Postby crooky » Fri Oct 29, 2004 5:28 pm
Are you losing coolant? A leaky head gasket will cause bubbling which is visible if you take the radiator cap off. this will be more apparent if you remove the thermostat as the thermostat has a habit of trapping the bubbles somewhat causing localised variations in temperature. When this happens and it is just a small leak, your temp gauge usually reads high whilst the water temp in the radiator can be cold! The temp sender for the temp guage on the dash is just on the head side of the thermostat and the hot water and gas trapped there can send it off the charts. This also can pressurise the whole cooling system and stuff water pumps etc. The boiling jug sound usually happens when you lose water somewhere and the metal not being cooled properly comes into contact with water and instantly boils it.
On the other hand, if you haven't lost much water, it could be a leaky head gasket, building up some pressure and forcing water out somewhere. When you take the radiator cap off, is there much of a pressure release?
When you put the new head in, did you retension the studs after you ran the car at operating temp?
My old T1 developed a small leak in the head gasket after a couple of weeks of running when I put on a new head and gasket.
The water never boiled or anything, but the temp gauge would just keep rising.
This may not be the prob though. Its just a matter of sorting through the possibilities and eliminating them one by one. I'm sure you already know this. Some of the other suggestions (a blockage, timing etc) sounded more feasible for your situation but i guess the more scenarios you have the better heh?
The temp gauge on the T1 I just sould rarely made it past 1/3 of the way once it was running well.
Good luck
Joel