thanks sa mga inputs sir, we've done everything as what dieseldude posted pero sabi ng mechanic the aluminum has eaten the glowplugs thread kaya ang natanggal lang is yung outer thread ng glowplug hindi pa rin sumama ung buo. So we replaced the 3 remaining plugs and leave the stuck one as is. Wala naman daw singaw. Nag-improve naman ang starting somehow, 2 clicks na lang pero I think pwersado ang starter because medyo mahaba ang redondo bago magstart. Nanghihinayang ang mechanic to remove the cylinder just to remove the plug...wait na lng daw ako if the time comes to overhaul...