Noise
#1
10-06-2007, 10:12 AM
Noise
I have a rattle-type noise occuring in my engine compartment at 1400-2200 RPM. It only occurs when the trans is in gear and the motor is warm. It does not seem to be coming from the exhaust.
One mechanic dismissed it as noisy lifters, but don't these typically make more noise in a cold engine and quiet down as it warms up?
I see there is a TSB pertaining to the timing chain tensioner making a noise like this. Has anyone experienced this problem? And does it make sense that it would only do this after warming up?
One mechanic dismissed it as noisy lifters, but don't these typically make more noise in a cold engine and quiet down as it warms up?
I see there is a TSB pertaining to the timing chain tensioner making a noise like this. Has anyone experienced this problem? And does it make sense that it would only do this after warming up?
#2
10-06-2007, 01:18 PM
RE: Noise
There actually is a TSB on this very thing. Most likely it is the balance shaft making the noise. There is a quite extensive repair procedure that can be done, but... Let me read through it and see how long the TSB is. I may be able to post the whole thing.
#4
10-06-2007, 03:46 PM
RE: Noise
Here's the beginning of the TSB for this repair:
So yeah, it is the balance shaft and is corrected by installing a timing chain tensioner.
Engine - Engine Rattle at 1,800-2,200 RPM's
Bulletin No.: 03-06-01-024C
Date: August 30, 2006
TECHNICAL
Subject:
Rattle Noise In Engine (Install Timing Tensioner Kit)
Models:
1996-2003 Chevrolet Astro, Blazer, Express, S-10, Silverado and P Models
1996-2003 GMC Jimmy, Safari, Savana, Sierra, Sonoma
1996-2001 Oldsmobile Bravada
with 4.3L V6 Engine (VINs W, X - RPOs L35, LF6, LU3)
Supercede:
This bulletin is being revised to add additional models. Please discard Corporate Bulletin Number 03-06-01-024B (Section 06 - Engine/Propulsion System).
Condition
Some customers may comment on a rattle-type noise coming from the engine at approximately 1800 to 2200 RPMs.
Cause
The spark, rattle-type noise may be caused by torsional vibration of the balance shaft.
Correction
If detonation noise is present, perform detonation/spark knock diagnostics first.
Install a new tensioner assembly kit using the procedure below.
Remove the engine front cover. Refer to SI for engine front cover removal procedure.
Remove the crankshaft sensor reluctor ring and line up the timing marks on the crank gear and cam shaft gear.
Remove the camshaft gear and chain. For model years 1996-1998, remove the crankshaft sprocket using J 5825-A.
Pull the shipping pin and discard. Remove the nylon timing chain tensioner blade from the timing chain tensioner bracket.
Position the bracket on the front of the engine. The upper two attaching holes of the bracket will line up with the center two engine front cover bolt holes. The lower bracket holes will line up with the engine front cover alignment holes.
Use a hammer and the J 46165 Pin Driver to install the dowel pins through the two lower holes in the bracket and into the engine block. Make sure that the bracket is held firmly in place before proceeding.
For model years 1996-1998, install a roller-type timing chain set. Install the crankshaft sprocket using the J 5590 Crankshaft Gear Installer. Install the timing chain around the crankshaft sprocket and position the timing chain to the driver's side of the engine.
Install the nylon timing chain tensioner guide onto the timing chain tensioner bracket pin and position the top of the guide under the tab at the top of the bracket.
Install the camshaft sprocket into the chain and then to the camshaft. Install the bolts finger-tight. Make sure the timing marks are aligned, then tighten the camshaft sprocket bolt.
Tighten
Tighten the bolt to 25 N.m (18 lb ft).
Install the crankshaft reluctor ring.
Install the engine front cover and place a washer under the two center cover bolts that extend through the tensioner bracket. These washers are required to maintain the proper crush on the engine front cover seal.
Tighten
Tighten the bolts to 12 N.m (106 lb in).
PARTS:
Bulletin No.: 03-06-01-024C
Date: August 30, 2006
TECHNICAL
Subject:
Rattle Noise In Engine (Install Timing Tensioner Kit)
Models:
1996-2003 Chevrolet Astro, Blazer, Express, S-10, Silverado and P Models
1996-2003 GMC Jimmy, Safari, Savana, Sierra, Sonoma
1996-2001 Oldsmobile Bravada
with 4.3L V6 Engine (VINs W, X - RPOs L35, LF6, LU3)
Supercede:
This bulletin is being revised to add additional models. Please discard Corporate Bulletin Number 03-06-01-024B (Section 06 - Engine/Propulsion System).
Condition
Some customers may comment on a rattle-type noise coming from the engine at approximately 1800 to 2200 RPMs.
Cause
The spark, rattle-type noise may be caused by torsional vibration of the balance shaft.
Correction
If detonation noise is present, perform detonation/spark knock diagnostics first.
Install a new tensioner assembly kit using the procedure below.
Remove the engine front cover. Refer to SI for engine front cover removal procedure.
Remove the crankshaft sensor reluctor ring and line up the timing marks on the crank gear and cam shaft gear.
Remove the camshaft gear and chain. For model years 1996-1998, remove the crankshaft sprocket using J 5825-A.
Pull the shipping pin and discard. Remove the nylon timing chain tensioner blade from the timing chain tensioner bracket.
Position the bracket on the front of the engine. The upper two attaching holes of the bracket will line up with the center two engine front cover bolt holes. The lower bracket holes will line up with the engine front cover alignment holes.
Use a hammer and the J 46165 Pin Driver to install the dowel pins through the two lower holes in the bracket and into the engine block. Make sure that the bracket is held firmly in place before proceeding.
For model years 1996-1998, install a roller-type timing chain set. Install the crankshaft sprocket using the J 5590 Crankshaft Gear Installer. Install the timing chain around the crankshaft sprocket and position the timing chain to the driver's side of the engine.
Install the nylon timing chain tensioner guide onto the timing chain tensioner bracket pin and position the top of the guide under the tab at the top of the bracket.
Install the camshaft sprocket into the chain and then to the camshaft. Install the bolts finger-tight. Make sure the timing marks are aligned, then tighten the camshaft sprocket bolt.
Tighten
Tighten the bolt to 25 N.m (18 lb ft).
Install the crankshaft reluctor ring.
Install the engine front cover and place a washer under the two center cover bolts that extend through the tensioner bracket. These washers are required to maintain the proper crush on the engine front cover seal.
Tighten
Tighten the bolts to 12 N.m (106 lb in).
PARTS:
#6
09-13-2008, 11:04 PM
RE: Noise
my truck is doing this. it sounds like its spark knocking yet i have new plugs and wires, new dist. and cap and ran seafoam through it with no help. how should i go about getting the stealership to fix it....
#7
09-13-2008, 11:43 PM
RE: Noise
ORIGINAL: muleman
my truck is doing this. it sounds like its spark knocking yet i have new plugs and wires, new dist. and cap and ran seafoam through it with no help. how should i go about getting the stealership to fix it....
my truck is doing this. it sounds like its spark knocking yet i have new plugs and wires, new dist. and cap and ran seafoam through it with no help. how should i go about getting the stealership to fix it....
ZR2003
what oil did you use ???
#9
12-18-2008, 04:27 PM
RE: Noise
I am reviving this thread because I have been experiencing this problem for the past several months and it has gotten progressively worse. My first thought was that it is the serpentine belt tensioner, and I still think that is what it is.
My question is this: if it is not replaced, will it break? Is the sound a warning that it is failing soon? I plan to take a trip within the next month, and if that is the case, I will need to do it. Thanks for any help anybody can provide.
My question is this: if it is not replaced, will it break? Is the sound a warning that it is failing soon? I plan to take a trip within the next month, and if that is the case, I will need to do it. Thanks for any help anybody can provide.
#10
12-18-2008, 04:52 PM
RE: Noise
I think the tensioner is like $20.
Worst case scenario, tensioner stops turning, belt continues to turn, eventually the heat will eat the belt and the belt will break in two. No doubt at the worst posible time.
To find th source of the noise I use a hot dog stick. One that you use over a camp fire to cook hot dogs. I stick one tong on the suspect part and put my ear to the handle end. carefully move it around and listen. You'll know when you find the problem part.
Worst case scenario, tensioner stops turning, belt continues to turn, eventually the heat will eat the belt and the belt will break in two. No doubt at the worst posible time.
To find th source of the noise I use a hot dog stick. One that you use over a camp fire to cook hot dogs. I stick one tong on the suspect part and put my ear to the handle end. carefully move it around and listen. You'll know when you find the problem part.