I have a 1995 f150 4.9l it got really hot this summer so I pulled the termastat. She still runs good but wondering how important the termastat is? Now if I drive a bit the gauge goes between the n and o. With the termastat in I've seen it as high as the a and the l. So should I put it back in? Thanks

 

I would put the thermostat back in after flushing the cooling system. Your engine is designed to run with one and it will run better if it's there. The thermostat makes the engine warm up faster, which makes the heater work in cold weather. Your cooling system probably needs to be flushed. Use a good heavy duty cleaner from any parts store. Also, flush the outside of your radiator with a good strong water hose to wash out any bugs, trash, etc from between the fins. Check the fan belt to make sure it's tight and in good shape.

 

Ok thanks

 

On the termastat it's spring towards the block right....still don't know why the gauge goes so high I replaced the radiator already....

 

Try replacing the fan clutch. Stick your hand in the fan (obviously while the truck is off) and turn it and it turns freely, the fan clutch is worn out.

 

You read my mind just did that clutch is bad I'm still putting thermastat back in.....thanks

 

W/o a thermostat, you will never get more than 10 MPG. Right around 185F, the ECU begin's fuel trim. Below that you are stuck in over rich warm up mode.

 

I think my fan clutch is good the fan spins but stops right away so there is some resistance....

 

Ymeski.....my mpg is really bad about 10 if I'm lucky

 

Now you know why.