I have an '03 Ford E-250 with 4.6 engine. This is one of 3 service trucks used in my business and it has been a great truck and very reliable with fairly low miles relative to it's age. For the past month we've had higher than average temps here and one day while running a svc call in 95 deg temps with air on, it overheated. I detected a slight smell of coolant and then glanced at temp gauge and it was in the red. After letting it sit for 1/2 hour I checked coolant level and it was good which made me wonder why I smelled coolant yet there did not seem to be enough of a leak for it to overheat but it did in fact have some coolant that had leaked from under radiator cap on tank which lead me to believe t-stat was the issue. I started it back up and drove it without the air on to get it back to the shop. I noticed so long as I kept AC off and was moving down the road it did not overheat again during the 6-8 mile trip back through heavy traffic. Since the t-stat had not been changed since we owned this truck I went ahead and replaced it along with radiator cap and it did take just over 1 gallon of coolant to fill it although quite a bit was lost via removal of t-stat housing and hose. I drove it for 2 days also using AC again and all seemed well until the late afternoon of 2nd day and I once again detected coolant smell and sure enough, there it was in red zone on gauge again. T-stat and rad cap were obviously not the problem. I have been all over this thing looking for a coolant leak and also looking on the ground underneath it and have found absolutely no wet spots. I've looked over the radiator, the intake manifold, hoses et al. The only thing I have not done is remove heater core box cover. I have let it sit in driveway running both AC and heat to see if windshield fogs up and it did not after 1/2 hour or idling and heating up. I've checked the oil for signs of coolant in oil and there is no coolant in oil. I am aware these htr core boxes have a drain and would think if the core was the issue I would see some dripping of coolant underneath on that side but I have found none. I am at a complete loss as to what the issue is and where the coolant leak is. I'm sure plenty of you guys know these trucks better than I do so I thought I would ask for any info you might be able to add or advice as to what I need to check that I have missed. Thanks in advance.

 

How many miles does it have? How often has the cooling system been serviced? I would start with the basics. Clean dirt bugs and debris from the cooling fins of the condenser and radiator and check to see if there is seriously bent fins. Check clutch fan. It may be an AC issue causing the refrigerant to get to a higher pressure and heat and the cooling system can't handle the extra load on the hot days.

 

When the A/C is running it does add a small heat load to the air flowing through the radiator but even if the A/C is having issues it typically doesn't cause coolant issues. FWIW I have a 2003 E250 extended body with 5.4 that had a similar issue as you describe---I was able to monitor the coolant temperature as seen by the PCM with a scanner---it would reach 230* but only after a sustained highway run then pulling over at a rest stop or similar with the engine still running. It would quickly drop back to under 200* while idling, A/C on or off, didn't affect the coolant temps.

I found a leaking under pressure degas bottle, very poor condition pressure cap--both replaced with OEM parts from the dealer--best prices I could find believe it or not. Cost just under $100. The same issues were still present soI opted to replace the fan clutch (Motorcraft YB-3016) and radiator (aftermarket/imported)---combined those two parts cost me about $200. DIY install. That was nearly a year ago, about 20K miles and everything is running proper regardless the ambient temperatures.

You might have your A/C system checked for the proper refrigerant level, definitely clean the condenser of any dirt and debris but that shouldn't be the biggest cause of your overheating condition.

HTH

 

I just went through an overheat situation with my 1990 E350 with 460 engine. Had to replace the radiator as it was full of mineral deposits choking off the tubes.

If you are smelling coolant, then that coolant must be coming out from somewhere. You need to find the leak. It sounds like you saw some near the fill neck? It's possible the system reached max pressure and vented. Does your system have a catch tank? Mine does not and there is just a rubber overflow tube so it will dump on the ground.

When your engine is cold, I recommend removing the radiator cap and look inside with a flashlight. Hopefully yours is set up so that you can see the ends of the core tubes. If your coolant is murky, you may need to drain some to see them with a flashlight. On mine, they looked like Yellowstone National Park - there were hard mineral deposits around all the tube mouths and many were partially or fully plugged, which is why the radiator was no longer functioning well. I tried two different runs with "Radiator Flush", letting it sit in the system while I ran it as a daily driver for a week. Nothing. I don't know what those radiator flush products are supposed to do, but they cannot touch mineral deposits.

So, I replaced the radiator. Problem solved.

I am also now a believer in using only distilled water (with antifreeze of course) in my radiator.

Steve

 

Thank you for the replies. No cap on radiator itself. My '03 E-250 has the cap on a plastic tank on driver side. The first day it overheated I saw coolant on the tank which came out from under cap.. Just to rehash, I replaced T-stat and while I was at it went ahead and put a new cap on tank as well. 2 days later, it overheated again but this time no fluid coming out from under cap on tank though my first warning was again smelling hint of coolant odor..In fact, I can't find any leaked coolant at all this time and I've been up down and all around this thing. Radiator is clean as well. I thought possibly hot combustion leaking into coolant via blown head gasket or something along those lines but no air bubbles in catch tank and no coolant getting into oil pan either. Fan also seems to be putting out a lot of air when engine is warmed up as well. I have taken a flashlight and looked back at heater core coolant lines and don't see any leakage there either at least at the core and the hose connection at other end that I can see. One of the hoses I cannot see from front of engine. To see the other end of that one I believe I have to remove the console engine cover on inside of truck. With the radiator essentially being sealed from internal visual inspection I would think I could take temp measurements up and down tube ends to try and detect internal clogging(?). much the same way I check condenser coils with laser thermometer. We've been swamped with work so I haven't had a lot of time to fool with it and have been using one of the other svc trucks. Been going over it in my mind as to all the possibilities to check into when I get back to it. I don't work on these things for a living though so I'm sure many of you know far more about them than I do.

 

My 97 5.4 E250 cargo van overheated once in 2400000 miles. In traffic, on a 95+ day in Austin TX. I noticed the temp gauge climbing which it NEVER does. Once moving, the temperature dropped but, before I could get out of traffic and stopped, it overheated and cracked the plastic radiator.

I believe the fan clutch failed because it would cool fine as long has the van was moving. Once it got hot, the pressure built up enough to crack the old, brittle plastic tank/radiator.

I replaced the radiator and fan clutch and have no further issues.

These things hold 30 quarts (7.5 gallons) of coolant. They never overheat unless something is bad.

I bet your fan clutch died.

 

That is very interesting. I did notice the first day it overheated that I was able to get it back to the shop so long as I kept AC off AND kept moving. I don't see any fluid leaks anywhere on radiator but your issue with fan really is beginning to make me think that may well be the issue. It does SEEM like it's putting off a lot of air while idling but seem and actually working correctly can be a big difference I know. I suppose I could stick my hand in there to see if blades are actually spinning ;-) About 6 or so years ago we had a crew leader(Commercial HVAC) actually do the same exact boneheaded move when not sure if a condenser fan was running on a 24 ton Carrier RTU. Needless to say he got his hand beat up good and he's also no longer working at our company. Thanks for your example I think you may be onto something!

 

My tank had cracked too, replaced the fan clutch while it was all apart, I never saw my gauge rise to half, you got me thinking my gauge isn't reading correct now, I fixed it 8 years ago but your reply has me now thinking about it.

 

Okay. Finally got around to replacing water pump, fan clutch, belt, t-stat, new coolant, tank cap etc etc. Drove it today with AC on and within 5 miles it overheated yet again. No loss of coolant but overheated just the same. I have checked for all the potential symptoms of a blown head gasket and have found none. No bubbles in tank, no milky oil etc. While I have it all apart I used coil cleaner on the condenser coil and hosed it off, blew/hosed out the radiator fins, made sure water was running through radiator with hose and on and on. Also checked to see if heater core was leaking and it isn't. I'm nearly ready to have this thing hauled off for scrap. Frankly I've not run into such a tough situation before when dealing with an overheating issue on any vehicle and I honestly do not know what else to check or consider at this point.

 

Well, crap.

When it's hot, can you hear the fan kick in?
There's no mistaking it when it does.
It happens so rarely on mine (100+ day, in traffic, with tailwind or similar) it's surprising.

Do you have in IR thermometer?
Maybe check the upper and lower inlet temps, thermo housing temp, etc?

Air in the system? Not usually in issue with a degas bottle but we're grasping at straws here.
I like the thermostats with a bleed hole - almost universal now.
If not, a 1/8" bit solves the problem.
Can also fill system with the EC sensor out until coolant runs from it, then top off from there.

No coolant loss is a wrinkle.

 

Did it hold the required coolant, I have seen people change coolant and declare it done, ignoring the fact it was full long before it should be, their radiator was full of scale, so less coolant was required, father in law did so on his Ranger, held only one gallon, the radiator felt like it was full of lead when he pulled it. Only thing else I can suggest is get the AC checked, I had a Dodge once that did the same, the charcoal canister had ruptured, sending debris throughout the system, causing a load on the engine.

 

My own 2003 with 5.4 had these same issues---I'd done much the same as you before finally just replacing the radiator. Like you I also ran water through the radiator and it seemed to flow out as quickly as it entered--I'd expected to see it over flow from internal restrictions but no. Mind you a garden hose is maybe 35 PSI and 55* F so its not that reliable a test for heat transfer.

I'm using a good quality aftermarket radiator---have a friend in that business---so along with everything else I've changed it seems the radiator itself was the biggest cause of my elevated coolant temps.

Good luck with your solution!

 

Agreed on it's a good probility that the radiator is the cause.

 

One thing I don't believe I have mentioned is the fact that I had a blown out spark plug replaced and the good insert installed by a guy who specializes in repairing these Triton engines back in April. It has been running perfectly since then however I just wonder if it is remotely possible that the repair has anything to do with the overheating situation I am dealing with now(?) It was the rear-most plug on passenger side at back of engine.(closest to inside engine cowl) Not sure what plug # that is. As I've said, I see no signs of a blown head gasket at least the ones I know to look for i.e. bubbles in radiator tank, milky oil, loss of power etc. A new radiator for this thing is $176.99 which isn't a lot but if in the end replacing the radiator still doesn't solve the problem I am going to finally have to give up on trying to figure it out. Like you guys who have called out the radiator, I also cannot think of what else it could possibly be but I hate just blindly hanging parts on anything I work on. For one it gets expensive and for another there are times when it doesn't even end up fixing the issue. I've seen it happen to guys often over the years in my own line of work. Then they've got a bill for a customer that's $1,000 instead of the real issue being repaired for $150 if you see what I mean. I prefer diagnostics but working on these is not what I do for a living so I can only do what seems precipitous to fixing the problem with what knowledge I do have when it comes to vehicles as opposed to what I myself do for a living every day. I guess at this point I'm left with going ahead and getting a new radiator in it and hoping for the best. I'd also hate to have a truck hauled off for scrap with a new radiator, water pump, fan clutch, t-stat and cap in it along with 5 gallons of coolant.


As an aside, do any of you know where the engine temp sensor is located on the Ford E250 with 4.6? I am going to replace that as well. Just don't know where it's located.

 

I understand your frustration, been through this type of event many times. I would have replaced the radiator before doing a water pump. As long as they're not leaking they're usually good. How many miles are on the van, and what kind of shape is it in? Even if you have to dump more money into it you're probably still ahead considering what a new van costs.