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What's that noise,,, FOUND IT :-/

4xcrazy

4xcrazy

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This just started the other day, I heard it two days ago while taking the kids to school, it was nice out, rolled the windows down and shut off the ac. Roll by curbs and walls, heard the echo.. not good I think.

So I crawled under it just a bit ago, took this video, not much to see, more of an audio thing I need assistance with. I hate to think of a rod bearing going out, just thought I'd run it by you guys.

It's the '05 Avalanche with the 5.3 engine, ran full synthetic oil most of it's life, regular changes, (always reminded with the dash board computer) 130,xxx miles currently, still runs, idles smooth and has power, but this noise increases with engine rpm's and also gets alittle louder as well.

I'm more familiar with the older 350's, getting to know this thing, but it's taking time.

Thoughts?


 
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might be loose converter bolts or cracked flywheel try put trans in gear and see if sound changes,,,,just something to try
 
I was going to double check the tq converter bolts as we just had the trans rebuild a few months ago, but the sound doesn't really change when it's put into gear.
 
I was considering it to possibly be a rod bearing, but the knock isn't really consistant with it's sound, it seems like something like that would be a constant, same type of sound knock or something.

Also since the oil pump is up front on these, I was curious if anyone with previous experience with these engines know what they tend to do when they start to fail. Pressure is fine at about 45 or so @ idle and goes up with throttle.

Still going to do alittle more research and poking around to see if I can see anything before dropping the oil pan, something, gut feeling of something is telling me to avoid dropping the pan.

At first I thought it was an idler pulley or something, I dunno, kind of has me bummed about this.
 
Grab the belt, I suggest it not be running when you do that, and try to turn the engine back and forth with the belt.

You won't, of course, but if you have some slack, its may be the harmonic balancer.

I think the belt pulley is on the other side of the rubber on that engine.......

Otherwise, I'm gonna go with flywheel/converter Just sounds too erratic for a rod or main.

And it does not sound like the timing chain hitting the cover.

Don't know if it will help with this, but you could try the broomstick trick. You know, put the broomstick against parts of the engine and the other end against your ear. Remove the broom part, of course.

It will be lots louder when you get close with the stick.
 
I still have to check the torque converter bolts, that unfortunately requires removal of the starter.. :-/ but I did eliminate any possibility of any belt driven accessories & pullies by removing both belts and starting it, noise still there...

Off to the next item on the list.:crazy:
 
Fordum said:
Don't know if it will help with this, but you could try the broomstick trick. You know, put the broomstick against parts of the engine and the other end against your ear. Remove the broom part, of course.

It will be lots louder when you get close with the stick.
Click to expand...

I did this with a screwdriver, long one, learned that trick a long time ago, that's how I determined it was near middle/front of the engine.

Still going to check tq converter bolts regardless, I know certain noises travel through the engine alittle weird.
 
Well crap,, torque converter bolts were all tight and no sign of any cracks in the flexplate. :frown1:

This is annoying, I'd hate to keep driving it though and whatever it is decides to grenade while driving down the freeway and then require a complete engine replacement.
 
Yeah, I thought that, but it really isn't a consistant noise with what I would consider matching up with the stroke of a piston, every time, like the noise of a bad rod bearing of lifter, those are usually a constant noise every time the piston hits up or down.

This sould ovbiously has a pattern, but a werid one.
 
Well, dropped the pan, it was leaking anyways, nothing seemed loose , damaged or out of place, wondering if the oil pump is just making noise now, wouldn't think it would be the timing chain, 130k miles really isn't all THAT high with today's engines.

I guess if I decide to replace the oil pump, the timing chain is right there behind it, do it all while It's apart.
 
Going to put it all back together this week, not sure why I didn't think about it before removing the oil pan, but once back together, I'm going to remove the torque converter bolts, push the converter back away from the flexplate and then start it... See if the noise is still there, basically eliminate the transmission from the rotating assembly and see if I'm possibly getting an echo noise travelling up through the crank.

This trans was just rebuilt a few months ago, we'll see how it goes I guess.

If It's still doing it, I guess I'll button it up ang get added towing insurance on our insurance policy.. :D

Priced out a new oil pump, juuuuust a bit more expensive than the older ones,,, plus the cost of gaskets, coolant, kind of an expensive guess that the oil pump would be making noise. Hate to spend that kind of cash on a guess..
 
Well, didn't really have the cash this week for the gaskets and new oil pump, so I reinstalled everything back on with new oil pan gasket, new oil, didn't mess with anything really, but now it doesn't have ANY oil pressure.

Guess I'm changing out the pump tomorrow,,, :-/
 
Sounds to me like a cracked flexplate. I would unbolt the convertor and push it backwards then start the engine and listen for the noise and i'll bet it changes.

This will also eliminate it as being in the trans if the noise is still there.
 
I was planning on doing that once everything is back together, we decided to go ahead and change out the pump, even though after getting in there and seeing the condition of the pick up tube o-ring seal, I think that little piece is what caused lack of pressure. It was dry and crusty looking, and since I had to remove the pick up tube to get the splash tray off the bottom end, I don't think it sealed when it was reinstalled.

Also since the pump is out of the way, the timing chain is getting changed, just a tad bit more slop in it than I like.

Gonna be gettin it all back together today.
 
New oil pump, old one wasn't bad, I'm pretty certain it was the o-ring that failed during reassembly the first time, sucks, but well, there's a new pump now.

Got most of back together and sealed p enough to fire it up to make absolute sure there was oil pressure before the complete engine was reassembled, there was, instantly, but the knocky noise was still there.

So I guess it's on to the flexplate. :doah:

This thing is giving me a headache. :what:
 
Buttoned everything up, Jenn drove it to take Elora to dance class tonight, not more than 20 miles total, it came home sounding worse...

Still gonna disconnect the torque converter and use the new stethascope to try to pinpoint it's true location.

This was taken real quick, on the lower setting on the phone to be able to send to a few friends via text... But you can definitely hear a difference from the first video...

Still sound like a flexplate? :confused:

 
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Disconnected the torque converter from the back of the engine, fired it up,,, it's something in the engine. :frown1: sounds louder up towards the front, really can't determine if it's up towards the top or down on bottom, it's that loud even with the stethoscope.
Going to let it cool and pull spark plugs just to see if I see anything abnormal, not thinking I will, but I'm running out of ideas other than pulling the engine out or near completely apart.

Whatever is going on, it's messing with the idle as well now, does a bit of surging, I plugged my scanner in and first off got a random misfire generic code 300, not sure if it was from this truck, or a previous vehicle I checked out, but it won't show on here anymore and the check engine light isn't nor has it ever come on.
 
Have you removed the serp belt and fired it up yet to make sure it isn't any of the accessories making noise?
 
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