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GTS104 thermostat - vented or not?
A post on the V8BB asked whether the thermostat on an RV8 should have a vent. Tthe parts manual lists the thermostat as GTS104 and service repair section of the RV8 Repair Manual AKM7153ENG sets out the procedure for replacing the thermostat. The thermostat is mounted horizontally and a note specifically says "fit the thermostat to the housing with the vent pin in the 12 o'clock position - caution, failure to position the thermostat correctly can lead to air locks and overheating".

Nic Houslip explains in the full version of this note that "the small drilled hole is a bleed hole, primarily to allow a small amount of heated water to go past the thermostat and ensure that the wax bulb gets heated and allow the thermostat to open, it also allows any air trapped which may also prevent the

bulb getting heated. The bobble valve allows a reverse flow of water during cooling down when the thermostat may be closed. You need to check carefully the replacement part has a vent".

The thermostat for the MGBGTV8 is also a GTS104

with the vent in the 12 o'clock position. When you buy a replacement part it's essential you check for the presence of the vent pin and to reject any thermostat supplied that does not have one.

See the full note at RV8NOTE451.
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