diesel" soiund, have you recently filled up with gas? It might be "bad" gas (water or dirt). I'm sure that some of the more mechaincal folks on the site will be able to give you more advice. Good luck!
  4. heavy chevy

    heavy chevy Epic Member 5+ Years 500 Posts ROTM Winner

    bad gas switch to at least 87 and pour some lucas gas treatment in it. Or some sea foam
  5. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    I agree with the gas, 85 octane?? Never seen that, the lowest is 87 I always thought. That could be the problem
  6. natehawes

    natehawes New Member

    Yes, I did just get gas about 15 miles before I started to hear this new sound. Believe it or not, here in Utah they do sell 85 octane as the standard gas. So maybe I just got some bad gas. I put some Lucus Oil gas treatment in today and now I'm driving as much as possible to get rid of this tank. I'll fill her up with 91 octane next time and see if the sound goes away.
  7. heavy chevy

    heavy chevy Epic Member 5+ Years 500 Posts ROTM Winner

    hope that was the fix to your problem let us know what you find out
  8. willbradfan

    willbradfan Rockstar 100 Posts

    You have to be careful what station you get gas at, my dad is a petroleum eng. and he has always told me about the difference it makes with quality gas etc. They make 85 octane gas for higher elevations, as their is less oxygen present. I've been running my 96 suburban for the past 2 years on 85octane and no problems what so ever.
  9. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    I would never run 85 octane gas and I live at 5000 feet. If you run 85 octane your engine pings. You can't hear it because your knock sensors hear it first and retard the timing until the ping goes away. Do your truck a big favor and run the correct octane. You and your truck will be happy and you will see an increase in your gas mileage a well! :)
  10. willbradfan

    willbradfan Rockstar 100 Posts

    I am at 7000ft where I am at in Colorado and I have talked to several guys at the dealership and they have told me that it will run just fine, i don't know if it would be worth the extra money for 87 anyways. I'll have to try a tank of 87 octane sometime, just might be an expensive fill up or a half tank fillup

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