Hello All

Bought a 1990 F-150 Lariat 4x4 LB 157k 5.0l 5spd.......the previous owner keep up with everything, but recently he said that he wasnt getting any or very little heat out ....so I bought it from him on Sat (good price).........he doesnt know a thing about anything mechanical, but nice guy anyhow.

Ok my point is I checked it over on Sat. and preceeded to drive it to Vermont and back home (400mi)....I let her rest about every 60-75 miles....he had recently had the thermosstat and waterpump replaced, he said after that the coolant temp guage stopped working, its wierd because it wont move while driving, but when its off it will read slightly above C, but I did not get crap for heat, I was in a rest area, and was checking the engine here is what I found:

1. The top radiator hose was very hot and hard (new hoses too), almost like the thermostat wasnt opening?

2. the sensor right next to the thermostat goosneck was broke off

3. the lower radiator hose was warm and soft....new hose but didnt feel the spring inside?....dont know if its collapsing?

so i replaced the temp sensor ....and i still get no heat and the guage doesnt work........is there another sensor that controls the heater hose flow?

also gonna check to make sure they didnt put the thermostat in backwards i guess

Thanx in advance,

Eric

 

On an older vehicle they have a valve inline with the heater hose. When you turn the temp **** a cable moves this valve. The lever on the valve can strip out, so it does not open or close. Feel the heater hoses going in to the fire wall. see if one is hot and one is cold. if so it may be this valve. On some vehicles the valve is in the engine compartment and on others its under the dash.

 

The sensor for the temp gauge shoud be a 1 wire sender. If you ground out this sensor the guage should peg. there are more than 1 sensor. they are used by the computer for monitoring the emissions.

 

both heater hoses were hot.....the sensor i replaced was the collant temp sensor, i believe it has conductive gel inside the threads, and when hot enough it conduct and sends a signal, its a 2-wire plug.......i thought that was the problem cause it was broken, but with that top radiator hose hard and very hot, even after i changed the sensor i am not sure now