My 2000 F250 5.4L XLT 4x4 170k has an overheating issue. It was gifted to me in this condition, so I do not know if it was a slow onset or a sudden one. The truck will idle all day and not overheat, but it seems once it gets a load on the system, it will have issues. I will be driving and notice the temp from the heater starts to get cool, look in the mirror and see steam trailing my truck and the coolant temp starts climbing. It will pin all the way up in the red for less than a second then drop right back down to normal. At this point, it already boiled over and lost coolant. I've cruised around my small town without issue and other times the coolant boils over. I've driven down the highway at 85mph without issue. The overheating seems erratic and doesn't seem to have any specific cause. I have had the coolant system pressure tested, it passed. I have had the block tested, it passed. I have had the exhaust gases checked, it passed. There are no visible leaks, no loss in coolant (unless it boils over), and no white exhaust smoke. I replaced the coolant cap with a Murray cap and still have the issue. I have a Motorcraft one in the mail just waiting for it to get here. I purchased a Murray water pump and thermostat that I plan on putting in this week. I tried using the search function to see if others have had this problem, but it didn't pull up anything specific.

Other than those things, is there anything else I should be looking for? The 2 weeks I've been driving it around I can hear coolant sloshing/flowing in the heater core regardless of how much coolant is in the system. Could there just be a big air bubble that won't come out? Maybe a clogged coolant system somewhere? I'm really stumped and don't want to throw money away for no reason.

 

If you had the cooling system pressure tested and no leaks, I'm thinking a new thermostat will fix it.

 

That's what I was hoping. I have it, just need to put it in. I'm off tomorrow and plan on doing it then. Thank you!

 

Went through a look problem with a 2006 F350 5.4 RWD. Did a lot of work troubleshooting, even replaced the coolant temperature sensor which is not so easy.

What finally fixed it- a simple coolant replacement. So easy to do a 2006 F350 5.4, might be easy on 2000. You might consider a course of action of draining the coolant, replace with distilled water, run a while, drain and refill with distilled water, run a while, and drain and fill with proper coolant/ water mix. About $50. Might be worth trying, super easy to do. It worked for me.

 

head gaskets. Pressure test but that is more than likely your issue.

 

It passed the block test and coolant pressure test. It's not the head gasket.