thelaibon

Guys: I drove it around town yesterday and indeed 2-3 different times, the temp gauge skyrocketed and DURING that time, the truck was struggling. It shimmied as I stepped on the gas and struggled to maintain 20-30 MPH. It's worth noting that i was able to drive thru it and the proper acceleration/power returned after 2-3 minutes, however, the temp gauge didn't return to normal until at a light, when I turned engine off and back on, it "reset" to the middle area.

I'm afraid that I didn't burp it properly. Can anyone elaborate? Jethat and GT you both provided methods, thanks. any commentary on my method? Didn't seem to work. Exactly what I had done:

parked on homemade vehicle ramps, uphill in driveway
reservoir cap off.
start truck.
turn on heat on max.
tiniest bubbles are seen in reservoir after 5-10 min.
coolant level never drops - it rises to top of reservoir and spills out, say after 30 total minutes.
I cap it and shut off engine.

BareBonesXL

How about a binding water pump? Maybe with a loose or worn belt contributing. Your symptoms seem to fit no or low coolant flow.

BareBonesXL

These words indicate just a funky gauge though. Your subconscious might be feeling engine behavior that's not really there.

thelaibon

Well it definitely was struggling... I had my foot firmly on the gas pedal while temp gauge was skyrocketed, and i was barely able to drive 20-30 MPH, truck was struggling bigtime.

I'm really at a loss, here, very frustrated.

I'm trying to learn how cooling systems really work, how they get air in them, and how to remove it. Problem is, I don't know if my 97 F150 is different from other vehicles in this regard. I don't have a normal radiator cap, or normal radiator entry point, except for the bottle. Is that a degas bottle? Does air purge out of there? If not, then where? I'm really lost.

thelaibon

GT, do u suggest me fully draining my coolant system out and refilling it your way? If I drain it out via the petcock, will that empty everything out, and if not, then how?

BareBonesXL

I know on my 2003 model that there's an overheating engine protection function. The engine control system shuts off half of the cylinders to reduce the heat production. I don't know if they had that in 1997. It's described in the owners' manual. Many engines have this system, my friend's BMW has it also. If that's the case then your engine really is overheating and the engine is struggling because it's running on half power. I just checked a 1997 service manual and 1997 has that feature. So that might explain the engine struggling when it overheats.

When the gauge starts to rise, stop and check the belts and water pump for slippage. Make sure that it's spinning like it should be. The fan is on the same shaft as the water pump.

Don't get all of the odd things that are happening blended together in your head, keep them separated And try to be very detailed in describing what you see. Like, "skyrocket" for what the needle does sounds dramatic but doesn't really tell much, and also implies that the engine got so hot that you probably warped a cylinder head or blew a head gasket. Which is a possibility. If the needle pegged out in a second and stayed there and you tried to drive through it, you might have damaged your engine. You're supposed to stop immediately when the engine overheats.

So you might be in the middle of a very expensive lesson about how engines work. Sorry and good luck. Once a head gasket blows or a cylinder head warps you have to remove the head(s) to fix it properly. Sometimes they'll seal up enough for the egine to run when it's cold but then leak again when the engine gets hot. "Skyrocketing" temperatures is a common sign of either.

To be clear, the head gasket goes when the head warps.

thelaibon

I totally get what you mean. When I say that the temp gauge skyrockets, I mean that one second it's right in the middle and the next second, it's maxed out. And when the episode is done, it returns to normal range. There is no time in between, not even 1 second. This, perhaps, implies that, as you suggested, maybe a gauge or thermostat is faulty, ie anything that would TELL the computer to panic, and would perhaps thus engage the engine protection mode you mentioned, where half the cylinders stop working. So my point is that I don't reckon the truck to ACTUALLY be overheating since I never smell fluid or see smoke/fluid (and you mentioning the engine protection mode helps to explain why the shimmying/loss of power).

In the meantime until this gets solved, I will take your advice & not continue to drive when the gauge maxes out, just in case I'm actually overheating.

BareBonesXL

That seems plausible. A bad sensor causes the protection function and gives the faulty gauge reading. I don't know how Ford drives their temperature gauge. Many cars use separate sensors for the computer and the gauge, but maybe the 97 4.6 uses the same.

The speed that the gauge reacts implies that there's either a short or an open in the sensor circuit, if it's not actual heat at the sensor causing it. You might find that sensor on the engine and check the plug and wiring. Unplug and see if the gauge goes up or down. Or just do some more Googling and find a real test for it. Maybe you'll get lucky and it's just some bad wiring.

white89gt

The temp sensor for your dash gauge does not give feedback to the ECU. If your gauge is going up, AND your truck is running differently in conjunction, then you are indeed getting into overheating range. And my guess is, there is still an air pocket, or you have a slow moving pump.

thelaibon

If that's the case, then how does the ECU find out about the overheating? I'm receiving overheating codes.

PS, I burped the engine again today - same as the method I mentioned a few posts up, except this time I revved the engine at the throttle body at say 2500-3000 RPM after the engine was already warm, with the cap open of course, and I saw MAJOR AIR bubbles coming up. HUGE. For like 10-20 seconds. I repeated the process a few times for good measure, and there were no more bubbles. Sure enough the coolant level sank a good inch or 2, makes sense since air was displaced. Didn't drive yet, will drive extensively later & tomorrow.