Hey guys got a bit of a prob. with my 6 cyl EL and I hope someone might be able to shed some light on it... anyway its done about 149,500 km and has been drinking coolant for a while now.
It had been eating coolant at a slow and steady rate (about 200 ml a week or so) up until I replaced the radiator surge tank cap. But now its gotten much worse and I am basically having to bring the surge tank back up to halfway after every drive. Both caps are completely identical in both specification and brand. The old cap was quite loose and the new one is a fair bit tigher to screw down. The coolant disappearing isn't the only problem - its also idling somewhat rough though the tacho says its idling around where it should be for both D and N respectively. Coolant eating aside, I forgot to mention that whenver I remove the surge tank cap now, there's quite a lot of air pressure in the tank - it's like opening a soft drink bottle. And there's a bit of gunk in the surge tank too, looks like dirt floating in it. Also, no emulsified oil/water in either coolant or sump.
Early this year I had the water pump, thermostat housing, thermostat, upper and lower hoses, and coolant replaced by my mechanic. This wasn't too much of a prob. because I could actually see where the coolant was squirting out into the engine bay. The current problem worries me because I can't see/smell the coolant whereas when it used to leak before the pump was changed you could smell the coolant burning in the engine bay. Couple that with the rough idle and I'm beginning to feel my wallet glowing. I purposely put about a grand away in case the head gasket shat itself and I am hoping there is some other explanation for these problems. Anyone able to help?