ninjadude11

hi , i have a 98 f150 with a 5.4 , and it isnt heating up like it should the temp reads about quarter , and the rad never gets hot same with the upper rad hose it just gets warm to the touch, this is the third thermostat i have put in it , plus a new fan clutch , rad cap , and the entire system has been flushed and refilled, any one else run into this problem?

torkum

Have you check the performance of the water pump?

Good old Bill

Welcome to the forum and thank you for a strange challenge. Not getting warm? As in all engines the T-stat sets minimum engine temp. Am assuming the rating is 192 degrees. What is causing the coolant not to come up to proper temp? In all my years, this is not normal. Has to be flow or circulation out to the radiator and thus cooling down the coolant. Can believe the gauge acting up or some other instrumentation malfunction, but the top hose only warm to touch. Need more history about the truck. Does this thing have an additional heater core acting as another radiator? Turn off the heater and turn temp dial to cold. Lets stop all air flow across the heater core. Is this a Ford t-stat? And does it have the rubber gasket around the outer flange? Something is allowing coolant to get out of this engine preventing it from getting hot.

NGM

I would make sure that the coolant is full that is the most common cause of no heat. The second most common cause is a thermostat stuck open. Check those and get back to us. Good luck.

ninjadude11

hi guys, thanks for the replys, yes everything is dead on , ive tried three different thermostats, and same problem it just blows luke warm from the heater no heat,took the heater lines off and blew them out no restrictions, no there is no after market cooler, i thought the same thing it must be leaking past the thermostat, but i dont think that is the problem , the manifold does get hot , but the rad upper hose and overflow tank remain cold, one other thing it never seems to build up pressure , i was reading on another site and same problem , turned out to be the water pump wasnt pushing the coolant , so that i think is my next check? ive also checked the blend door and it is working properley, thanks for any info
tim

ninjadude11

well i took the water pump off , and it is fine no broken or loose fins, so i guess i will be squeezing the upper hose and see what happens.

alaskafunboy

Flush out your heater core, and if you take out your water pump, replace it. good luck

Good old Bill

Still no luck, most problems are overheating. Insufficient coolant flow, you state the opposite. You are flowing water all the time and its not in the engine long enough to get hot. Thats basically it. The engine is a heat engine and needs to be cooled to prevent overheating. You are constantly passing water out to the radiator and its being cooled.

ninjadude11

hey thanks for all the replys, found the problem , where the thermostat sits it is all uneven could maybe be from over heating? but i noticed when i put the thermostat in, it would not sit flat . and if you run your finger across it you can feel how uneven it is. so what i did was make a gasket for the bottom of the thermostat, and put a layer of pipe sealant on it let it setup and tighten it down, its not perfect but seems to be working better, when i have time i will take the manifold off and either replace it or try and grind it flat, thanks to every one for the ideas, it was starting to drive me crazy!!
have a merry christmas!