I have a problem with my son's 93 f150. It keeps overheating. Here is quick background.

-- changed water pump about 4 months ago ( it was leaking)
-- flushed system, replaced thermostat, belt, idler pulley (bearings were going bad and making clicking noise) and upper radiator hose this past weekend. Filled with new 50-50 Prestone.

Still it is overheating. The fan is turning fine. Not sure how to test if the fan clutch is good or not. Maybe someone can help me out on that as well. I also read on another forum that the a/c compressor can be low on freon causing the engine to work harder. Is this a possibility as well? My son says the a/c seems to not be as cold as it has been, but it has also been 100+ degrees here the last few days. Water seems to be flowing through the radiator and engine just fine. With the upper and lower radiator hoses off, i put a water hose in the radiator inlet and clear water immediately runs out the outlet.

I can say that the overflow reservoir is bubbling out fluid from one of the corners of the tank when it gets hot. Is this supposed to be a sealed unit? If so, could one of the corners not being sealed properly cause this?

I would really appreciate any help you can give me to help me fix this and not just start changing a fan clutch. overflow reservoir, a/c compressor and radiator just because that is all I know to do next. Thanks a ton in advance!!! I really appreciate it!

 

With a cold engine, the radiator full, a removed radiator cap, and idling, does it bubble looking down in? After a few minutes of idling and warming up the thermostat to opening, does it bubble then?

Adrianspeeder

 

I know where you are going. I dont think the head gasket is blown but will perform this test tomorrow on my day off to double check. Also, since it is about time to change the oil anyway, if the head gasket is blown would I see anti-freeze in the drain pan after draining the oil? I am also going to go ahead and change the radiator cap and use some plastic weld to fully seal the recovery tank lid.

Thanks for the reply.

P.S. I just retired from the AF about a year ago. I done a 365 day remote to Iraq (Aug 07-Aug08). I was flightline hydro tech but worked KC-135s, B-52s and C-130s. I start next Tues as a civilian crew chief for the C-130s here at Little Rock AFB.

 

That is cool for sure. I'm almost full qual hydro on the 17's because most of the time we are maytag repair men. A 4000psi, titanium lines, fully MS fittinged, with 60gpm electric aux pumps, all controlled by two computers is super simple to work. Only downside is I've been told that hydro troops that start on 17s are waaaay behind the powercurve on any other airframe. When I worked 5's, if it was leakin' thats how we knew there was still fluid in the systems, on 17's any leak is a bad day.

The recovery tank on these trucks isn't pressurized so if it ain't leakin, that isn't the problem.

Adrianspeeder

 

Congrats on the retirement, I take it you will be working over by the base fire department?

1. Is the timing set properly?
2. Install a new 13 psi cap, is the correct temp t-stat installed?
3. Have you cleaned the radiator fins on the exterior, flush back to front with a water hose and Frost King AC Coil cleaner from Walmart?
4. Start the truck and run to operating temp, shut down, spin the mechanical fan blade, does it barely move or does it spin freely?
5. With vehicle cool and off, remove the rad cap, squeeze the upper rad hose slowly, three - five times to ensure no air bubbles are in the cooling system.


James

 

Thanks for help guys. My computer crashed so I have been slow getting back on. Using a different pc now. Anyway, I went ahead and sealed the recovery tank lid and installed a new radiator cap. i done this before reading your reply.
To answer the thermostat question, yes. I went with the OE 192 degree Failsafe model. I also did use a sprayer and wash the radiator fins from the inside toward the outside. I also squeezed the hose several times. I did spin the blades by hand and they would spin less than a quarter turn and stop. No free-spinning. I done all this prior to reading your reply so I haven't checked the timing. Although I assume it is good. It starts perfect, runs smooth and basically purrs like a kitten. Well, the a/c compressor has a small clicking noise, but the engine sounds like new.
I ran it in the driveway and let is idle for about 15 minutes. It never came close to getting hot. So I let my son take it and he went about 15 miles in the city and it started to get hot (3/4 on gauge), so he pulled into video store and let it cool down and then back home.

One question. I wasnt even thinking about it when we changed the water pump but maybe.....is it possible to install the fan on backwards or will it only install one way. We werent thinking about it at the time. We were cold and it was getting late so we were tired. However, if it is possible then maybe that is it. I dont think so because I tore a piece of paper towel and held it in front of the radiator while it was running and it seemed to be sucking it toward the radiator and blowing it away from it.

So what now?

Thanks guys.

 

Wait, what engine is this? '94+ 302's have different water pumps than '93 and older, so if you have the wrong water pump, that could explain it as well.

Adrianspeeder

 

It is a '93 with 4.9L. It should be the right water pump. When we changed it Autozone sold us what the computer said was the right one, but it would not fit so we took it back and they couldnt find out why it wouldnt fit. We then when to O'Reilly's and they had the same pump. Then a supervisor said to look at a reman '92 pump. Since we had the old one with us, we compared the two and they were perfect matches.

 

It sounds to me as though you have a restriction somewhere. Most likley the radiator is restricted. You will not be able to see it and even if it seems to flow water through it when you stick a hose in it, it may not be flowing but through a small portion of the radiator thus not getting properly cooled. I would start with replacing the radiator and cap and also go get yourself a factory thermostat and a new wp not a reman. I have been seeing way to many issue with aftermarket thermostats over the last few years they are not opening at the correct temps or stay partially open or closed. If a factory thermostats is not an option look for a Stant or gates no others.

 

Aight cool. Should be good to go, the only possible error there would be a carb vs. EFI setup which changed in '87.

Adrianspeeder

 

I was also thinking radiator restriction (internal blockage) could be an issue. I prefer a Murray Fail-safe thermostat on my vehicles, when available. And yes, always go with an all new, lifetime warranty water pump.

 

Come on guys, its a 20 year old truck, we know its had problems leaking coolant in the past! When the coolant leeks calcium is deposited in the radiator! replace it and happy motoring.

 

I tend not to just throw money at replacing a radiator if I have the time to run it over to a local shop who pops the sides off, and rods it out.

Adrianspeeder

 

As cheap as new radiators are now that is a waste of time and money in my book.

In fact we no longer have radiator shops in our area that do that any longer and most have converted over to simply replacing them as well.

 

Sorry guys, internet and computer problems.

Anyway, the only prior "leak" problems we have had is the water pump. It actually wasn't leaking but was running alittle on the "high" side then. It wasnt until we were taking it out and "wiggled" it that we noticed a slight leak from the bearings.

Anyway, the thermostat we installed is an OEM "Failsafe" brand. Recently we have went ahead and replaced the fan clutch because it seemed to be only getting really hot after exiting the highway. Now, we have troubleshot closer and it seems to run fine until you turn the A/C on. At that point the temp slowly rises until it reaches 3/4 on the gauge. Turn the A/C off and it slowly drops back down to 1/2 on the gauge. The a/c compressor does seem to make a slight high pitch noise when it is engaged. Could this all be something as minor as the compressor being low on oil or refrigerant? Or maybe the blower motor wheel being VERY dirty. It does seem to have a very reduced air flow rate out of the vents. It is moderately cold, but not as cold as it should be.

Thx.