Correct glow plug voltage?

Hi all,

Does anyone know what the correct voltage should be at each glow plug? This is on a 1987 2.5na 12J, with plugs in parrallel.

I'm seeing between 6 and 8 volts depending on which plug. 8 nearest the bulkhead, down to 6 at the front. I'm testing by putting a multimeter across the plug and -ve earth when the glow plugs are energized.

I'd expect a voltage drop, but should it be that much? Don't have an ammeter, so no idea of current draw. Good and charged battery, deliving about 600CCA.

VMTIA
Dobbles

Seems a bit low, run the glows and measure the voltage across the battery terminals.

Assuming your battery is good then the drop at the battery should be small. Could be a dodgy contact. With the glows on I would meter out all the points of the circuit, start before the relay, if the feed is still up nearer 12v then I'd say the relay or a connection to it is the issue.

Thanks.. IIRC the battery dips to about 10v then stabilizes about 12.50.

No relay, this is pre-relay so the current is fed through the ignition switch to the plugs. I should really fit a relay, but need to work out if there's a problem here first.

buggeration.. looks like I'll have to whip them out this weekend to see if they're glowing or not.

Temp down to -8 this morning, and it just wouldn't fire. Ran the battery down in the end. Might have to rig a relay into the circuit sooner than I'd hoped.

How old are the plugs?
They dont last forever.

6V at the plugs in your case will almost certainly be the ignition switch.

I'd get the main feed, do it via a relay and install a push button on the RHS of the column cowling. Feed that button from an ignition switched supply, hit that button it powers the relay, plugs heat and YOU have control over them.

I have this system and I don't use glows in my 90 in the summer or on hot starts - saves the plugs too.

Shifty1962 said:

How old are the plugs?
They dont last forever.

Click to expand...

Plugs are new, just put them in a few weeks ago. I'll have them out at somepoint to see if they really do glow when they're energized, but still on the loom.

discomania said:

I'd get the main feed, do it via a relay and install a push button on the RHS of the column cowling. Feed that button from an ignition switched supply, hit that button it powers the relay, plugs heat and YOU have control over them.

Click to expand...

That's what I was thinking.. shame I didn't get round to it before this cold weather hit. Might wire the relay from the ignition switch, just to keep on the key.

I suppose in the short term, I could just solder a switch onto the glow wires at the ignition switch couldn't i? Then if the ignition is duff, it'll bypass that.

Thanks guys..

Are there some sort of secret super plugs that I don't know about that are so valuable you have to save the use on them?

The ones I put in a few weeks ago cost me £14 for the set and if t hey last anything like the previous set they should last several years.....

Airways said:

Are there some sort of secret super plugs that I don't know about that are so valuable you have to save the use on them?

The ones I put in a few weeks ago cost me £14 for the set and if t hey last anything like the previous set they should last several years.....

Click to expand...

Dunno.. the one's I've got are, Wellman G603, OEM LR I'm told. Cost about £30 for four. I do wonder if Bosch plugs might be better though.