I have a 1991 F-150 XLT Lariart with a '93 with a 5 speed manua 4.9L inline 6 in it. i just recently put this new engine in and now when i start the truck the fan automatically comes on and wont turn off, what could be causing this?

 

Don't know what kind of fan/setup you have. But my '98 factory stock setup works the same at startup. I hear the fan spin at startup no matter how cold it is outside. 28 degrees F outside at startup, I hear the fan blowing away, Two blocks later, I stop at a light, I don't hear it. From what I've read here that's the way it's supposed to work.

 

yep fan clutch kicks on to help move heat from outside the engine compartment also nock off any ice on the radiator

 

my fan on my truck stays on for like a mile or two when i first start it...it kills my h.p.

 

What hp? I've driven the inline 6 on and off for 5 years and it's NEVER had get up and go, but it can tow the crap out of anything you put on it. Takes off just as fast with a boat on as it does normally. Mine actually takes off better due to the extra weight on the back. Better traction.

 

i tohught that thats the way its supposed to work. i was told that its should shut off after a mile or so but it doesnt it satys on from wen i start the truck until i shup it off, the fan never stops. why would it be doing this.? also does anybody know why 1990-1994 F-150s have larger tires in front than back

 

your kidding on the tire question, right? Are you talking about the belt driven fan or an electric fan that was added after factory. If the fan clutch stays locked up for more than a couple minutes and the air it is pulling is cold than the fan clutch is in need of replacement. I've never seen a stock ford with a different size tire recommended on the front than the rear posted on the door jam. I think someone was just using up some used tires to save the enviorment

 

ok so how hard is it to take the fan clutch off and replace it. also no the tires atre stock directly from ford. also i have a squeak by the belt housing and it sounds like a squeak or something i am LOST!!!

 

About time to replace them dont you think? Did you own this truck since new? I just have a supremely hard time believing that the truck came from the factory in such an unsafe condition.

 

I owned a 99 jeep Grand cherokee and I replace the fan clutch because it squeeked. easy to change. hardest part will be removing the fan shroud or weazling the fan past it, but I don't think that is that bad.

 

I have owned this truck since it first came out it is directly from ford and i have made no tire mods or anything. the tries in the back are 15 inches and front or 17 inches.? is this supposed to be like that also does anybody know were the 02 sensors are. are they before the first cat or behind it or by the second cat?

 

You must have a "special" truck, I know quite a few people who own from 90 to 96 and all the tires on their trucks matched.....15" from the factory. Do you have a shop manuel for your truck? If not, this may be a good time to buy one, it will explain where all the parts you are asking about is better than any one of us can explain it and it is complete with diagrams and available with the reach of the hand and turn of the page.

 

i know alot about these type of trucks and the questions i ask arent in the shop manaual, thats why ia sk them, anyways yes this truck directly from ford and i kno people who own the same model and year as mine and its the same thing for them,

 

So you've had your truck for 15 years and never rotated the tires???

 

of course i have rotated the tires, only an idiot wouldnt rotate them all i am saying is that they are 2 different sizes and it came driectly from ford