Engine makes loud noises?

The fan clutch shouldn't thud. As the temp raises under the hood, the thermostatic spring slowly engages the fan. Remove the serp belt and see if the sound goes away. If it does, one of the accessories must be going bad. NOTE: Only run the engine for a few seconds to see if the sound is gone. It will overheat. see this guide

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

Please run down this guide and report back.

I have a 2004 Silverado 5.3L and when I start the truck the engine knocks very loud. It is worse when it is cold out (30 Degrees or less). It normally goes away after a few miles or so but if i let it idle then it will last for 10 minutes or more. Also noticed that when i filled the coolent on a thursday up to the cold line I checked it again on saturday and it was about 2 inches below the cold line. No leaks on the ground and did not observe any milky substance in the oil. Dealer advised normal. I say hell no. And neither does my personal mechanic.

[quote:53b70cf3df="keth mcmahon"]I have a 2004 Silverado 5.3L and when I start the truck the engine knocks very loud. It is worse when it is cold out (30 Degrees or less). It normally goes away after a few miles or so but if i let it idle then it will last for 10 minutes or more. Also noticed that when i filled the coolent on a thursday up to the cold line I checked it again on saturday and it was about 2 inches below the cold line. No leaks on the ground and did not observe any milky substance in the oil. Dealer advised normal. I say hell no. And neither does my personal mechanic.[/quote:53b70cf3df]could be carbon buildup on the piston tops and skirts.remove spark plugs,disconnect ignition coils,using a funnel with a small tube;pour 1/4 can of GM Top Engine Cleaner into each cylinder.(this will require 2 full cans)(they cost around 10 bucks each at your dealer)allow this to sit in the cylinders at least 12 hours.crank the engine to expell the cleaner,immediately rinse the engine cleaner from the engine compartment or any painted surfaces with cold water.Install the spark plugs,change the oil and filter,then start the engine.(it will be hard to start and will smoke like hell for a little while)As for the coolant loss,have the cooling system pressure tested for leaks.

Okay I have this loud squealing coming from behind my engine I took it to my mechanic and we took off the belt and he said it coming from behind the engine when I crank it up I hear it for 1-2 mins and then when I drive and when I accelerate it get worse can u plz help me out

noises for us are very hard to do as we can't hear them. check for something dragging against converter or maybe starter problem. Something hitting driveshaft maybe as well.

What would cause my 2003 Chevy Silverado Z71 to make a loud noise that sounds like a deisel engine when I accelerate the gas?

Could be the EGR valve not opening Knock Sensor not retarding the timing,ignition timing too advanced, wrong fuel, engine carboned-up and an engine that's overheating that's creating the pinging/detonating problem