Super Glow giving me super Sh##s

[ausdog]

How many volts is enough volts to trigger the super glow relay? After having to glow a super glow system for at least 30 seconds before starting I thought somthing was amiss. After stuffing round and checking all the glow plugs, relays, resistors and regulators I found nothing wrong and did it all again. I found that while the glow plugs were still getting power the volts were a little low. This was because the super glow realy was not cutting in but the after glow realy was. The super glow relay is getting power from the timer however it is not enought to trigger the switch. When measured with a multimeter the volts start out at around 10 when the ignition is first turned on but slowly drops away to nothing. I have found out that the super glow relay glow duration is controlled by the temperature sensor in the engine block.

Now for the million dollar question, does the temperature sensor trigger a set switch in the glow timer which breaks a circut to the super glow relay instantly or is it a graduated switch which drops voltage slowly depending on temperature? I am trying to figure out if I have a crook temperature sensor or glow timing unit.

Incase you are wondering, the battery in new and maintains at lest 12 volts even while glowing (afterglow), the model is a 1989 surf LN61 with a 2LT motor and the super glow relay still funtions when run directly off the battery.

Now, after spending 4 hours on this one I am off to bed.

Thanks for all who have a go at this one........

[phoebelala]

How many volts is enough volts to trigger the super glow relay? After having to glow a super glow system for at least 30 seconds before starting I thought somthing was amiss. After stuffing round and checking all the glow plugs, relays, resistors and regulators I found nothing wrong and did it all again. I found that while the glow plugs were still getting power the volts were a little low. This was because the super glow realy was not cutting in but the after glow realy was. The super glow relay is getting power from the timer however it is not enought to trigger the switch. When measured with a multimeter the volts start out at around 10 when the ignition is first turned on but slowly drops away to nothing. I have found out that the super glow relay glow duration is controlled by the temperature sensor in the engine block.

Now for the million dollar question, does the temperature sensor trigger a set switch in the glow timer which breaks a circut to the super glow relay instantly or is it a graduated switch which drops voltage slowly depending on temperature? I am trying to figure out if I have a crook temperature sensor or glow timing unit.

Incase you are wondering, the battery in new and maintains at lest 12 volts even while glowing (afterglow), the model is a 1989 surf LN61 with a 2LT motor and the super glow relay still funtions when run directly off the battery.

Now, after spending 4 hours on this one I am off to bed.

Thanks for all who have a go at this one........

Just wondering why you need so much glow in OZ. My truck starts on the key in any temp in England even down to minus 10 degrees. Yes the glow is controlled by a sensor in the block and stays on for a few seconds in really cold weather but this is always enough.

Super glow? I never heard of this m8

Could you expand on this?

Al.

[TonyN]

The EFI 2.4 I have here gets 11 volts till the first relay click (roughly the time the glow light is on), then 8-7 volts till the second click, then 0.



Can't try a non EFI truck till later, Linda's out giving it a test drive.

(I assume 'Super glow' is Oz for the normal preheat with the dash light on )

[ausdog]

The EFI 2.4 I have here gets 11 volts till the first relay click (roughly the time the glow light is on), then 8-7 volts till the second click, then 0.



Can't try a non EFI truck till later, Linda's out giving it a test drive.

(I assume 'Super glow' is Oz for the normal preheat with the dash light on )

Thanks Tony, that is a bit of a help, my glow plugs are only receiving the lower voltage off the second relay, thus the problems with the first relay. Don't worry about giving Linda's car a test by the way. The drop in voltage I was measuring was actually in the initial relay trigger, the smaller wires that come from the timer unit.

In regards to phoebelala's question, most surfs after 2.2 L (2.4 up) have a super glow system compared to the older style "variable delay" preheat system found on most older diesel motors. The older variable delay system provides a constant voltage to the glow plugs which causes them to heat gradually before a timer turns them off, most often regardless of the engine temperature (I think). The super glow system uses two relays and two voltage levels. The initial glow is the highest voltage and only remains on while the light is on on the dashboard. On super glow cars this duration in governed by engine temperature and the timer. The warmer the engine the shorter the glow time. After the initial relay has turned on and off the second relay called the afterglow relay is triggered which maintains the glowplugs at a lower voltage. From what I can gather the benefit of this is that the initial glow voltage is much higher than the glow plugs can sustain for a long period of time causing them to heat more rapidly, then before they start to overheat the afterglow relay triggers and maintains them without the danger of them burning out. This results in a shorter glow time before the car can be started without excessive cranking, smoke and rough idling.

As you noted your car will start almost instantly and the light will stay on longer in cold weather, this is the benefit of the superglow system, however the initial high voltage glow that rapidly heats the glow plugs does not seem to be working in my car meaning that I have to wait much longer before the air temperature around the plugs reaches a high enough level to cause instant clean combustion under pressure when the engine is cranked.

Thanks both phoebelala and Tony for you help.