bj73 thermostat problem

[tommybj73]

hey guys,this is my first post here.

im having a problem with my new thermostat in my bj73 cruiser

it doesn't seem to be opening and will start heading towards overheating,i have never let it go above 95 degrees on my test drives .....here is the run down

the thermostat is a genuine toyota 82 degree with new o ring
it is installed spring down in the housing
i have bled the system
i have checked the thermostat and it is opening at 83 degrees
i have installed the bleed hole at the 12 o clock position
when i remove the thermostat the cooling system works fine but obviously it doesn't reach operating temperature
it has not been overheated
the head is sweet
i temperature gauge is working fine and i also have a very reliable aftermarket gauge

i keep thinking it must be a air lock or that i have put the thermostat upside down

any advice would be greatly appreciated

cheers

tommy

 

[tommybj73]

also it has a new radiator cap and has just had a coolant flush

 

[sadam_husain]

just been through a similar problem when I put a lower temp thermostat in the engine in my fj75, I went through pretty much the same process you have outlined, I thought the new thermostat was faulty but it tested fine in a pot of hot water on the stove and was opening much earlier than the old one I'd removed, turned out I had an airlock in the block and had to bleed the coolant back through system, it runs sweet now but maybe a little too cool so may have to go back to the old thermostat to keep the engine up to proper operating temperature

 

[tommybj73]

cheers mate,i was thinking it must be a air lock as it works fine with the thermostat out....i might drill a larger hole in the stat and try and get the air out