TR6 Which thermostat TR6?

[Bruce100]

Hi all,

My 72 TR6 runs cold. Am going to replace thermostat. I've read a variety of threads that recommend failsafe thermostats, or thermostats with holes in them to prevent air bubbles. M*ss has failsafe and OEM. thoughts?

 

[poolboy]

The standard T-stat is the 180. It should open within a few minutes of running and remain open as long as the engine is running maintaining the Normal Operating Temperature (NOT).
Failsafe T-stats' selling point is that should the T-stat fail, some of the coolant will still be able pass thru into the radiator. Some are designed to "fail" in the open position, others have a bypass hole, but it seems both may be called 'fail safe' by some.
What you are talking about with the air bubbles is an air pocket, still in the engine, because the coolant was not allowed to burp after a complete drain and refill.
If you do that procedure, refilling without replacing the T-stat until the system is full and circulating normally, then replace the T-Stat you won't have an air pocket..but you still may want a fail safe in case the T-stat itself decides to fail.
A cold reading on your gauge is not a symptom of an air pocket, however.

 

[Bruce100]

Thanks Poolboy. I put a failsafe 180 in - designed to fail open. PO had removed the thermostat altogether, that is why it ran cold. Runs great now. Do I remember a thread somewhere where someone was just drilling a hole in a thermosat to avoid burping?

 

[tdskip]

Thanks Poolboy. I put a failsafe 180 in - designed to fail open. PO had removed the thermostat altogether, that is why it ran cold. Runs great now. Do I remember a thread somewhere where someone was just drilling a hole in a thermosat to avoid burping?

Hi Bruce - air in the TR6 cooling systems is generally not an issue. I'd not start modifying until there is a known issue of known to be good parts.