Technical Information

Although the glow plug is a familiar engine component, glow plug terminology often varies. The diagram below identifies the major components of a glow plug and their correct terminology.

Metal Sheathed Glow Plugs

Metal sheathed glow plugs consist of a heating coil and regulating coil which are enclosed by a special ceramic powder within the heater tube or ‘tip.’

 

 

 

 

Type of glow plug				Preheating times
Sheathed type glow plug	With one coil	Standard	e.g. Y-103-2, Y-173	20-25 Sec. to 800°C
		Quick-start-glow plug	e.g. Y-103 V, Y-106 V	15-17 Sec. to 800°C
			Y-128 T, Y-204 T S1	13-14 Sec. to 800°C
		Quick-start-glow plug	e.g. Y-112 M 1	approx. 10 Sec. to 900°C
			e.g. Y-107 R, Y-112 R 1	approx. 6 Sec. to 900°C
	With two coils	Quick-start-glow plug	e.g. Y-707 RS, Y-702 U	approx. 6 Sec. to 900°C
		Self-regulating	e.g. Y-701 J, Y-515 J	approx. 4 Sec. to 900°C

Standard Type

Sheathed single coil glow plug, which heats at a fairly uniform rate to reach its maximum temperature with a constant current consumption.

Rapid Glow (Quick Start) Type

The single heating coil installed in this design allows a higher current flow initially to promote a faster heating time. As the temperature rises the resistance of the coil rises to restrict current flow.

QGS (Quick Glow System) Type

The ‘Quick Glow System’ glow plugs have specially designed heating coils which can allow a very high current flow as soon as it is energized. Due to the extremely quick heating of these glow plugs, they require strict regulation and are only used in conjunction with specifically designed QGS control systems.

SRM (Self Regulating Metal) Type

Self-Regulating Metal glow plugs contain two coils. The heating coil at the tip of the probe provides the heat source and the second (regulating) coil allows an extremely fast warm up time to temperatures in excess of 900°C. Once this temperature is reached it can autonomously maintain a high final temperature allowing longer post heating times.

NB: None of the above parts are interchangeable

Ceramic Glow Plugs

Ceramic glow plugs are equipped with a special ceramic heating coil capable of reaching temperatures in excess of 1000°C very quickly.

Ceramic glow plugs are available in two different types:

Quick-start glow plugs: The temperature rise is very rapid – faster than in quick-start sheathed type glow plugs. The voltage generated is precisely controlled by a special control unit or glow relay.

Self-regulating ceramic glow plugs: Are also equipped with a heating and voltage regulating coil. The latter reduces the current intensity as the temperature increases.

Type of glow plug			Preheating times
Ceramic glow plug	Self-regulating	e.g. CY01	approx. 4 Sec. to 900°C
Ceramic glow plug	Quick-start-glow plug	e.g. CZ01, CX01	approx. 3 Sec. to 900°C

Thread Diameter	Tightening Torque
8mm	8-15N. m (0.8-1.5Kgm)
10m	15-20N. m (1.5-2.0Kgm)
12mm	20-25N. m (2.0-2.5Kgm)
14mm	20-25N. m (2.0-2.5Kgm)
18mm	20-30N. m (2.0-3.0Kgm)

Inspection of sheathed type Glow Plugs

In order to check the heating coil, measure its resistance as shown in the diagram (right) and based on your findings if;

• Resistance value ∞ : The heating coil is broken
• Resistance value is less than 1Ω : The heating coil is in good condition.

 

Appearance	Causes	Recommended Counter Measure
Melted Heater Tube	1. Abnormal Overheating
	a) Incorrect fuel injection timing or volume flow rate	a) Check fuel injection
	b) Abnormal combustion due to excessive lubricating oil entering the combustion chamber	b) Check valve guides and piston rings
	2. Excessive Voltage
	a) Incorrect glow plug has been fitted	a) Confirm glow plug part number is correct
	b) Faulty controller relay or glow plugs switched on too long	b) Check controller relay operation
Heating Coil Broken - Resistance	See excessive voltage above
Broken Heater Tube	Excessive turbulence or overheating due to incorrect fuel injection timing or volume flow rate	Check fuel injection timing and volume flow rate