Testing thermostat

[Fab1]

Hi guys,I'm having spark plug fouling issues and suspected my engine is running cold among other things so pulled the thermostat to check it.

Here I have removed the thermostat cover exposing the thermostat still in its housing.

Here I have removed the thermostat from a stone cold engine(Notice the plunger is closed)That's normal.

To test a thermostat correctly it should be suspended by a wire in a pan of cold water and slowly bought to a boil while using a thermometer to note the temperature the plunger begins to open and comparing to manufactures specs.The quick and dirty method is to poor boiling water over it or using hot water from a sink over the thermostat and seeing if the plunger opens.(it should slowly open as you do this and slowly close again as it cools down)indicating its working.

Here as I run hit water over it it is fully open.

Here I have cleaned the thermostat housing and am re-installing the thermostat and cover.

When a thermostat fails the plunger will be stuck open when pulled from a cold engine or won't open when the engine reaches operating temperature.They can also seize partially stuck open/closed also.

Hopefully this easy job will help someone out.

Cheers.

[antonywardle]

Nice write up again. Something like this was happening in a Camry I owned

That was a simple fix