glow plugs keep burning out

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What should the voltage at the glowplug be,and does anyone know how to test the glow plug timer.
The car starts once or twice and then the glow plugs burn out.

Glow-plugs

OK, this is an academic stab at this. My diesel ownership is limited, although I do read a lot.

So far as I know glow-plugs use battery/system voltage, which I assume is 12 volts for your vehicle, so that is the answer to your question. However your problem suggests to me that the glow-plugs are getting the correct volts but not switching off once the operating temperature/cycle is reached and subsequently they are burning.

There are two types of system. One fires up the glow-plugs prior to engine starting and switch off after a set period, and once the engine is running and they play no other role. The second one, on modern systems, due to emission control requirements, use the glow-plugs to assist with cold engine start and as required during engine running to maintain a more stable engine temperature.

I suspect your vehicle does not fall into the last category and the glow-plugs merely fire up to assist with cold engine start and then switch off. So my diagnosis of your problem is not voltage related but rather the glow-plugs not switching off after the designated cold engine start cycle and they are glowing whilst the engine is running and subsequently frying themselves - they would get super hot. Hence they work for a couple of days and then they fail.

Is this a recent problem? How many glow-plugs have you used. If this is the fault then I guess whatever sets the glow-plug cycle time and switches them off is unserviceable and needs replacing. If anyone know what that is please tell the man.

.........and there we have it.

Glow plugs burning out

Thanks, someone has by passed timer relay (in car)and fitted a switch one wire to ignition live joined into green/white wire to timer. Turn switch on 12v to plugs turn off still 4.5v to plugs?. Yet no voltage across switch. Despite this switch being there have never used it is there a timer in under bonnet relay/solenoid behind battery?.

No, No, No, they are 7.2 volt

No, No, No, they are 7.2 volt and not 12 volt.

If they have bypassed the relay then there's the problem, 7.2v glowplugs receiving 13 volts.

exactly, they will definitely

exactly, they will definitely be burning out with 12/13 volts being thrown through them, on the fourtrak you get the typical click of the relay turning the plugs on and off for a short period once the engine has fired, it could be that you just need a new heater relay but previous owner may not of realised so bodged a perfectly good system....like alot do.

Full of ideas but no time to do them!!

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