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Old 07-04-2012, 04:27 PM
WYOF150 WYOF150 is offline
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2005 F150XL 4.2 overheat issue

I searched the threads looking around and did not find any that matched my exact situation.
Monday i was driving and sitting at a railroad crossing waiting. My check gauges message popped up and i looked down to see the temp pegged. Motor was running normal, AC was off, and did not smell like it was overheating. So i turned off the motor for about 10 min. Started back up, was in the normal ranges, drove for about 10 miles and it started to creep back up and i ran the heater full blast (got some very good heat coming out) and it was able to keep the temp in the upper normal range. But every once in a while it did skyrocket from like 3/4 position to in the red, did the same thing, stop, cool down and restart.
Each time that i stopped i checked both hoses, both were fine, pressurized, full of fluid and the upper was hot, but not scalding hot. Lower was a bit cooler. I then checked the degas bottle and when i cracked it slowly, got a small amount of pressure out. Nothing too major. Coolant looked fine, was hot but not scalding hot. Upon getting home i parked and the next morning went to change the thermostat which i thought it was that. drained the radiator enough to empty the upper tube to get it off. When i drained it, it flowed great, was bright green, no debris. smelled normal and when i tested it with my tester, tested out perfectly fine. Upper tube was clean, no debris, thermostat came out cleanly, was a bit sticky and was hard to manipulate. When tested with hot water the tstat did open, but slowly and looked like with some strain. And the water outlet was clean and had no buildup whatsoever. The entire cooling system was clean and had no leaks anywhere. My question is, does this just sound like the tstat? I have had alot of people say my water pump was bad or that my radiator was plugged. Just wanting to get an opinion of individuals that have worked with this before. FYI it was flushed last year in early spring. I had to have the parts shipped in due to my remoteness and due to the fact that oReilly only has Murray tstats which don't fit worth a crap. So i figured that if i have to tear into anything else, i should find out now while i have things torn down. Any help would be greatly appreciated.
One other thing is that when i was driving i could maintain a safe but high operating temp, but when i mashed on the throttle in the slightest, it pushed the temp even higher.
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Old 07-04-2012, 04:38 PM
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Papa Tiger Papa Tiger is offline
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In this kind of weather without a water leak the thermostat is sticking, but also check to see if the water pump bearing is loose/wobbly pully with belt off. Let it cool down to room thep though first. LOL
F150's my best friend.
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Old 07-04-2012, 04:58 PM
WYOF150 WYOF150 is offline
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That was my first thought, I took tension off the belt and spun it, no wobble at all. yes i know about letting it cool down. I let the tstat housing contact my arm the other day. OUCH! that thing retains heat. I'm pretty positive about the tstat. But the sad thing is that how all the Murray tstats say they will fit my engine. HAHA. Only the napa one and the mopar one fit. Probably the most frustrating repair i have done so far. tstat and gasket are being overnight-ed fed ex. They are on a plane right now! Kinda sucks living in BFE. Hey, any need to ad rtv to the gasket?
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Old 06-27-2013, 01:00 AM
WYOF150 WYOF150 is offline
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Forgot to update. Installed the oem ford tstat. Gasket leaked slowly for about a month and then stopped seeping. overhead problem solved. Didnt pressure test it. But i have only lost about a quart of coolant in the last 4 months. will end up pressure testing it later this fall.
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Old 06-27-2013, 01:00 AM

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