We have a 2001 F150 Supercrew(5.4L/V8, automatic trans) that has a coolant leak somewhere, but only after the truck has been driven, and then parked??. The truck runs fine when we drive it, with the coolant temp in the middle of the gauge, but after it's parked somewhere overnight, it leaks from somewhere. I thought it might be the overflow bottle or cap, but the leak is showing up on the driveway below where the battery is (just inside the left front passenger tire. I replaced the overflow bottle cap & have a new overflow bottle coming. My son (with much better eyesight) can't see where/what it is dripping from, but there is a spot on the driveway?? Funny thing is,we never catch it dripping because it happens well after we have drive the truck and then park it in the driveway overnight. When we come out the next morning, there is a radiator fluid puddle on the driveway. What part of the cooling systems is on the battery side of the truck engine bay? I did put in some coolant dye, and looked over at the heater hoses but I don't see anything, except in the little puddle on the driveway. I will try again later when it is darker outside but if anyone has any advice, please let me know.

Wonder if once the radiator cooling fan shuts off (when we park it for the night) that it boils over for some reason. I don't know, but I am betting people on this web-forum have some good ideas, so please, lets hear 'em!

 

You might need to remove the battery and pressurize the cooling system to pin it down.

 

My son came over and he 1st checked inside the cab under the passenger side of the dash (foot-well) & didn't feel anything wet, nor did he or I smell any antifreeze. I might be wrong, frequently am, but I don't think the problem is the heater core itself. However, with the UV dye and black-light, and looking from the front of the truck towards the front passenger, between the battery and engine, down on the passenger side firewall, down to about what would be just about under where the front passenger's feet would go (again BELOW the cab - not inside) we can see what looks like a little puddle of antifreeze. Not sure if that is just a collection spot, like it is dripping from somewhere else and collecting there in the little puddle. Where do the heater hoses go from the firewall? I think one goes to the top of the engine, where does the other one go? Maybe it's just a bad hose somewhere (I pray! The thought of a heater core change is worse than a root canal!)

 

Hello all: Not being really savvy with computers I believe I received two reply's to my thread, or at least I got an email that said i did. One of the replays is shown below from "HANKY", with some good suggestions. Our email listed the second reply as:"How about some help here? The left side depends on where you are standing. Rather prefer, driver's side or Passenger side for location of leak. Did you ever get the cooling system pressure tester and see where the coolant was leaking when you checked it when the engine was cold?" However, when i came here to the posting, it doesn't show the 2nd reply? I haven't posted this problem elsewhere, and the email didn't say who the reply is from, but there are good questions asked so I will try to answer those questions and give a better idea of what we are dealing with.

I tried to include a picture of a 5.4L engine (not mine/below) with a red circle showing about where I see the coolant puddle, Basically, when I am standing in the front of the truck, looking at the engine, with the radiator closest to me, looking between the battery(front passenger side) and the engine, to about where the two heater hoses go through the firewall. Then looking down from the two heater hoses, to the bottom of the firewall, under the cab, right about below where the front passenger would put their feet inside the cab, is where I see the little puddle of coolant. Again, it is not inside the cab, but below it, We have checked inside the cab below the glove box and there is no trace of coolant. I have to find my pressure tester to pressure test the system, and I believe the cap has to go on the coolant tank, which I believe is the same size as the cap on a 2001 Taurus so I should be good.

I guess the good news is that the leak doesn't appear to be inside the heater core. In doing some research last night, there was an article about a heater hose that goes from the water pump stem pipe, under the intake manifold, to the heater hose near the firewall, that they say goes bad on some Ford 5.4L engines, and leaks down the back of the motor. Mine is a 5.4L/2V but i don't know if the leak they describe is on my exact engine.Does anyone know if there is such a hose on my 5.4L/2V motor

Hope the picture helps you folks see where we see the coolant puddle (again, the motor in the picture is NOT mine, just a picture of another 5.4L so i can give you folks here a good idea of where i see the coolant puddle). Maybe some here have had the same problem/symptoms? The truck has 220,000 miles on it so I can't complain if I have to change the hoses, radiator, and water-pump, as long as it isn't the heater core. I already have a new overflow bottle coming because it looks pretty gross in the current one.

See a little coolant puddle down around where the red circle is.
motor - does anyone know?.

 

The pressure test should help pin down the leak.

 

Hi "Hanky'! Got a chance to pressure test the coolant system. Don't know if it's good news or not, but I don't see any leak coming from the front of the, radiator, or radiator hoses, or the upper intake or thermostat area, or the water pump area. The bad news is that the leak is coming from somewhere at/between the firewall or back of the engine, on the heater hose side of the engine/firewall, which is very difficult to get a look at. However, I don't see any leaks at the heater hose connections on the firewall, nor did I find any leak inside the cab below the glove box or carpeting below dash. So, I learned I definitely have a leak when doing a pressure test, but I just can't find the exact source of the leak when looking up from below, and I can't see the leak source when looking down from above. However, I was unable to really get myself up on the engine and look down but I will try again once I find my inspection camera. All I know now is that the leak is somewhere in the back left side of the engine/firewall area, when standing in front of the truck and looking back towards the windshield (if the hood was down I would be directly in front of the truck on the front passenger side). So somewhere on the left side/or around or below the back left side of the engine. I can't find any heater hose diagrams but I believe there is a hose that comes from under the manifold that has some kind of connection back there. Any ideas?

 

You would be surprised what you can see with a flashlight and mirror.. We can assume a few things, but best to see the source before diving into anything.