As I was driving to work last friday, the temp gauge on my F150 with a 5.4L V8 shot all the way to red, i drove a little while and it never steamed or drove any different. On the way home it overheated again and after driving a mile or two it started running rough. I changed the thermostat and still overheated so i flush it good, checked the water pump, took the radiator out and ran water through it, it has good flow through it and my fan is blowing hard. It only overheats on the highway and turning the key off and on resets it temporarily. It still runs fine and the belt isn't slipping on the water pump. It does build significant pressure on the top water hose and tons of pressure on the overflow jug. CAN ANYONE HELP ME!!

 

Tons of pressure sounds like the dreaded head gasket. Cooling system might be good enough to take it at low speed if it's a minor leak.

You don't want to run it very long if it is a head gasket.


Good Luck,

ford2go

 

If you don't think that it is really overheating, then I would suggest the temperature sending unit. Just a thought... Good luck.

 

I thought about the head gasket, but wouldn't it dis-color the antifreeze and put bubbles in the overflow tank? I'm hoping its something else because this all started happening the day after I put a bottle of Bars Leak in the radiator, it was leaking around the bottom hose.

 

Where exactly do you think the...

...come from?

Its got to be boiling or developing a combustion gas leak bubble.

I presume you're familiar w/Triton's "Fail-Safe Cooling System"?

 

well the overflow tank on my 2001 acts like the radiator top tank on older trucks, IT has a pressurized cap and does have several pounds of pressure after running for 30 minutes. there should not be air bubbles in the tank, and it should not use fluid, but it should have several pounds of pressure inside.

 

I just did a coolent change on my Truck and my Mustang. Both have about the same system. You really have to pay attention and not let any air get trapped in the system. It took me at least a half hour on the Mustang till I got all the "burping" done. It's kinda' messy, but it has to be done to assure that the system to air free. The Mustang was a B%$#$% to do, just when I thought I was done, suddenly the tank would be dry again. I plan to drive it this weekend if it's nice, I went out this AM and I see the tank is about 2" low on coolent. My "long winded" point is... get ALL the air out..

Spotty

 

This makes me think you have a temp sensor/sender problem. If the computer thinks the engine is overheating, it will kick into fail safe and run rough. I'd try changing the sensor before messing with head gaskets.

 

today it overheated again, and now its leaking oil from the passenger side of the motor

 

How do you "burp" it.. i didnt have to do anything special when i changed the coolant in my truck.. but maybe its because i only removed what i could get out of the spout at the bottom of the radiator, and not all the coolant in the block..?

 

You basically let it idle with the heater on high with the windows down. When the thermostat opens you will feel a rush of heat from the heater and the level in the tank or radiator pulls way down real fast. When that happens some air will get sucked in. You then top it off and as it idles it will slightly overflow as air bubbles gets pushed thru the system and out the opening. You keep topping it off until the flow is steady and stable. Put the cap on and shut it down, check the next day or when it is cold, you will need to add a little. The right way is to leave the cap on and open the bleeder(if it has one) which is hooked to a hose and recovery bottle. However you do it, any air trapped in the system will compromise the cooling. Another hi-jack coming.... I see you are in Florida. Our son and 3 friends called Sunday from Orlando (first big road trip), they had been there for a week. Just to leave, car dies. Calls me, sounded like fuel pump. I called a Goodyear place, had it towed in, $1200 later he had a new pump and on his way, made it back to Minnesota. They did a good job, got it fixed right away. My cost on that pump and module, filter, etc is about $300. Not much I could do 1600 miles away. Sometimes you just gotta' pay the man... Hi-Jack over..

 

How does "heater on high" & "a rush of heat" help burp?

There is no hot water valve to open. Antifreeze circulates thru the heater core regardless of whether heat is on or off or whether thermostat is open or closed. The level in the tank "pulls way down real fast" when air trapped in the block gets dumped w/o touching the heat control. The water pump circulates antifreeze thru motor & heater all the time. When the thermostat opens it lets air trapped in block out & allows AF to circulate thru radiator.

 

It doesn't help anything. I simply mention it as a nifty way to know when the thermostat opens and you know you have at least enough coolent added to get stuff moving . Having the windows down simply aids in not making the interior temp get high if you are doing it on a 95*day.