98 F150 4.6L - Overheating...
 

Recently I've had a problem with my truck overheating... Typically it's the thermostat... Prior to replacing the thermostat, I took the truck into a quick lube place and had the coolant system flushed... They flushed it a number of times to clean the system.
I then replace the thermostat with a Stant thermostat... It was rated at 195 Deg.... (That was SPEC.) I noticed that when the truck heats up.... It gets to a point and the gage goes to HOT... Really HOT... and stays there for about 15-30 seconds... and then goes to normal.... And it stays normal.... Has anyone else run into thise type of problem...?
Could it be that the theromatat needs to be one that is rated 190-195...? Lower..? Something that opens at a lower temp... sooner...?
Any suggestions would be appreciated... Thanks..

You missed on the forum, this should be in the '97-'03 F150 forum, but welcome to FTE anyway. Make sure you look around and read the various posting guidelines and user agreements and such. They like to see posts in the proper forums around here both so that your question gets answered by the right people, and so they don't have to move it. They will move this one soon enough, though.

That sounds like it could be: 1) A sticky thermostat; new ones don't always work, I've heard the failure rate of new ones to be pretty high. 2) You could have low coolant still, due to air in the system. Start cold and run it for a few minutes with your heater on full hot (and 'floor' or 'vent' setting, not defrost--that runs the A/C), with the radiator cap off. If you rev it, it should suck the coolant out of sight in the radiator, and burp some out when the revs come down. If it doesn't, add some. Then check your overflow bottle and make sure it's at the right level.

Jason

Jason, Thanks for the reply..... I've tried 3 different thermostats now... I finally ended up using the Stant thermostat... I was told they are one of the best available... Getting pretty good at changing it... I'll try burping the air out of the system... This model doesn't have a radiator cap... Just an overflow bottle.. In the manual it says it acts to purge the system of air as it circulates...
Sorry about putting it in the wrong forum.... Any other suggestions are appreciated... Thanks John

No cap? Shows what I know about the 4.6L engine! My '90 F150 always had some swing in the temp gauge, where it would go up to about 'A' in 'NORMAL' and then settle down to about the 'O' once the truck was warmed up.

Jason

Moved - awaiting merger...

It could be the sending unit is bad. sounds that way to me. or a corred wire at the sending unit. If it gets so hot the question is is it really that hot or just getting improper reads. If you have access to a engine thermometer use it and see what the actual temp is. I would deffanitly look at the sending unit. It should be around where the thermastat is.

Lance