I am trying to find out why my thermostat wont open, I just replaced it with one and it was running fine for a few months when just yesterday my truck started to over heat so now my question is is what would cause my thermostat to open sometimes and not others.

 

If you replaced it with the right one I would start looking else where for your problem. The Rad Cap for one. If the pressure in the system is not right it will overheat. Clogged rad, old dirty coolent and the fan clutch are a few others.

You should be able to feel the thermostat open just to be sure. Start your truck cold and let it idle until it is warm, at some point you should be able to feel your upper rad hose go from cold to hot then the top of the rad will do the same.

 

well I replaced the fan clutch with e-fans a while back and have had no problem there and I know the thermostat is not opening up because the uper radiator hose becomes very hard like it is filled with air and when i squeeze it it is super hot and I cant force any air to go anywhere(like how you can usually squeeze it and for the fluid back into the resivouir.) Also what is the down side to running the truck without a thermostat

 

Your upper rad hose should be hard when it is warmed up. When your truck is fully warm there should be 15 (I think. It says on your rad cap) pounds of pressure in the system. Is the rad getting hot too. If so I would say your thermostat is opening up.

Running without a thermostat used to be no big deal before cars had computers. Now your computer will see that your truck is not fully warm and make adjustments. I would think it would not run as well and probably get crappy gas milage to boot.

I would replace the rad cap first. It is the cheapest. How old is the coolent? How many miles on the truck? The rad could be clogged inside with rust (That happened on my Mustang. The whole center of the rad was blocked. It ran great until the outside temps warmed up for summer and then it ran hot as hell) or the outside cooling fins could be full of mud or dirt, I don't know what kind of driving you do with it.

 

well I can only assumed that it was flushed when ford replaced the heater core about 5-7 months ago but usually when the upper hose is hot I can squeeze it and actually touch two sides together and watch the fluid go back into the reservoir but the last time it was almost solid to the touch and I could barley squeeze it any much less make it touch it self but I think I am gonna flush it out a couple of times to make sure it is clean. I know that the fins have some grass in there but noth so much as to completely effect the cooling also does anyone know where I can get a performance thermostat(the one I have opens at about 190f) and on average the temperature where I live is hitting about 95f-105f a week

 

Unless you asked them to flush the coolent they most likely did not. They probably just put the old stuff right back in unless it says otherwise on your bill. It is also possible you have an airlock in the system.

Any speed shop will have a higher quality thermostat. The only real difference between them and the standard thermostats is that they are slightly more accurate to the temp they are set to open at. Bring your wallet they are way more money. I would stick with the stock temp or you may **** off your computer. I have never had a brand new thermostat not work and I have done a bunch of them. I guess anything is possible.

 

sorry for the stupid questions but what is an airlock and if it is bad how do I get rid of it.

 

Only true way of knowing if the t-stat is opening is to remove it and place it in a pan of water.

Get a thermostat for cooking and place it in the water and see if the t-stat opens at the correct temp.

 

Whenever you drain coolant from the system you need to run the truck (with heater temp turned to full hot and the rad cap off) until the thermostat opens so you can burp any air out of the system that may be trapped in the motor or heater core and lines. Top up as needed. If air gets trapped in the system it inhibits the flow of coolant. Since you said Ford did the heater core and then you did the thermostat, that gives you two opportunities to get air trapped in the system. I had my coolant flushed by the dealer and so far so good. With some cars it is easier to do this with the front end raised etc. You should try a search and see what the proper technique is for burping the air out on these trucks or one of the guys here might chime in with it.

You can check to see if your thermostat is opening by heating it but you should be able to feel the upper rad hose then the rad get hot when it pops open.

Again how many miles are on your truck? If the coolant has been neglected you could very well have rad problems.

This is the order I would go after your problem:

Make sure your t-stat is opening up by feel. If it is make sure there is no air in the system. Replace the rad cap (they do not last the life of the truck). Change coolant if dirty or has not been changed before. Make sure your E-fans are working and coming on when they should. Get your rad checked out.

 

i put new coolant with water, in my ford truck, 352
it started a thumping sound when running
i shut it off, it kept thumping,

trapped? bad water pump, ? it was weird,

thanks

 

Thumping is either a stuck thermostat or an airlock.

 

Best way to burp this truck is to pull the heater hose off the top front of the intake. Can't miss it. The goal when burping something is to do it at the highest point in the system. Also as already mentioned, the best way to check the thermostat is to put it in a pot of water with a kitchen thermometer to watch what happens. Also remember when you do that, the temp on a stat is the full open temp. They are progressive in nature and slowly start to open so that it's full open at the rated temp. Your's should me 195 I think.

DO NOT INSTALL A COOLER THERMOSTAT. This temp is where your motor was designed to run and also as mentioned, can ruin gas mileage and performance. Colder stats don't usually fix overheat problems anyways, unless the stat IS the problem of course.

 

Truck threw the code that the thermostat wasn't opening.
I had the thermostat replaced and the radiator replaced (due to a small leak)
The code came back on three days later. Truck doesn't seem to be getting hot according the gauge. Help?

 

If the heater blows hot air, it's probably a bad CHT sensor. If it doesn't blow hot air, the new t-stat is probably stuck open or it's opening too soon.