Hard, No Start, Excessive Smoke On Start Up (Replace Glow Plugs). Chevrolet Export Chevy P42 Commercial Chassis 1998

For 1990-2009 cars

# Hard, No Start, Excessive Smoke On Start Up (Replace Glow Plugs)

Subject: | Hard, No Start or Excessive Gray or White Smoke On Start Up After Recent Glow Plug Replacement (Replace Glow Plugs)

Models: | 1982-99 Chevrolet and GMC C/K, G, P, R, V Models

| with 6.2 L or 6.5 L Diesel Engine (VINs C, J, F, P, S, Y -- RPOs LH6, LL4, L65, L49, L56, L57)

### Condition

Customers may comment on a hard start cold (normally under 32°F or 0°C) with excessive white or gray smoke on vehicles that have had glow plug replacement after January, 1999. This bulletin does not apply to original equipment glow plugs installed in production vehicles, only service plugs.

### Cause

Certain service 11G glow plugs (P/N 25168651 or equivalent) produce insufficient heat energy to the cylinder during cold starting pre-glow.

### Correction

This table may be used to help identify glow plug type.

| LOW HEAT 11G (figure 1) P/N 25168651 | ACCEPTABLE 11G (figure 2) P/N 25168651 | NEW BERU STYLE (figure 3) P/N 12563554
--- | --- | --- | ---
INSULATOR COLOR | GRAY | BLACK | BLACK
MODEL IDENTIFICATION | AC 11G////U.S.A.//// (etched in) | AC 11G U.S.A. (etched in) | AC DELCO (ink)
GLOW PLUG JULIAN DATE | AFTER 3388 | PRIOR TO 3398 | NOT APPLICABLE
GLOW PLUG DATE STAMP LOCATION | ON PLUG HEX | ON PLUG HEX | NO DATE STAMP ON HEX

Perform normal diagnostics on the hard start, gray or white smoke condition. If normal diagnostics do not lead to resolution of the symptom, determine if the glow plugs have been replaced since January, 1999. If they have, it will be necessary to determine if the service glow plugs are low heat energy units. Remember, not all 11G glow plugs are low heat energy plugs even though they do have the same part number (P/N 25168651). It is important to properly identify the type of glow plug using visual characteristics and Julian date prior to initiating any repairs.

The low heat energy 11G glow plugs can be visually identified by performing an examination of the plug. There are three identifying characteristics of these glow plugs:

1. The low heat energy glow plugs have a gray colored insulator (figure 1, item 1).
2. The hex head of the plug has a stamped in Julian date (figure 1, item 2) of 3388 or higher. The Julian date is the day of the year (such as December 3 being 337, December 4 being 338, etc.), followed by the last digit of the year (1998 being 8, 1999 being 9, etc).
3. Model identification located below the threads (figure 1, item 3) is stamped "AC 11G////U.S.A.////" (note that the low energy plugs have the slashes //// between the letters).

In figure 2, this 11G style glow plug is not a low heat energy glow plug and should not be replaced unless standard glow plug diagnostics indicate. This glow plug can be identified by these three characteristics:

1. The insulator color is black (figure 2, item 1)
2. The hex head of the plug has a stamped in Julian date (figure 2, item 2) of 3378 or lower. The Julian date is the day of the year (such as December 3 being 337, December 4 being 338, etc.), followed by the last digit of the year (1998 being 8, 1999 being 9, etc).
3. Model identification located below the threads (figure 2, item 3) is stamped "AC 11G U.S.A." (note that this model glow plug does not have the slashes between the letters)

In figure 3, this is the new style BERU glow plug (P/N 12563554) used in current production vehicles. This is not a low heat energy glow plug and should not be replaced unless standard glow plug diagnostics indicate. This style glow plug can be identified by the following three characteristics:

1. The insulator color is black (figure 3, item 1).
2. The hex head of the plug does not have a stamped Julian date (figure 3, item 2).
3. Model identification located below the threads (figure 3, item 3) is not stamped. It does have an ink identifier of "AC DELCO" and some other ink text.

If new glow plugs are required, use BERU style, P/N 12563554 (figure 3), or acceptable 11G, P/N 25168651 (figure 2). It is ok to mix the BERU style plug and the acceptable 11G style plug for service installation.

### Parts Information

Part Number | Description
--- | ---
12563554 | Glow Plug, BERU

Parts are currently available from GMSPO.

### Warranty Information

For vehicles repaired under warranty, use:

Labor Operation | Description | Labor Time
--- | --- | ---
J4767 | Glow Plugs, Replace | Use Published Labor Time