Engine temperature guage not registering

[GregB]

Ford Escort 1.8Si R reg. Everything in the heating system seems to work as normal. Fan kicks in as normal when sitting in traffic. The only problem is that the temperature guage is not registering the engine temperature. Can anyone point me to the part I need to replace.
Thanks.

 

[keyplayer]

Could be temp. guage sender unit - located on engine block just below thermostat housing. Usually has a threaded stud that the connector clips over.

 

[GregB]

Thanks for reply. There is also a screw-in type plug unit on top of the thermostat housing - sure it's not that one? Presumably I just unscrew the unit and replace with new - seems difficult to get to though. Also I presume coolant will have to be drained first.

 

[keyplayer]

If I recall correctly, the one on the top on Fords is the fan thermal switch, this should have 2 wires coming out of it. The one you want is single cable.

Presumably I just unscrew the unit and replace with new

Yes, and new one should have new washer. Take care not to overtighten!

Also I presume coolant will have to be drained first.

Strictly speaking yes, but if engine is cold, header tank cap removed and you're quick you may get away with just a small loss of fluid.

 

[GregB]

Both these cables end in two wires at the connection clip.

 

[keyplayer]

Sorry GregB my mistake if it's 2. However its the one in the block you want - if you think about it the guage needle creeps up before the thermostat opens as the engine warms up - the top one is measuring the temp of flow into the rad. Try shorting the terminals on the plug while someone observes guage to see if the needle moves.

 

[GregB]

Similarly, I suppose if I pulled off the top connection and shorted the terminals, the fan should start up!
Thanks for your help.