12HT Thermo sensor
- Thread starter sved
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My WAG is that it is a thermo wax device which raises idle when cold out.
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- #3
There is a bimetal vacuum swith 90925-05052 which is doing just that what you describe,so it must be something else it is doing with a certain temperature. Either to hot or to cold ??? Then stop the engine ?? Never heard /read somebody has experienced that phenomena.
What I've been told is that its a device that will shut down fuel supply when the injector pump becomes too hot?
A friend had the wax element not completely return to normal position, so the IP was getting limited flow. It took al long time before we found that one out!!
A friend had the wax element not completely return to normal position, so the IP was getting limited flow. It took al long time before we found that one out!!
This one is thermo element and I suspect it works different to a thermo wax. Is it for cold weather and high altitude as well? Maybe it alters the fuel settings. Its attached to the governor housing
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- #6
You would expect a fuelpump to get hot in warm regions like AUS etc. But the strange thing is that it is not a spec on 12H-T 's overthere.
Only on JAP and EURO engines. It is a COLD SPEC part according to Toyota.
So my quess is it will increase the amount of fuel the colder it gets.
The stop lever is moved clockwise to stop the engine,but the element will move this lever counterclockwise when activated outward.
Time to put it in the freezer and make a little test
Only on JAP and EURO engines. It is a COLD SPEC part according to Toyota.
So my quess is it will increase the amount of fuel the colder it gets.
The stop lever is moved clockwise to stop the engine,but the element will move this lever counterclockwise when activated outward.
Time to put it in the freezer and make a little test
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- #7
Did a freezer test today:
First picture taken at +12 celcius.Measured from end of thread to front of element .
Next picture after 1,5 hours at -20 celcius.
The plunjer has moved inwards aproxm. 1mm.
This means when the temp.drops the stop lever will rotate CCW thus adding more fuel.Only with cold starts,because the engine will ofcourse gradually heat up and so will this thermo element.
When pulling the stop lever CW the engine will stop.This is also a emergency stop lever in case the vacuum shut valve will fail to operate.
Mystery solved so far i quess.So yes this is a COLD SPEC part.
First picture taken at +12 celcius.Measured from end of thread to front of element .
Next picture after 1,5 hours at -20 celcius.
The plunjer has moved inwards aproxm. 1mm.
This means when the temp.drops the stop lever will rotate CCW thus adding more fuel.Only with cold starts,because the engine will ofcourse gradually heat up and so will this thermo element.
When pulling the stop lever CW the engine will stop.This is also a emergency stop lever in case the vacuum shut valve will fail to operate.
Mystery solved so far i quess.So yes this is a COLD SPEC part.
Allright, thats proper testing. But.... what would happen when you warm it up further? 
- Thread starter
- #9
Did that ,
from + 12/15 celsius blasted it with a air heatgun untill i was unable to touch it with my bare fingers and there was no measurable change .
So it only functions in one direction. At least on my 30 year old part
from + 12/15 celsius blasted it with a air heatgun untill i was unable to touch it with my bare fingers and there was no measurable change .
So it only functions in one direction. At least on my 30 year old part
Check, mystery solved!
Need a spray can of butane? Doesn’t it come out cold? Cautiously of course!!
Sved, thank you for helping me out on my thread.
Sved, thank you for helping me out on my thread.
Does anyone know the adjustment spec. of the thermo element? (how far should it be screwed in/out to the lever)
Is it possible/advised to remove the element off the IP, like for example the AU version of the 12HT?
Is it possible/advised to remove the element off the IP, like for example the AU version of the 12HT?
This is interesting, the stop lever acts directly on the control rod (which is controlling the amount of fuel delivered by the pump elements) and the way it is built it can only reduce the amount of diesel pumped. My pump hasn't got that device.
I would guess that that cold spec. device is reducing the amount until the engine has warmed up - so the unexperienced driver doesn't rape the cold engine at, let's say minus 25°C /-13°F . But like Sved tested it, it would actually reduce fuel delivery when warm.
Well, it could be that the cold spec. ip is tuned to a higher fuel delivery for starting and once it has warmed up the thermo element actually reduces that amount for normal driving conditions. I have to check that in my wsm - I recall cold spec. settings for the ip there.
Has anybody yet read wsm information or monitoring on the running engine that all are acting as Sved's one ?
I would guess that that cold spec. device is reducing the amount until the engine has warmed up - so the unexperienced driver doesn't rape the cold engine at, let's say minus 25°C /-13°F . But like Sved tested it, it would actually reduce fuel delivery when warm.
Well, it could be that the cold spec. ip is tuned to a higher fuel delivery for starting and once it has warmed up the thermo element actually reduces that amount for normal driving conditions. I have to check that in my wsm - I recall cold spec. settings for the ip there.
Has anybody yet read wsm information or monitoring on the running engine that all are acting as Sved's one ?
One less thing to think about why its there
