Engine sounds - rocks in a cup

C

coleman

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Dec 4, 2011
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It's been fairly trouble free driving with my 02 TB. I have almost 176K miles on it. I noticed a couple days ago that it's developed a weird noise that sounds like rocks being shaken in a plastic cup. It only makes the noise at just below 2K rpm, and not even all the time, but it's very noticeable when does happen. Other than that, the engine is runs quiet and nice and smooth. Valve issue?

Anyone have an idea?
 
Quick update. I took the truck around the block a few times, revved it in neutral, in drive, etc.. No noise. No ticking, no knock, no rocks. I couldn't reproduce it. The engine is smooth. Argh...
 
Could be noisey lifters or rocker arm sticking because of oil gunk over the course of 170k. Mine has 250k and get occasional clicking from the valve cover area. After an oil change they quiet down then get noisy when it's time for a oil change.

What i do to remedy this is add some type of oil conditioner after an oil change and seems to help a bit.

I heard of putting seafoam in the crankcase to help break down gunk never tried it though but might work well since seafoam is a powerful cleaner. You will have to change the oil after though.

Get a long screw driver and put your ear to the handle and set the tip to around the valve cover area (kind of like a stethoscope) and see if you can isolate where the ticking is coming from if it ever comes back.

Another thing it could be is a cracked exhaust manifold, these trucks are known for that and cause clicking and ticking.
 
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I agree with Jeremy. I personally add a quart of Lucas Oil with my oil changes. I've had a ticking for months now, replaced all my lifters even though when me and my bud inspected them they were fine even at 130K. He used his stethoscope and thinks I've got a crack in my manifold. I'm replacing it with an '09 one (better design, flows better, more HP) when I get back to the states 3 months.

And yes, ticking, knocks, and etc. are common on this platform unfortunately, but with a lil detective work you can find the issue and then go about resolving it
 
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Could have been your water pump...they sound exactly like you described. There's a chance that you heard it because the fan was engaged and under a higher load, likely deflecting the angle of the impeller, then it relaxed and the noise went away.

I have never heard a water pump make a noise like the 4200, when it's worn, it sounds like you're dragging a coffee can full of nails down the street.
 
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You said in your post that you drove it around the block and heard no noises from the engine.
I know it's a huge pain on this platform, but check for loose flywheel bolts/cracked flywheel.


Never mind, re read post, noise went away
 
The best thing is when it does the noise again is to record it and post it up. Try to see/feel where it's coming from.

Another thing that's possible is the timing chain tensioner. If the noise is coming from the front top of the valve cover at the oil fill, that would be it.
 
gmcman said:
Could have been your water pump...they sound exactly like you described. There's a chance that you heard it because the fan was engaged and under a higher load, likely deflecting the angle of the impeller, then it relaxed and the noise went away.

I have never heard a water pump make a noise like the 4200, when it's worn, it sounds like you're dragging a coffee can full of nails down the street.
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Agree!

Water pump starts out as only making noise at certain rpm and conditions
Eventually it will start doing it all the time, at all rpms.

Listen to see if the noise is near the center of the engine.
Unload the belt tension and spin the pulley slowly by hand, with and without pressure against it.
If you feel any roughness regardless as to how tight the bearing might feel, you have found the source of the noise.
 
Thanks, guys. I noticed yesterday that it starts when the engine is at full temp. I replaced my water heater a year or so ago when found it was it was wobbling. I suppose it could be bad again. I hope not. Total pain to replace and I wasn't planning on doing it again.

I'll check out the noises again as soon as I get someone to rev the engine while I'm under the hood and it certainly can't hurt if I throw in some Lucas Oil in the meantime. I'll let everyone know what I find. Man, I wish GM would come out with a new TB. I keep holding out, hoping that they'll sell it in the US, but at this rate I think a Colorado is in my future.
 
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Capote said:
I agree with Jeremy. I personally add a quart of Lucas Oil with my oil changes. I've had a ticking for months now, replaced all my lifters even though when me and my bud inspected them they were fine even at 130K. He used his stethoscope and thinks I've got a crack in my manifold. I'm replacing it with an '09 one (better design, flows better, more HP) when I get back to the states 3 months.

And yes, ticking, knocks, and etc. are common on this platform unfortunately, but with a lil detective work you can find the issue and then go about resolving it
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capote ill bring you my extra manifold for free its only 2 hours away.
 
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Mike w said:
capote ill bring you my extra manifold for free its only 2 hours away.
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That'd be cool, you're really only 2hrs away?
 
I think I have something similar... rocks in a cup and a can full of nails sounds right.
Video is here:


The sound is very irregular, coming and going, and can only be heard when idling. Hope you can hear it. My wife has a real stethoscope at home so I took it to the truck and listened. I'm pretty confident the sound is coming out of the water pump... However when I was changing my belt I tried to wiggle the shaft that the fan is on and it didn't move at all, no play whatsoever. What exactly is it inside the pump that makes sounds like that?

Did the thermostat a few weeks ago, coolant almost new :Banghead: Could the new coolant have let something loose and help the pump to the grave?
 
Did you feel on top of the valve cover next to the oil fill cap? I had a similar sound and only at idle, which was my timing chain tensioner. It's a bitch of a job.

To confirm if it's the water pump, take off the belt and start the engine.
 
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Mooseman said:
Did you feel on top of the valve cover next to the oil fill cap? I had a similar sound and only at idle, which was my timing chain tensioner. It's a bitch of a job.
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Yes I have and I haven't heard anything weird from there. Fortunately. The chain job is insane :)
Navigating a real stethoscope in there while the engine runs is a good adrenaline excercise... it gets into the fan or belt while you have it in your ears and your ear drums go to hell :2thumbsup:

Mooseman said:
To confirm if it's the water pump, take off the belt and start the engine.
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Yeah, should have done it when I was changing the belt :bonk:How long can the engine run without accessories? It takes maybe 20 secs before the sound I'm trying to diagnose starts to be audible enough.
 
I'd say you could run it for 5 minutes if it's not already hot. That should be enough.
 
Well, it was the water pump, but not a bad bearing. The water pump is leaking and the knocking I'm hearing is the low coolant running through the engine and sloshing around with the air pockets. I never would have thought about this.

I replaced my water pump about three years ago. The job wasn't that bad, but I just don't have the time now. Since it's getting worse and worse, off the shop she goes. That leaves me with only three other fluid leaks on this thing. Unfortunately, there's only so much money I'm going to pour into the old gal, but I can't risk getting stuck on the highway.

Thanks for all the suggestions, guys. Invaluable information.
 
Well, I didn't burp the system after replacing the thermostat... maybe I should do that first before I get into changing the pump ;)
Actually, the idea that it could be air in the system also crossed my mind, as I was listening to it. But I have no overheating issue (it's close to 0 °C here, though).
 
dkvasnicka said:
Well, I didn't burp the system after replacing the thermostat... maybe I should do that first before I get into changing the pump :wink:
Actually, the idea that it could be air in the system also crossed my mind, as I was listening to it. But I have no overheating issue (it's close to 0 °C here, though).
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No high engine temps here, either, and it's been in the 80s and 90s. Live and learn.
 
Found out I have a cracked radiator, too, which is why I'm losing coolant like crazy. $630 to replace it. Add to that the water pump, the leaky transmission, the rack and pinion, and my mystery oil leak that eats quart of oil every couple weeks and I think it's time to part with the ol' gal. :( Sad days...
 
BlazingTrails said:
Man are you mechanically inclined? you can fix all those issues yourself for a small fraction of what you would have to pay a shop. Plus you can avoid a car payment?
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I am. I've done most of the work on my TB myself down through the years, but my family is always on the go and I'm short on time and patience, plus my back can't take bending over an engine anymore. Besides, I've been driving it going on 15 years. It might be nice to have a new car. Sometimes you have to live a little.
 
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coleman said:
I am. I've done most of the work on my TB myself down through the years, but my family is always on the go and I'm short on time and patience, plus my back can't take bending over an engine anymore. Besides, I've been driving it going on 15 years. It might be nice to have a new car. Sometimes you have to live a little.
Click to expand...


I can understand that for sure. Do you think you will stick to the GM family?
 
Minor math correction - 13 years, unless you had a time machine and bought a 2002 in 2000 :P
 
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Gotcha. Darn you had to have a real early one and shoot holes in my attempt at being funny!
 
Sparky said:
Gotcha. Darn you had to have a real early one and shoot holes in my attempt at being funny!
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Hehe. Sorry! Yeah, when I got mine, I think there were only two on the lot. Fell in love with it immediately. She's been real good to me. Going to miss her. Best vehicle I ever had.
 
Snag: Looks like the Colorado's bed can't handle 4x8 sheets of plywood without placing them on a couple pieces of 2x6 braces to raise them over the wheel wells, and even then there's nothing to support the back half of it. Have to think about this. I may just have to pull the trigger and then and figure something out later. The TB can easily haul sheets of plywood. I'll miss that capability.
 
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I think I have a winner. Tried to burp the cooling system, no air in there. Took the belt off, check out the play in the water pump:

I'm quite nervous that it takes so long to ship things from the US to EU because the play seems massive to me and I'm anxious to fix this as soon as possible... It also probably explains why my vibrations went away a little when I bought a new belt. The belt probably straps the pump a bit better and does not allow that much wobble while driving...

Edit: looks like the water pump is the same that Hummer H3 (which is available here) uses and I'll be able to buy it here...
 
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Fixed! :wooot::Lager Louts:
Man that fan clutch bolt and getting the shroud and the fan out... I haven't felt that desperate in a while :Banghead: I think the pump was still original. Had to use hammer to let the bell pulley and the pump itself loose.
It also fixed my vibration problem. She's smooth like my 6 mo old son's butt now! :D
Ready for the winter, I hope. Fixing this kind of stuff without a garrage in 43 °F is not that much fun...
 
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