Timing Chain Tensioner TSB

msm20032003 · July 17, 2006

I have a 2003 Silverado Reg. Cab Automatic with a 4.3 V-6. I asked a question a week ago or so about a flex pipe TSB. I took my truck to the dealer and they found out that it is not an exhaust problem; it is the Timing Chain tensioner. Can you tell me more about this problem/TSB. Can it cause problems? The dealer wants $900 to fix it and I am not sure that I want to do this just yet if it is not going to cause any problems...It is really annoying though.

bobcat5544 · July 17, 2006

Document ID# 1572398

2003 Chevrolet Chevy K Silverado - 4WD

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Subject: Supplement to 03-06-01-024B 4.3L LU3 L35 Timing Chain Tensioner - kw balance chain cover gasket noise pump rattle shaft warranty #PIP3048A - (11/30/2004)

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The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Condition/Concern:

Rattle-type noise coming from the engine at approximately 1800 to 2200 RPMs - The spark, rattle-type noise may be caused by torsional vibration of the balance shaft. The 2003 and 2004 4.3 L LU3 Vin code X engines will not accept the service timing chain tensioner fix as per bulletin 03-06-01-024B. Prior to June 2003 all 4.3 LU3 engines will accept the service timing chain tensioner as per bulletin 03-06-01-024B. This PI is a supplement to Bulletin 03-06-01-024B and applies only to engines built between June 2003 and September 2003.

The production timing chain tensioner was put into all engines beginning with the Julian date of 251 (September 8, 2003); the engines on or after this date code should not have customer concerns of balance shaft rattle. (The engine unit number and Julian date code locations are explained below.)

Recommendation/Instructions:

Complete the proper SI diagnostic for engine noise. If detonation noise is present, perform detonation/spark knock diagnostics first. If the Balance shaft rattle noise has been verified on a 2003 or 2004 4.3L LU3 engine the dealer will need to check the engine Julian date. The engine Julian date can be found on the Engine Unit Number bar code label. The Engine Unit Number label can be found on the right side of the oil pan, left rear of the cylinder head, or the right front of the valve cover. This label has a fifteen character number on it. The 9th, 10th, and 11th digit of this 15 character number is the Julian date. The Julian dates are listed below with their proper service fixes.

JULIAN DATE 153 (JUNE 2, 2003) TO JULIAN DATE 200 (JULY 19, 2003)

1. If the engine is between the Julian dates of 153 to 200 and the customer concern of balance shaft rattle has been verified, there is no service fix and the engine will need to be replaced.

JULIAN DATE 202 (JULY 21, 2003) TO JULIAN DATE 227 (AUGUST 15, 2003)

1. Between the Julian dates of 202 and 227 there are mixed configuration blocks. The configuration of the block can be identified by an orange or purple dot found on at the rear of the block near the balance shaft boss and next to the knock sensor.

A. If the block has an orange dot, the block has non-machined timing chain tensioner bosses and will not accept the service fix or a production timing chain tensioner. If the customer concern of balance shaft rattle has been verified the engine will need to be replaced.

B. If the block has a purple dot, the block is fully machined and it will accept the production timing chain tensioner. The dealer will need to use the 2004 Model Year LU3 replacement parts for the Timing Chain Tensioner Bracket, Timing Chain Tensioner Bolt, and the Timing Chain Tensioner Shoe to install the production timing chain tensioner. The parts from bulletin 03-06-01-024B will not fit.

JULIAN DATE 230 (AUGUST 18, 2003) TO JULIAN DATE 251 (SEPTEMBER 8, 2003)

1. If the engine is between the Julian dates of 230 and 251 the block is fully machined and it will accept the production timing chain tensioner. The dealer will need to use the 2004 Model Year LU3 replacement parts for the Timing Chain Tensioner Bracket, Timing Chain Tensioner Bolt, and the Timing Chain Tensioner Shoe to install the production timing chain tensioner. The parts from bulletin 03-06-01-024B will not fit.

Alternative Method Of Identification:

Remove the front cover and inspect the front of the block.

If the timing chain tensioner bosses are present and are not machined, the surfaces of the bosses will be rough in appearance with no holes drilled. Neither the service kit or production kit will fit. Replace the engine.

If the timing chain tensioner bosses are present and machined, the surfaces will have a flat machined surface with holes drilled, the upper hole threaded for a bolt, the lower hole is machined smooth for a locator pin, see SI information for Timing Chain, Sprockets, and/or Tensioner Replacement for proper identification. Install the production timing chain tensioner for the 04 model year.

If there are no bosses cast into the block the service kit should be installed as per bulletin 03-06-01-024.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

Models:

(03 04 C1 C2 K1 K2 S1 S6 T1 T6 M1 Chevrolet Silverado Astro Express S-10 Blazer) and (03 04 C1 C2 K1 K2 S1 S6 T1 T6 M1 GMC Sierra Savana Safari Sonoma Jimmy)

Draenor · July 17, 2006

I feel sorry for the folks who have orange dot engines and ones produced before Aug 18 2003.

msm20032003 · July 17, 2006

That was slightly confusing......How do I know what all that means? The dealer wants to do it....but I think I have an X in my VIN Number....I am not spending a grand for nothing... I think my truck was manufactured in Feb. 03......if that makes any difference........I sure am NOT replacing my engine......So does this cause any problems....or is it just annoying? I read it again and it says it is only for engines made between June and September of 2003. What about engines made in Jan.-May of 2003?

Draenor · July 17, 2006

That was slightly confusing......How do I know what all that means? The dealer wants to do it....but I think I have an X in my VIN Number....I am not spending a grand for nothing... I think my truck was manufactured in Feb. 03......if that makes any difference

<{POST_SNAPBACK}>

I think the "X" means bad......You need to replace the engine, from what I read. Check the engine unit number, as described on the TSB to get the date.

msm20032003 · July 17, 2006

The TSB thing that bobcat put up is for models with engines built between June and September. My truck was built in Feb., so I know my engine was built before that. Is there a TSB for engines before June? Once again, will this cause engine damage or anything? Or, is it just an annoying noise?

I think I need to see TSB 03-06-01-024B not the supplement to it.

msm20032003 · July 17, 2006

Is there anyone who can provide me with TSB 03-06-01-024B ?

msm20032003 · July 17, 2006

Never mind, I found a copy. It says for VIN's X and W. The supplement said all engines prior to June would work. My truck was built in February of 2003. I am reading the 03-06-01-024B and it says it contains revised warranty information compared to 03-06-01-024A. I wonder what was changed.

bobcat5544 · July 17, 2006

03-06-01-024B all it tells you is how to due the job

Subject: Rattle Noise in Engine (Install Timing Tensioner Kit) #03-06-01-024B - (03/04/2004)

Models: 1996-2003 Chevrolet Astro, Blazer, Express, S-10, Silverado

1996-2003 GMC Jimmy, Safari, Savana, Sierra, Sonoma

1996-2001 Oldsmobile Bravada

with 4.3L V6 Engine (VINs W, X -- RPOs L35, LU3)

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This bulletin is being revised to change warranty information. Please discard Corporate Bulletin Number 03-06-01-024A (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.

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 Information

Part Number

Description

Qty

12458911

Chain kit

1

89017257

Tensioner

1

10220906

Oil pan gasket

1

88893989

O ring and gasket kit

1

3754587

Water pump gasket

2

89017259

Cover

1

Parts are currently available from GMSPO.

Warranty Information

For vehicles repaired under warranty, use:

Labor Operation

Description

Labor Time

J1944