92 f150 302 5 spd 155,000mi
have owned the truck since 40,000mi. the temp gauge has always run steady in one place somewhere between the cold line to the n on normal. all of a sudden its takes spells and moves rapidly between the cold line and n. you can visually watch it move over 1/8in up and down in just a few seconds. i guess the only good thing is it dosent seem to be overheating. speed and rpm dont seem to make a difference. im wondering about the temp sending unit. just dosent seem like a cooling problem. what do yall think?
within the last year i have replaced:
195 thermostat
engine coolant temp sensor
radiator flushed

 

Hi grousehunter,
I had the same problem on my '94 F-150, 302. Here is some info:
1. on EEC engines there are 2 independent water temp sensors installed.
2. the one feeding the EEC is found above the thermostat housing (horizontal) and has 2 pins.
3. the one feeding the gauge (standing vertical with only 1 threaded pin) is hard to find between the intake manifold and the driver side valve cover.
4. to check the gauge, connect the gauge lead (has only 1 pin) over 10 ohms to ground. The gauge pointer should move to Max (H).

I followed this procedure and found my temp gauge okay, so I replaced the sensor. Now the pointer stays normally on the "o" of "Normal".
LoL Dieter

 

thanks german guy.
i changed the temp sensor this evening and the jumping up and down stopped. but now it runs in between r and m on "normal". go figure have personally driven the truck from 40,000mi to now and have never had it run this high before. i am going to change the thermostat tomorrow even though its less than a year old just to be sure.
thanks
grousehunter

 

flush a fill the system