[niles]

.It depends where your sender is located. Mine is in the water pump housing; thus my guage never showed a high reading.
The boiling occurs in the head/thermostat area and the water expands and a large bubble occurs in that area, you can hear gurgling and boiling sounds in that area.

Check you pressure cap!!! If working right you shouldnt be boiling and punking unless something is serioulsy amiss. You need a pressurized system and a good purging of all air; if you have air trapped anywhere you get those symtoms

gn