over heat question

[swampbuck62]

84 f150 runs great...unless in traffic with AC on then it gets hot fast... as soon as you cut AC off it cools right off..

possible causes?

 

[BIKER13]

coolant? Fan?

 

[swampbuck62]

coolant? Fan?

bet it's been a 100yrs since a good flush.. and will check fan clutch.. the Tstat on this thing is a female dog to get to...

 

[BIKER13]

I have a 1990 F150.6 cyl.auto.

 

[DMGun]

There should be a clutch on the fan that makes the fan "engage" and turn along with the engine more when it senses a higher temperature. Is the fan freewheeling?

WITH THE ENGINE OFF!!! - You should be able to spin it easy when engine is cool, but it should be hard to turn when engine is hot.

 

[Traderjohn]

Could be the water pump is so worn that it doesn't produce ample flow at idle speed.
I've seen this on a toyota. Even without the a/c, this truck would start to overheat at idle speed.
I changed the thermostat to no avail.
I hanged the water pump and she was fixed.

 

[Jimmythedestroyer]

fan clutch/water pump/t-stat.

prob the fan clutch do you ever notice the fan getting louder? if not then its the clutch. let it idle in the drive way with the a/c on and see if the fan speeds up or gets louder if not deff the clutch.

 

[swampbuck62]

There should be a clutch on the fan that makes the fan "engage" and turn along with the engine more when it senses a higher temperature. Is the fan freewheeling?

WITH THE ENGINE OFF!!! - You should be able to spin it easy when engine is cool, but it should be hard to turn when engine is hot.

fan clutch is new or at least appears to be new...

 

[semi-pro]

check timing

 

[swampbuck62]

check timing

timing dead on just checked it last week

gonna start with the easy stuff first a good flush and new t-stat then go from there, this the problem with a drive while you resto project...