Miscellaneous Engine Components; Glow Plug; Glow Plug Troubleshooting - New Holland LS140 Workshop Manual

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SECTION 55 - ELECTRICAL SYSTEM

MISCELLANEOUS ENGINE COMPONENTS

Sheathed type glow plugs are used to improve cold

engine starting. The glow plugs draw 6.9 amps at

1. Heat wire

3. Insulation

6. Magnesium oxide powder

7. Insulating bushing

8. Center electrode

Description and Operation

A coiled, thin resistance wire is placed in the sintered

magnesium oxide powder enclosed by a stainless

steal sheath. One end of the wire is welded to the

sheath end and the other end to the center electrode.

When the key switch is placed in the "pre-heat"

position current flows to the center electrode and

through the resistance wire heating the air in the

combustion chamber.

Open Circuit

The glow plug system operates even if a glow plug is

disconnected or if it open-circuits internally because

the glow plugs are connected in parallel. An open

circuit in one glow plug will result in a greatly

extended heating cycle.

Remove the wiring connector and check the

continuity of the glow plug terminal to body ground.

The resistance should be 35 ohms. A higher reading

indicates an open circuit in the glow plug and the plug

must be replaced.

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