t4 cooling system problem

[alfiboy]

Hi, Am new to the forum currently in France and having problems with my 2.5 t4 transporter tdi. This problem has been going on for 6 months can't figure it out.It doesn't overheat, it dosen't loose alot of water but the warning light keeps bleeping. When it has cooled down the expansion bottle will have no water in it but when i undue the water cap it fills back up with water. I have bleed the system. Also the heating goes and comes. It is using some oil sometimes but i have no oil in my water or water in the oil. I have started taking it apart and found a little pump in the water system that is electronic does anyone know what it does or can anyone help with my other problems?

[lostboy]

Hi m8 rebleed the system you have all the signs of an airlock "hot n cold heater",the warning light is actuating as the header tank is dropping level,the pump you mention is a circulating afterun pump to stop head warpage and head gasket problems and should actuate on switchoff at a temperature of 217 - 219 degrees F,the best thermostats to fit to avoid airlocks should have a jiggle valve on them,sadly most of the new ones don`t have these,I found drilling a small hole in them avoids airlocks if they have the jiggle valve missing.

hope this helps~~ Jeff