Glow plugs Question

[joemc20]

!.9D DW8, 2002

Just removed old glow plugs which were burned out, and replaced with a new set. used my mutlimeter to determine this and a seperate battery test.

I was having cold starting problems for a few weeks and got worse to a point where cold starting was impossible.
after replacing with a new set it starts good again so i decided to test the voltage and to see when it cuts out,, full 12 volts and about 40 seconds later it cut out. but while i left engine running idle 2 minutes later 12 volts cut back in and stayed there for 4 minutes till i stopped the engine...
my question is this,,, 1, is this normal and 2, if its not normal would it have burned out my old glow plugs,, should i consider an internal push switch where i can control the preheating or just leave it alone,,, tnx from ireland,,,joe

[joemc20]

just tested my berlingo again and it looks like the glow plugs come back on after 2 minutes and stays on on the time,,, is it normal

[Mike]

I've only ever had it where they come on for a fraction of a second and then go off, and they only do that when it is very cold.

[brodfather11]

No its not normal, and yes it will eventually burn out the plugs. If cold they should come on when starting , and go off after running for a little while. (Post and Pre heating ). There is a relay that controls it somewhere under the battery (I think) which is controlled by the temp sensor which decides if the heating and post heating is necessary and for how long.

[joemc20]

tnx guys,, any idea where the temp sensor is located so i can test it.

[brodfather11]

the sensor is fitted on the thermostat casing and has a green connector