Timing Chain Tensioner TSB??

[big JC]

This is a tsb for owners who experience a chatter noise from the front of the engine at around 1800-2200 rpm from years 1996-2004. The fix is to add a timing chain tensioner to fix a defect in the balance shaft. Apparently gm discontinued this as a warranty because the noise eventually comes back. my question is how many of you have the noise, did you get the timing tensioner fix or not, and will this shorten the engines life? I have read all I could find on this subject, and of course the info is varied. By the way not all blocks can accept the tensinoer and the tsb calls for replacing the engine if it can't.

[Smiliesafari]

My knowledge on this is like "none". It's the first I've heard of a timing chain tensioner on a 4.3. It would seem to be more prudent to replace a stretched chain with a new one. Could somebody explain more clearly exactly what the problem is with the balance shaft?

[mdmead]

I've never heard of this either. When I read the thread title, I thought to myself "I didn't think the 4.3 had a tensioner for the timing chain!" Definately haven't heard of adding one. I never noticed any noise on my '96 in the 160K+ miles I drove it. I'd be interested to hear more about this though.

[MountainManJoe]

By the way, I get a bit of chatter from the engine when it's cold too. But I've read this is a normal sound to hear until the oil gets warmed up and properly distributed over lifters and other moving parts.

But you say it even happens when hot right? Maybe a blocked oil passage being would produce a similar effect.

[big JC]

I am not computer savvy enough to steer you guys to the exact forums I was on. What I learned is this... there is infact a tsb# and procedure for this and it was revised more than once. From a specific month in 04 all 4.3 engines get a timing chain tensioner. If you google "timing chain tensioner tsb - gm-trucks" you can find all the specifics. I just regurgitated that the tsb is to correct a faulty balance shaft and am unsure if that is the case. I have been trying to pin down a noise issue with my van that led me on this trail. What would a stretched timing chain sound like and is it likely an 03 with 106k would have a stretched chain?

[MountainManJoe]

Unless there was some related catastrophic failure, it seem very unlikely that a chain would stretch after only 100k doesn't it?

[astroturf]

I will say that the last two days upon arriving on a job site. That after recording arrival time, turning off the AC, and getting out of my 05. That I have walked away from it with it running. Yes, It was that quite to these deaf ears that I had to check my pocket for keys.
DOH, It's still running.
Jim

PS TSB Number?

[MountainManJoe]

I can't say I've done that before, turf. But my gf did manage to lock the keys inside with the engine running.

You can find them here: http://www-odi.nhtsa.dot.gov
And here:
The Center for Auto Safety (http://www.autosafety.org/)

Technical Service Bulletins (TSBs):
GM publishes TSBs to help dealers diagnose & repair problems on vehicles.
Some dealers will let you view TSBs. You can access TSB summaries via
NHTSA's Website at www.nhtsa.dot.gov.
NHTSA's Technical Information Services (http://www.nhtsa.dot.gov/cars/problems/trd/), which can be contacted through
NHTSA's Auto Safety Hotline at 1-888-327-4236, can also send a particular TSB once you identify it from NHTSA's Website or its computer printout. ALLDATA provides free access to TSB summaries & sells copies of TSBs listed on its Website. You can also buy them from HELM, Inc. Call 800-782-4356 for ordering information. For your use, we have listed some of the more comprehensive TSBs on your vehicle. Check the above sources for other TSBs.

NHTSA (http://www.nhtsa.dot.gov/)
TECHNICAL SERVICE BULLETINS

The Division has a microfiche collection of the technical service bulletins issued by manufacturers to their dealerships from 1968 to 1985. Bulletins from 1986 through 1993 can be accessed on optical disc and later bulletins can be requested through TIS Staff or may be viewed on the Alldata System, after calling up the appropriate vehicle make, model and model year. Many of these service bulletins contain the instructions which motor vehicle manufacturers provide for their dealer repair services.

The Technical Service Bulletin Database is available online via the NHTSA Web Page. Information for a particular vehicle may be retrieved by entering the appropriate Make, Model and Year. Some of the components can be searched as well.

[MountainManJoe]

Oops I think I misunderstood you. The number is 03-06-01-024B

[astroturf]

Lots of Good Info there Timeless.
Thanks, Jim

PS Just saw your addition.
Thanks Again

[v8famvan]

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)
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This bulletin is being revised to add additional models. Please discard Corporate Bulletin Number 03-06-01-024B (Section 06 -- Engine/Propulsion System).
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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 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 the bolts to 12 N·m (106 lb in).

[big JC]

Hello v8famvan, I would be curious to know, have you performed this procedure and what would be the dangers of driving a van making the noise but has not yet had a tensioner installed? Any input on the matter would be greatly appreciated

[v8famvan]

I have not personally done this update procedure on a vehicle. I have only seen it done on a very few vehicles in my 20 years at a dealership. No real harm will occur if it is not done - just some noise, unless it is really loose & wears thru the cover.