air bubble?

[swynx]

97 sohc, replaced the thermostat housing, thermostat, both sensors, all the hoses are new. both hoses coming from the fire wall are hot, lower and upper hose are hot. radiator is actually not that hot, i can set my hand on the radiator longer than i can the hoses. temp guage wont come off cold, i have grounded the wire, the guage spikes hot. driving thru town about 30 mins for work, guage stays cold, i never turn the fans on, it doesnt over heat. i got the guage to come up about 1/4 way once, and i was railing it in 2nd gear in the snow for like a minute.

i seem to remember that these sohc engines typically get a air bubble when you fill them. and what i always did at the dealership (forgot this time) was to fill the engine before i put the thermostat in,

 

[RonD]

If upper rad hose gets warm/hot then there is no air at temp devices on thermostat housing

There are two different kinds of temp detecting devices
12volt Sender for the dash board gauge
5volt Sensor for the computer

They are not interchangeable of course

But plugs are often the same

When I go to parts store and ask for a SENDER, I will be given a sensor first time every time, sensor will have a cone shaped tip
Sender will have a cylinder shaped tip


If gauge goes up when its wire is grounded then either Sender is bad or its ground wire is, 4.0l SOHC has plastic housing so sender needs a ground wire
If you pull off its connector and put in a jumper wire, then turn on the key you should get the same high temp reading as grounding the one wire
If so then sender is bad

 

[swynx]

i did add a ground wire, to a local piece of steel. later realized it was attached to aluminum, wasnt sure if that mattered. so i extended it to the fire wall. it made no difference. ive been wondering if the connection inside the plug itself is bad. the 2 sensor and sender have different plugs.

 

[RonD]

You will need to drain some coolant and pull it out, its a pretty simple setup, if wire and gauge work replace sender