Ok..I have a 1999 Ford F-150 4.2L v6 singlecab. I had some overheating problems about 6-7 months back. Brought it to a shop(trustworthy) and was told my waterpump was bad. I had it replaced along with the thermostat and on the way home started overheating again. Brought it back and they said the radiator was full of trash. So I had it replaced. Truck ran fine until about 2 months ago.

I had been driving for a good 40-50 minutes at 65-70mph and the temperature gauge started rising and eventually went all the way to the red line. I stopped let cool...turned around no problems all the way home.

Haven't had any other problems except for driving to austin with my kayak on top and it was really windy and the roads up there are just up and down up and down so i figured it was just the kayak's wind resistance putting a load on my truck. Had to baby all the way home.

Now I try to tow my boat to the lake and my truck wont even make it 20 minutes down the road without overheating. Small boat 19 foot.

Any thoughts would be much appreciated.

Coolants fine.
Top radiator hose is red hot while bottom is luke warm-kinda hot.
just had oil changed
heater hasnt worked for about a year and half

 

Try another thermostat.

 

Could be a collapsing hose or a fan clutch, with the truck off try to spin it

 

Am assuming your 99 has the same radiator and overflow tank set up as my 02, it is very hard to get the system full of coolant, it needs to idle a long time with cap off to purge air from system. Make sure it is full of coolant, and why doesn't the heater work, has it been bypassed?

Overheating at highway speeds is pointing towards radiator unless it is air bound.

 

I took the boat to the river yesterday. It's much closer, about 20 miles. The truck seems fine if I run under 55-60 miles but over that, and the temp will gradually climb and overheat.

The fan spins but not easily when the truck is off. The heater isn't bypassed that I know of. I never seem to see the coolant in the runoff gone. (Like my thermostat isn't opening all the way.

But even if its that it should overheat at low speeds as well huh?

As always, I appreciate the help guys.

 

I have the same problem only my fan is ridiculously loud at times but the ac is off. Also it's a stick so it heats up on a slight uphill but when I put it in neutral downhill it goes down to normal. The engine doesn't seem to be overheating though. Thermostat just changed. I heard it could be a sensor. I've done this type of trip numerous times. I'm going to change the radiator cap to see if that does anything. Advice?

 

have u tried replacing the fan clutch? check the radiator hoses, sometimes they collaps and water wont pass thru them the way it should.. also might wanto look into radiator air bleeding..

 

I'm having the same issue I think. I have a well maintained 99 single cab stepside 4.2 standard trans. A few weeks ago I was driving into work (23 miles) , hopped on the interstate and it seemed like it was taking forever to get up to speed. I looked down and saw my needle was all the way on H. It was my first day at new job and couldn't be late so I continued on, watching my needle like a hawk.. When I got to work I popped my hood and i smelled antifreeze. It was hissing and a small amount was spitting up in the air. The tank was pretty much empty. I bought some water and filled my reservoir on my way home. The whole way home my needle never moved past half like normal. I just drove up to the post office (2 miles) a few minutes ago and when I got home I smelled antifreeze and it was hissing again. My hoses feel normal I guess. What's going on?

Edit: I crawled under my truck and my water pump and hoses seem completely dry but my crank shaft and everything below it are all wet and covered in orange antifreeze. Can a crankshaft seal leak antifreeze and cause overheating?

 

The radiator, coolant pump, and thermostat are new but it still overheats.
1. A defective new thermostat would be very rare but not impossible. I would not suspect that, but the thermostat can be installed backward (I confirmed this on my 4.2). The spring goes toward the engine and I always orient the bleed hole to the top. Keep this in mind.
2. Run the engine until at operating temp then shut it off. Try to spin the engine fan. You should feel strong resistance. If not, replace.
3. Engine at operating temp in park and brakes set, you lay under pass front side and observe the lower radiator hose while a buddy revs the engine to 3000 rpm. If you see hose really collapse, replace it.
4. Fix the no heat condition. You need the heater core to get coolant circulation to purge out air.
5. A leaking head gasket will cause overheating when exhaust gases enter the coolant. This is not very common but happens.

To the guy with the 4.2L coolant leak here is a tip: a steel coolant elbow on top of the engine (pressed into driver side front of intake manifold) often rusts through and sprays from pin hole sized openings. Hard to see because of hoses etc. on top of it. Ford dealer wanted $1600 to replace entire intake manifold. The elbow is about $15 on Amazon (but their picture and title is completely wrong). Search "Motorcraft KM4528"
To replace it, remove the thermostat, break off the rusted tube above the intake, then with a small drift tap the remaining tube into the thermostat opening, remove with magnet. Use blue sealer on the new tube abd tap it in.