Clacking noise from chevy 6.0....

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The vehicle is a 2002 Chevy Silverado with the 6.0 V8, has 138,000 miles. It has had conventional 5w30 or 10w30 at 5K OCI since we have had it....I believe it had 30,000-40,000 miles when purchased. Went to drive it today and upon accelerating there was a metallic ticking sound coming from the engine bay. It has never made this sound before, and its only when under load. If you rev the engine in neutral it sounds normal, and there is plenty of oil pressure. It does NOT make the noise in reverse either, only when driving forward under load. I have no idea what it is, it sounds like its coming from around the engine. The brake booster was just replaced, not sure if that has anything to do with it. The engine does consume oil as well, I checked it and it was at the add line, so 1 quart low out of a 6 quart sump, not a big issue at all, we added the half a quart of oil we had laying around. The noise goes up as the RPM's go up as well, so it does correspond with RPM. Ideas?
 
Originally Posted By: xxch4osxx
Cracked flex plate?


Not sure, you car hear it pretty clearly from inside the cabin as well.
 
I once had a '72 chevy that made a noise like you described, but more like a clattering. Turns out it was a broken engine (motor) mount. The noise was the fan striking the fan shroud.

I hope you figure yours out.
 
Weak engine mount? Open the hood, have someone push the gas and brake at the same time, and see if the engine moves more than one inch. Have them do that in drive and in reverse.

However, I rarely encounter a failed engine mount on an RWD vehicle.
 
Originally Posted By: JD4440
Broken exhaust manifold bolts. Check to see if any of the heads are missing, common 6.0 problem


That's my guess.
 
You just had the brake booster changed and now.this problem? I would say you have a pretty big vacuum leak. Just because its new doesn't mean its working right. The ECU will try its best to make it idle/run right. Burns oil plus huge vacuum leak = PINGING. Block off the brake booster vacuum port at the engine (You will lose power brakes) and see if noise goes away. I'm betting bad vacuum hose or bad booster.
 
Originally Posted By: oldhp
You just had the brake booster changed and now.this problem? I would say you have a pretty big vacuum leak. Just because its new doesn't mean its working right. The ECU will try its best to make it idle/run right. Burns oil plus huge vacuum leak = PINGING. Block off the brake booster vacuum port at the engine (You will lose power brakes) and see if noise goes away. I'm betting bad vacuum hose or bad booster.


Thanks for the suggestion, but its not pinging...I am very familiar with that (Uplander in sig) its a metallic clacking noise, like metal slapping metal. Let me see if I can find a you tube video that SOUNDS like the problem. Plus, I can hold on the brake and rev it in drive and it clacks.
 
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Sucked something in the vacuum hose??? Just weird it started after booster was installed.....and it happens only under load now. Engines will make weird noises from running lean, I don't know.
 
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This is very similar....does not tick at idle but once you start to accelerate and there is some load on the engine it starts ticking....very similar situation and sounds similar as well....
>>>>>> engine tick
 
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Originally Posted By: oldhp
Sucked something in the vacuum hose??? Just weird it started after booster was installed.....and it happens only under load now. Engines will make weird noises from running lean, I don't know.


Here is the strange thing, the booster was installed 2 days ago, and the ticking JUST started. Its not my personal truck, so its been in use for 2 days and there was no noise. But as soon as I started it and drove off it started ticking. Maybe just a coincidence. Its certainly a metallic type of sound.
 
Oh ok...didn't know it was driven 2 days. I'm changing my best guess to exhaust leak. Does it do it if you brake torque it in reverse?
 
Originally Posted By: oldhp
Oh ok...didn't know it was driven 2 days. I'm changing my best guess to exhaust leak. Does it do it if you brake torque it in reverse?


No, does not do it with brake torque in reverse.
 
Originally Posted By: Merkava_4
Piston slap.


If only Merkava...its certainly not piston slap, I have that in my Accord. Its noticeable from in and outside the truck. Do these engines have any sort of valve train / rocker arm problems? It does not sound like a lower end knock.
 
I have an 01 Chevy 2500HD with 6.0 auto, and the brake booster is hydraulic - part of the same pump that runs the power steering. I don't know, but do the non-HD models have vacuum-boosted brakes?

If I had to guess, I'd go with something in you 4L80E auto transmission, check the AT fluid level, and maybe think about a filter change, fluid change and/or fluid flush.

When you have a wheel sensor problem, usually the noise comes from the ABS module when applying the brakes.
 
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