So I have experienced overheating and coolant "spilling" when I let her idle for 20 or 30 or 45 minutes.. I smelled it last time and immediately looked under the vehicle and coolant was exiting the vehicle in a steady stream around the transmission/oil pan. I bolted and everything went back to normal.

It has a new thermostat, temp sensor, brand new radiator and water pump, heater core, new belt... The only thing left would be the.. Fan clutch? It doesn't have much free spin at all, and when I showed it to someone at work he said he thought they should have more resistance.. I can only make it spin like 1/4 turn. So I don't think its the clutch.

Shouldn't I be able to idle all day? Or is that common with older vehicles? I've even contemplated converting to a 2-speed electric fan.

I hope someone helps me solve the mystery leak that only occurs because of overheating when idling too long.

Check the sig for specs.

 

You are correct, you can idle an engine all day long without overheating if cooling system is working correctly, if AC is on it will run warmer because AC condenser is in front of the rad and it gets quite hot, but still shouldn't over heat.

Overheating at idle would be a fan clutch issue, assuming you have a fan shroud and radiator fins are clean, good air flow.
Common sign of a fan clutch failing is when you come to a stop, like at a stop light, you will see the temp gauge rising a bit, then when you are moving again the temp drops back down to "normal", fan is not providing enough air flow when stopped, vehicle moving restores the air flow.
This can also be caused by eaten away impeller blades on the water pump, this is caused by electrolysis in the cooling system, when coolant gets too old, not seen too often any more but worth mentioning.

This part: "coolant was exiting the vehicle in a steady stream around the transmission/oil pan", doesn't make sense through, that reads like a core plug(freeze plug) leaking, or a heater hose with a leak that is spraying on to the engine/trans.

As an engine heats up the coolant expands in volume, the rad cap has a pressure rating of approx. 14psi, when coolant expands and pressure gets to 15psi rad cap opens and allows some coolant to flow into overflow tank(expansion tank) then closes when pressure is at 14psi, this is normal and happens every time you drive the truck more than 15 minutes.
When engine is shut off and coolant cools down it shrinks, when it gets to -1psi the smaller valve in the rad cap opens and coolant is sucked back out of overflow tank into the rad.

If rad cap is bad or coolant gets above 260 degrees(normal temp is 200deg) the coolant can "boil", this causes very high pressure instantly and coolant fills up overflow tank and leaks out the top, which would leak down toward the front of the truck, not near trans or oil pan.


Electric fan is a good upgrade for any vehicle, more horsepower for the wheels, better MPG, not noticeable but not nothing either.

 

I just bought a new fan clutch at autozone for 60 bucks. I'll replace the old one and see how much resistance it has when I spin it. I will update this thread again soon and if I ever have this issue again I will post here again. Thanks Ron Dean.

 

So when my dad bought the truck he replaced the whole fan assembly and clutch and all that and the thermostat and idk what else but the clutch is good. What else is there to a cooling system? Nothing right?? My dad tried to say some cars run better when they have less coolant than the factory marked fill line. Also said we could replace the cap and clean the radiator of debris. But I'm not buying that it will solve my dilemma. I'm returning the new clutch and we are going to let it idle until it leaks to find out at least where it leaks from when it gets hot. Hopefully we will get more clues to the getting warm issue. I don't think I've ever let it overheat maybe I know it's run a little warm or hot but I have faith in Jesus christ

 

The fan clutch has fluid and a valve inside, and a bi-metal spring on the front.

When you first start a cold engine you should hear the fan as the fluid inside the fan clutch is cold and valve is closed.
The fan noise should change, go away, within 10-20 seconds as the fluid warms up and the valve opens.
Fan clutch is disengaged now.

Fan clutch won't start to engage until engine warms up, 8 to 10 minutes, and then thermostat opens and radiator starts to heat up.
The fan clutch spring on the front is heated by the radiator, because it is bi-metal(two different kinds of metal) it will unwind when heated and tighten when cooled, or visa versa, depends on the metal used.
But in any case then heat of the radiator changes the spring and closes the valve in the clutch cause the fan to spin closer to pulley speed.
The warmer it gets the closer to pulley speed it gets, and of course, the more air it pulls thru radiator.

So to test fan clutch, you need to start cold engine and run it for 1 minute, then turn it off.
Spin the fan, it should spin fairly freely, usuall a full turn with a good push or pull.

Start engine and drive somewhere, so radiator gets warmed up, then turn off engine and test fan again, should not spin at all, it should stop the moment you let go of blade.

 

How long ago was the fan clutch changed, "when he bought it is unkown to us".
And there is no "it's new so must be good" anymore.
New used to mean "tested and working"
New now means "you're the first to try it, let us know if it works"
i.e. they slap a warranty on it and YOU are now the Quality Control Department(unpaid too, lol)


No car runs better with less coolant, you can not overfill a cooling system.
You can fill the overflow tank to the top and all that will happens is that you will waste coolant, when rad cap sends extra coolant to the overflow tank it will force some out the top so you just wasted that coolant.

The COLD and WARM(HOT) lines on the overflow tank are there so YOU can keep track of cooling system and if there are any leaks
You top up the rad(full, overflowing even) and then fill the overflow tank to the COLD line when engine is cold.

You then drive it normally for the day, then the next morning when engine is cold again check the overflow tank.
If coolant level is below the COLD line then you have a leak.


Yes flushing out the radiator is a good idea, although you really need to remove it to do right, but flushing in place can clean out some debris.
Yes a new rad cap is not expensive and should be changed when you change thermostat or radiator.

 

I have had the truck a little over a year and it does have all new cooling equipment under the hood. I'm flabbergasted.

 

As said "new" no longer means "it works".

Test "new" fan clutch

Outside of low air flow past/thru radiator, heating up at idle would be lack of circulation.
After engine and radiator are warmed up, shut off engine, remove top bolts on fan shroud and slide it back out of the way.
Run your hand across and down the radiator fins, you are feeling for cold spots, there should be a nice even heat across and down, cooler spot indicates clogged tubes.

These can't be "flushed" out, in the old days rads could be unsoldered and the tubes cleaned, that is not possible any more, plastic tanks, clogged tubes = "new" rad

 

Well I tried to recreate the mystery leak experience I have been having by letting the truck idle for an hour. The engine got hot but never left the normal operating temperature bracket. I changed the fuel filter on it today. Next time if it happens I'll have some coolant handy and will find the source of the leak at least.

 

Oh no, I have a tranny leak!

 

I forgot to mention. When it got hot the last time it had some sort of oil or transmission drip. I have been checking both since then and the oil stays the same but the tranny decreases in fluid. So after I let it idle for an hour yesterday to recreate the spillage situation, everything seemed normal, but this morning when I backed up out of my driveway, I put the truck in drive and it slipped and wouldn't go, like a bike without a chain, and eventually caught, so I made it to work. I'm telling you, it acts funny when it runs a little hot

 

Well low trans fluid will heat up the trans same as low coolant will heat up an engine.
Fluid flowing carries away the heat, if you have less fluid then average temp goes up because it doesn't have a chance to cool down before it is sent thru again to collect more heat.

And since the trans cooler is in the radiator that could account for the extra heat you are seeing.

 

I have some of that uv color leak finder stuff maybe I'll put some in the transmission but the leak is SO SLOW! I doubt I would know when I would see it, I really wish I knew what was going on.. If the coolant goes to the transmission and it got hot and I've seen water spew out around the transmission maybe my problem is more along the lines of the transmission and not the cooling system?

 

dye is used so you don't have to catch the leak "in the act" of leaking.
After you add the dye to the fluid any leaks will leave a trail of that dye.

The reason for UV dye is that you can't see it in normal light so you don't end up with "visible" stains on the engine or trans.

So add the dye, drive it for a week then check for UV stains and follow it back to source.