Hello all. Been driving the '99 F250 SD 5.4L Ext Cab 4x4 a lot lately and had an issue today. First time I have ever been stranded in a Ford.

Anyways, we had 15 degree weather here last night which is unusual for this area. I have always just added water to my coolant mix as freezing temperatures are rare. Most of the fluid in the tank / truck was water, so please consider that.

I woke up this morning and started the truck I idled it for about 10 minutes to warm it up since it was cold out and I have a 30 minute drive. All systems go and all gauges fine. I was driving down the highway, about 10 miles into my drive (65 with the cruise set the whole way) and the temp needle start going up pretty quick. Wasn't really sure what was wrong at the time. Parked immediately and steam started rolling from under the hood. Waited about 5 minutes and opened hood. Water was running from under the vehicle and was on most things under the hood. Had a trail behind me as I pulled in. Waited about 15 minutes the fill tank was still empty and truck temp needle was below half. Called a wrecker and got towed home later in the evening. When I got home I filled with 1/2 antifreeze and water slowly to check for a leak. Nothing. No hoses off or split. Started the truck up. No funny sounds or vibrations. Let it idle for about 10 minutes. Needle had barely budged above the start point (still only 29 degrees out). Decided to take it for a test drive around the block. Within 100 yards needle had already moved to 20-25%. Drove back home, popped hood. Didn't notice water level change. Drove again about 100 yards, needle moved about 10% more. Water level didn't seem to change. Drove around the block. Needle on normal levels. Drove more giving it a bit more juice than usual. Needle seemed normal. Water level did drop, but I could hear some filling the heater core and what not. Parked the vehicle. Checked fluid again and no change after cooling down.

Doesn't seem like a thermostat problem, but I think the water pump may be beginning to fail. Anyone have an opinion? Am I way off? Please help! Thanks in advance!

 

You have to find out where the coolant is coming from, could be from lots of places. This is most likely a self-inflicted failure though, antifreeze does much more than just prevent the mixture from freezing. Water will corrode everything in your cooling system without the anticorrosive additives in your antifreeze, and these additives become depleted over time.

Sounds like you're paying the piper for lack of proper service. I'm willing to bet you have a corrosion failure somewhere. Check the weep hole in the front of the water pump, did it leak from there? How 'bout the radiator?

 

Well, water was on everything under the hood. Battery included. I did see a small trace of rust in the water, but I have seen way worse before on an F150 I owned in the past.

I tried to replicate the error again, but was unable to today. Was scared to take if for a long haul without at least asking around first. I didn't get a good look at where the water came from when it leaked. There was water around the cap on the fill tank also, but that didn't necessarily mean that is where the water came. Just noting that even the highest area closest to the front had water on them also.

 

Does the coolant system build pressure when up to operating temp. When water/coolant freezes it expands and can crack blocks, cylinder heads and etc.

Water pump is less on hassle to replace on a 5.4l or 6.8l in a SD than the 302 in old F-100. I changed my dads last summer with a new AC Delco pump. You could get a replacement water pump o-ring at least, pull the pump and see how everything looks. At 15 years old it is probably not in the greatest shape. But look the truck over good and see if you can find any obvious cracks of leaks first.

 

It could be your radiator cap intermittently making a good seal on the radiator. I would get the system pressure tested at a shop. That alone will tell you if your cooling system has issues or not (it does).

Tom is right about the antifreeze. You can't just keep adding water and expect everything to be OK just because you've seen coolant with more rust in it than your truck has. If your coolant is even a LITTLE bit rust colored then you have already neglected the system and a complete flush is in order.

But then again, I have a funny thing about NOT wanted to get stranded in my truck...

 

My best guess here....the water in your engine didn't have a high enough concentration of antifreeze in it...so it froze. The reason your truck over heated.....the water pump was unable to circulate any water through the rad...With the engine running it thawed the water in the block only and since nothing was able to circulate...that water in the block over heated. Anything freezing in an engine block or any cooling systems can be very bad news....you can pop a frost plug.....your water pump trying to churn through ice won't like that very much as well as many others.

 

I don't think that's very likely. The OP lives in an area that doesn't commonly see freezing temperatures, and despite topping off with water it's likely there was still a good amount of antifreeze in the system. Probably worn-out antifreeze that's no longer protecting against corrosion though.

If water freezes in the block the casting plugs aren't likely to be of any help. This is commonly seen in marine applications with raw water cooling when engines don't get winterized. Virtually 100% of the time the block is destroyed and the casting plugs stay in place. They're not meant for freeze protection, that's an urban legend.

 

Unless I'm missing something here the OP said temps got down to 15 degrees....Mind you i'm assuming 15 Fahrenheit? Last I checked water freezes at 32 degrees Fahrenheit or 0 Celsius where i'm from.

 

Right, but he never said he drained the system and had 100% water running in it. It only takes 21% antifreeze concentration to protect down to 15°. And it would take a LONG cold soak at 15° to get the block core temp down that low. Dipping down that far for a few hours wouldn't bring the water temp that low.

 

Anyways, we had 15 degree weather here last night which is unusual for this area. I have always just added water to my coolant mix as freezing temperatures are rare. Most of the fluid in the tank / truck was water, so please consider that.

This is what I am basing my opinion on....he asked for thoughts and possible causes. 15 degrees F is -9 degrees C and will freeze water fast. I do hope that he had at least 21% antifreeze in it though, like you said...doesn't take much antifreeze to keep water from freezing.

 

If you leave a glass of water out overnight, and the temp gets as low at 15, yes it will freeze. However, 4 or 5 gallons or more of diluted anti-freeze surrounded by a few hundred pounds of cast iron is an entirely different story and it will take considerably longer to freeze.

Additionally, just because the temp got down to 15 probably means it was that low for an hour at most.

So no, I don't think it froze.

 

SXRFUN
x2 on the coolant freezing blocking coolant flow and pressure buildup

 

Thanks for everyone chiming in. I have been keeping an eye on the truck and the fluids. I am the appropriate level of coolant now. Probably close to a 50/50 mix with water and coolant. Added a little oil and a little tranny fluid to the system to get ready for more driving. I have been driving locally and have had no issues. Truck seems to be running fine and warming up to the temps I was used to seeing. I havent taken the truck on the 25 minute commute to work yet, but will likely do so this week. As for now, the coolant levels seem to be sustaining and I haven't noticed any under the vehicle. I checked around the water pump to see any wetness and there was none. Hopefully it was just a fluke. Sucks I got her towed home, but I like to play safe instead of sorry when it comes to overheating. I'll keep a close eye on it and let you guys know how it goes. 10 day forcast shows freezing temps Monday, Thursday and Friday (only about 28-30 degrees, probably for a couple hours).

 

I am going to agree with most of what was previously stated. But it was caused by freezing.


No current leaks, no blown hoses, water leaking at fill tank. = over pressurized system due to boiling water/coolant IN engine with the radiator fins frozen solid.


The pump was probably not frozen solid. If it was, it would not have turned and the belt would have slipped and burnt off or at least squealed loud enough to be heard. The hoses may not have been either or the water would not have gotten to the relief cap. They could have expanded enough to let the steam get by or there could have been enough air at the top of the system. I'm betting the entire system was not full.


Because,


The coolant concentration also determines the boiling point. If it was too low to prevent freezing, it was too low to stop the boiling. So over time I would expect that some was released.


So my theory is that coolant in the radiator fins did freeze. Remember, they are made for heat transfer and you only have a space of about an eighth of an inch wide inside with a lot of surface area.


Engine starts, takes awhile to heat up the block and coolant. At idle and no load it doesn't get too hot, too fast. Starts driving. Thermostat opens, the hot water has nowhere to go. Just recirculates. Keeps getting hotter. Starts to boil. Builds pressure. Boom!!! Relief valve opens. Keeps everything safe.


Keep an eye on it. It should be fine for now. Keep a bottle of 50/50 mix handy if you need to top it off again.


I would probably do a flush on it when the weather gets warm. If that ever happens this year.

 

Huh, I never even considered that rcbuehler. But it makes perfect sense that the water in the radiator would stay at ambient temperature more than just about anything else on the truck. So cold temps could have frozen and obstructed the radiator. With the radiator blocked the water pump would still function normally, but the system would behave exactly like if the thermostat was stuck closed.