glow plug heating

[blown]

just wandering how long the glow plugs should keep heating for,mine is a 95 patrol and we are trying to sort out a few glow plug probs,mainly the time they heat for,at pres they stay heating for over a min,auto sparky trying to work it all out .please help

[Justin_M]

(i might be wrong, i havent worked on a qg diesel before) BUT, i'd dare say theres a coolant temp sensor soley for the use of the glowplug timer, and id say either this sensor is u/s or the connector/wiring to it is. Without it, the system dosnt read a temperature, so reverts to the maximum glowplug time.

[Hobbz]

It could be a simple wiring problem ... ill have a talk with a friend of mine and get back to you .. Just to make sure, you are using 2 types of plugs right ?

[Woop]

TD42 uses a sensor at just to the right of Thermostat housing to give coolant temp info to the glow plug timer located in the drivers side kick panel. Usually the time they glow for is about 3-4 seconds when cold then they cycle on and off after engine is started for about another 10 seconds.

If the connections at the temp sensor are dirty/faulty the plugs may keep cycling indefinantly after engine is started.

The 2.8 uses a completly different control system.What engine have you got?

Nick

[PJ]

Not sure of values for a 95 model - on my MQ (1980), the sensor blew so I replaced it with a fixed 27K ohm 1/2 watt resistor (MUCH cheaper than replacing the faulty sensor). It means that the variable timing ofthe glow plug replay is fixed, but at least it is being managed. Have a look in the electrical section of your workshop manual. For the MQ sensor an ambient temp of 10deg C normally returns a resistance of 40K ohms, where 80deg C will show around 3K ohms.