Exhaust Guards on GM engines

Field Service Safety Alert

Date issued: April 29, 2021

Subject: Exhaust Guards on GM Engines

Repair Urgency Level: Immediate

Repair on Next Service

Equipment Affected

Model(s): GM5.7 Engine

Component of Concern: Exhaust Guards

Concern:

Description of Incident

There was a recent incident with Flogistix that had resulted in an injury to an employee while removing the sparkplugs on a GM 5.7 engine. The sparkplugs the employee was attempting to remove took more than the normal required effort to unseat the sparkplugs. When attempting to break the sparkplugs loose the employee's lower arm near the wrist struck the exhaust guard resulting in a laceration. The exhaust heat shield guarding on the 5.7 engine can cause an additional hazard when removing the sparkplugs. If the guarding is mounted too low on the exhaust pipe it makes it harder to get good body position to remove the sparkplugs. As shown in the example photo below.

One of the main causes of sparkplugs being difficult to remove or taking excessive force to break loose the sparkplug is over tightening of the sparkplug when it was installed. The sparkplugs on the GM automotive type industrial engines have a tapered seat. The correct torque to properly seat the taper seated plug is 11 foot-pounds of torque.

The procedure for the removal and installation of the sparkplugs for the GM 5.7 engine is listed on the Field Service Wiki. It can be accessed by clicking on the attached link 1.03.011 GM 5.7 (350) Sparkplugs Installing/removing.

This is from step 5 & 6 of the procedure for removing the sparkplugs

• • Step 5: Caution must be taken when attempting to remove the sparkplug. Sparkplugs have a tapered seat, the sparkplug can sometimes break loose or free from the cylinder head at once. When attempting to remove the sparkplugs make sure that you have good footing and your hands, arms, or other body are clear of any objects when attempting the remove the sparkplugs.

  • Step 6: With the sparkplug socket all the way on the sparkplug, turn the socket counterclockwise using a long-handle ratchet making sure the pressure applied is straight and not at an angle.

At no time should an impact wrench or powered ratchet be used to install sparkplugs!

This is from step 4 & 5 of the procedure for installing the sparkplugs

• Step 4: Install the sparkplug(s) into each cylinder by threading them in by hand until the sparkplug is seated. Sparkplugs can be installed with the threads dry of lubricant. A very small amount of Never-Seize can be applied to the sparkplug threads but is not required.

  • Step 5: Install the sparkplugs by turning them in clockwise rotation until sparkplug is fully seated by turning tight. With the sparkplug fully seated in the cylinder head use a ⅝” sparkplug socket to tighten sparkplugs.

Proper torque for the sparkplug installed in a used cylinder head is 11 lb ft

Proper torque for the sparkplug installed in a new cylinder head is 22 lb ft.

If using Never-Seize only a small amount is needed on the threads as shown in the example below.

Do Not Use an excessive amount of Never-Seize on the sparkplug threads as shown in the example below. With any amount used, ensure the ceramic insulator is clean from all contaminates.

Corrective Action(s)

1. Raise Exhaust Guard

Corrective Action would be to raise the existing Exhaust Guards on the GM 5.7 engine to a higher position. Due to the design of the Exhaust Guards, the height it can be raised is limited. The upper U-bolt can be raised to where the exhaust piping starts to make the bend. As shown in the example below.

In this example below the arrows indicate showing the marks where the U-Bolts were before the guard was raised.

The example below shows the bottom of the Exhaust Guard after being raised giving more access to the sparkplugs.

2. Removal of Sparkplugs

If sparkplugs seem to take beyond normal force or needs excessive force to unseat additional measures need to be taken.

An Impact Wrench can be used to unseat the sparkplug only if allowed by the Customers Safety Policy concerning the authorized use of an impact wrench and if sparkplugs will be discarded after removal.

The preferred method of removal and installation is to use is use a longer extension on a long-handled ratchet that will extend beyond the exhaust guard to put the technicians hands and body out of the line of fire in the case of a sudden release of the sparkplug unseating. As shown in the two examples below.

Skill Level to Repair

Low

Estimated Time of Repair

The estimated time to raise the Exhaust Guard should be 15 minutes per side

Tools, Equipment, or Parts Required for Corrective Action

All employees performing this Corrective Action shall be required to have the listed tools to perform job tasks:

• 9/16" deep socket (Corrective Action 1)

• Long handle ratchet (Corrective Actions 1 & 2)

• 6" minimum extension (Corrective Action 1)

• 5/8" deep or spark plug socket (Corrective Action 2)

• 14" minimum extension or combined extension length (Corrective Action 2)

• (4 ea) 5/16" x 3" u-bolts for replacement guard mounts if existing u-bolts are excessively corroded / seized (Corrective Action 1)

Note: This policy or alert is subject to change in the future as additional risk mitigation methods are tested and approved for use in the field.

Approvals

Field Service approved by: Charles Crenshaw, VP Field Service

Date: 4/29/2021

Engineering approved by: Aaron Baker, VP Compressor Engineering

Date: 4/29/2021

EHS approved by: Michael Southard

Date: 04/29/2021