Have been following instructions on pre-heat times before cranking the engine, yesterday I did not pre-heat and it started with no noticeable difference. The amp gauge barely twitches to the discharge side when the heaters are switched on. Me thinks it is only the solenoid drawing a token amount of juice (can hear it click) and suspect the heaters are not working. Easy enough to verify that voltage is reaching them but after that, is there a way to tell if they are actually getting hot without removing them? D4D with an A330D and what look to be pencil type heaters in pre-chambers, same as a 3304? Worked in an industrial engine machine shop in the early eighties and dealt with my share of twisted off heaters in pre-chambers. Usually the chamber had to be replaced.
Quick check on glowplugs is to use a test light clamp to the battery hot so that the lamp lights when the tip is touching ground disconnect wire touch the probe to glow plug if they are burned open the light wont light and they are obviously bad
If there working you should see about 4 amp draw for each glow plug I think.
Firstly your engine is a 330C series engine if its a 4"3/4 bore unit, the heater plugs can be 1 of 2 styles used but they both draw the same power to work them at 5 amps per plug, 4 x 5= 20 amps, the wiring might well be not correct or not hooked into the amp meter gauge on the correct side to show a discharge reading, the best way to test your heater plugs is to remove them from the engine and hook them up 1 at a time to a battery charger, 12volts setting on the charger is fine also have it on the lowest setting you can, they will glow hot if they are any good, this is just using the croc clamps from the charger to the plug, to test the heater rail use a multi meter set on 24 volt or above (200 is common) DC. tctractors