Engine Temperature Question

[Thomas61]

Hi,
Gary Allport's thread has got me thinking about suspect temperature gauges/sensors. Could you fit a radiator cap with a thermometer, would this give you a accurate'ish engine temperature to check against the suspected faulty gauge/sensor. Or is the engine temperature determined in a different way ?
Excuse my lack of knowledge and thanks in advance for helping me learn.

Picture is just so you can see what I am on about not sure if one is available or suitable for our trucks.
8560

[panelbeater]

my brother has put one on his pj,looks good and usefull.he has twin kenlow fans with separate ajusterable thermostats,he likes to know whats going on with his temp as had lots of probs till he sorted it out.all fine now towing in the dales.

[Thomas61]

Cheers mate, Useful to know.
Could be reassuring then to have something not connected to the vehicles gauge/sensor system if you needed or wanted to keep an eye on the temp with actual figures.

[macabethiel]

The pressure caps with fitted gauge would be okay on older cooling systems with no header tank but not sure about later closed header tank systems.

Header tank fitment would not be suitable as the temperature sender would not be sitting in liquid.

To fit the cap on the top of the radiator where a fixed cap is usually fitted might have issues when replacing a sealed cap with one that would open with pressure thus bypassing the header tank system.

Would the cap let air back into the system as the radiator cools down being designed to hold pressure not vacuum?

Just asking ?

[Thomas61]

The pressure caps with fitted gauge would be okay on older cooling systems with no header tank but not sure about later closed header tank systems.

Header tank fitment would not be suitable as the temperature sender would not be sitting in liquid.

To fit the cap on the top of the radiator where a fixed cap is usually fitted might have issues when replacing a sealed cap with one that would open with pressure thus bypassing the header tank system.

Would the cap let air back into the system as the radiator cools down being designed to hold pressure not vacuum?

Just asking ?

Hi,
I see what you are saying about a different systems, I had not really thought/unsure about how they actually work.
I have not really had time for a proper look at what is out there to buy.i was thinking along the lines of the same cap that is all ready fitted on a Terrano radiator but one with a temperature gauge.
All purely hypothetical, another thread just got my brain ticking.

Cheers