i have 2000 f150 with 5.4 v8. am replacing the coolant thermostat. does the rubber o-ring go under or on top of the new thermostat. In the process of removing the old one i didn't notice where the original o-ring was.

 

I'm not 100% sure but If it takes a gasket and a O-ring I'm guessing the O-ring goes on top of the thermostat. That's only a guess because my 5.7L in my boat has a quark O-ring on top of the thermostat and a gasket between the housing and the block. You may just want to get a Hane's manual to be sure. Post up what you find.

 

Thanks for the info. I did put the o-ring on top of the thermostat and there's no leak.

 

glad to hear

 

A easy home improvement do it yourself project and save up to 30% on your bills by replacing your temperature sensor.

_________________
Thermostat

 

Do we have a smart bottom newbie amongst us? Welcome to the forum anyway.

 

I just swapped a 180 degree into my 4.6L, and it's been quite a while since I changed a t-stat, I was quite surprised to see how they installed the o-ring. I'm used to the "old days" when you had gaskets. I removed the housing and looked for the o-ring on the upper housing and seen none..... then upon looking at the stat, I saw it just laid on top of the stat. Well, I was hopeful that it was something that usually seals OK; but by design, I figured is has to be a pretty reliable method. Probably one of the simplest jobs you can do on a new vehicle.

 

On the subject of Thermostat's, do I need to worry about anything if I'm taking my truck from the heat of Arizona to the colder weather of Indiana? Granted it is summer but I'm thinking ahead to winter. I'm just not sure if I have to worry about anything or not.

Thanks

 

What most people like to forget or insist on thinking otherwise, a t-stat controls minimum engine temperature. 192 degrees is required for the engines computor sensors to function. That should give you all the heat from the heater that is necessary. Admitt, I left Illinois in 1977, 190 was the t-stat of choice back then and long before you were probably born.

 

Thanks for the info. I was born in 67 and grew up in Indiana but then left in 87. Been in either San Diego, Peral Harbor, or Arizona ever since. I'm going to be cold going back. haha