# Truck over heated, what could be the problem?



## raylo32 (Nov 25, 2006)

It could be the water pump but those usually leak and are obvious. More likely it's a failed thermostat The thermostat is closed when cold to bypass the radiator to speed up warming. It is supposed to start opening at a temp usually about 180 F and bring the radiator online. If it sticks, the engine will overheat quickly which is what you say happened.


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## Steve2444 (Sep 28, 2020)

On that mileage engine, who knows? But at 5 deg F? To go a few miles and over heat it sounds like your antifreeze, froze.


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## Nealtw (Jun 22, 2017)

What colour is the oil?


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## raylo32 (Nov 25, 2006)

That is certainly a possibility if the coolant has been neglected or diluted.



Steve2444 said:


> On that mileage engine, who knows? But at 5 feg F? To go a few miles and over heat it sounds like your antifreeze, froze.


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## HotRodx10 (Aug 24, 2017)

Could be the water pump, but to have it happen suddenly like that, without alot of noise (I assume if there was a new noise associated with this, you'd have mentioned it) is unlikely. If the 5 degrees represents the coldest the temperature has been recently, I would strongly suspect the your antifreeze is diluted too much, and it was frozen.

Antifreeze testers are less than 5 bucks and available everywhere. I would pick one up and use it. If it shows it's not concentrated enough for the lowest possible temp in your area, you'll need to get more antifreeze in the mix. I would drain the radiator, and refill it with a 60% antifreeze/40% distilled water mix. That's my best guess of what would give you the optimal mix (50/50), based on it not freezing until it hit 5 degrees and my assumption of the amount of coolant that will be left in the engine. I'd check it again with the tester after running it for 15 minutes after it gets up to operating temperature, just to make sure it's adequate.


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## Nealtw (Jun 22, 2017)

HotRodx10 said:


> Could be the water pump, but to have it happen suddenly like that, without alot of noise (I assume if there was a new noise associated with this, you'd have mentioned it) is unlikely. If the 5 degrees represents the coldest the temperature has been recently, I would strongly suspect the your antifreeze is diluted too much, and it was frozen.
> 
> Antifreeze testers are less than 5 bucks and available everywhere. I would pick one up and use it. If it shows it's not concentrated enough for the lowest possible temp in your area, you'll need to get more antifreeze in the mix. I would drain the radiator, and refill it with a 60% antifreeze/40% distilled water mix. That's my best guess of what would give you the optimal mix (50/50), based on it not freezing until it hit 5 degrees and my assumption of the amount of coolant that will be left in the engine. I'd check it again with the tester after running it for 15 minutes after it gets up to operating temperature, just to make sure it's adequate.


What do you think happens when the water in an engine freezes.


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## raylo32 (Nov 25, 2006)

The block has a lot of thermal mass and is a heat sink so what happens is that the coolant in the small radiator channels freezes first. This can happen before the coolant in the block freezes and pops the freeze plugs or does other damage. That ice in the radiator prevents flow once the thermostat opens.... IOW it is like the thermostat never opened and the only flow is bypassing the radiator. The hot water may begin to thaw some of the initial radiator channels but the extreme cold and driving the truck will keep the bulk of the radiator from thawing in time.



Nealtw said:


> What do you think happens when the water in an engine freezes.


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## HotRodx10 (Aug 24, 2017)

Nealtw said:


> What do you think happens when the water in an engine freezes.


I know what happens when it freezes hard, and it's sometimes very messy, but for the reasons raylo32 mentioned, that doesn't usually happen. More often, the radiator partially freezes, turning the coolant into slush that won't circulate.


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## Nealtw (Jun 22, 2017)

HotRodx10 said:


> I know what happens when it freezes hard, and it's sometimes very messy, but for the reasons raylo32 mentioned, that doesn't usually happen. More often, the radiator partially freezes, turning the coolant into slush that won't circulate.


I wouldn't replace anything before I knew the engine is not broke. The first thing is to look for water in the oil.


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## HotRodx10 (Aug 24, 2017)

Nealtw said:


> I wouldn't replace anything before I knew the engine is not broke. The first thing is to look for water in the oil.


Well, one of 3 things to look for; the other 2 would be sweet-smelling white smoke from the exhaust and coolant on the ground under the truck.


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## Perps (Jan 19, 2021)

Thanks for all the advice and suggestions. I'll thaw everything out and replace the coolant and go from there. I'll report back if there's more issues.


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## Dave Sal (Dec 20, 2012)

Have you been hearing a slight clanging sound recently? This is a Ford product. For some reason they use internal water pumps. When they fail, you have to remove the front of the engine to replace it, as it is driven by the timing chain. 

My wife has a 2010 Flex and suffered an overheat this past spring. For a couple weeks she would come home and say that the engine was making a funny noise. I'd go out and start it up and never heard anything unusual, except for one time when I thought I heard some clanging sound. 

It ended up overheating a couple weeks later. Fortunately it was shut down right away and suffered no engine damage but the repair was about $2500. No more Fords here until they stop with this horrible design. A water pump should be an inexpensive job, maybe $300 or so.


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## raylo32 (Nov 25, 2006)

If he shut it down quickly the head gaskets should be fine. Only the OP knows how far it got and whether this is even worth looking into. If I were him I'd get it somewhere warm to keep it from refreezing and see what's going on. Probably just needs fresh coolant and maybe a thermostat.



Nealtw said:


> I wouldn't replace anything before I knew the engine is not broke. The first thing is to look for water in the oil.


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## Nealtw (Jun 22, 2017)

raylo32 said:


> If he shut it down quickly the head gaskets should be fine. Only the OP knows how far it got and whether this is even worth looking into. If I were him I'd get it somewhere warm to keep it from refreezing and see what's going on. Probably just needs fresh coolant and maybe a thermostat.


He said it was 5* F. If he drove it and got lucky sure, is it still parked in cold, that would be plenty of time to break the block.


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## raylo32 (Nov 25, 2006)

And the antifreeze may have been weak but still sufficient to prevent a full engine hard freeze with catastrophic damage. Could just be a slush puppy. No reason to leap to the worst possible conclusion until there is evidence. Again, it's hard to know it all from here at a remote keyboard.



Nealtw said:


> He said it was 5* F. If he drove it and got lucky sure, is it still parked in cold, that would be plenty of time to break the block.


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## Nealtw (Jun 22, 2017)

raylo32 said:


> And the antifreeze may have been weak but still sufficient to prevent a full engine hard freeze with catastrophic damage. Could just be a slush puppy.


Could be, all I am saying is you check things before you start spending money.
On a bad day you could have leaks from frost plugs on the side or back of a block. 
On a real bad day you crack the block.


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## Nut'n'Done (Nov 28, 2021)

It would be worth checking the serp belt and tensioner.
Push down on the belt tensioner and see if it seized up.
You didn't mention an engine light, so I would assume the TCS would be ok.
I would also check to see if you have power to the fans, broken blades, obstructions in the radiators path.

Neal makes a good point on the head gasket check before dropping money.
A radiator pressure test will work in this case.
The system should hold 18 psi consistently for at least a few hours to be checked properly.

I hope it works out.


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## Perps (Jan 19, 2021)

All right I drained the old coolant and put fresh 50/50 mix in, ran it until it got up to temp and no overheating, and the heater is now blowing hot air again. I pulled the dipstick and the oil looks fine, but I don't really know what it's supposed to look like other than regular motor oil. What should I be looking for in the dipstick? Anything else I should check before I call this a lucky close call?


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## raylo32 (Nov 25, 2006)

Should be good to go. If you did damage the head gaskets you might see some oil or creamy stuff in the coolant reservoir or steam coming out of the oil fill tube. Stuff like that. Just keep an eye on it for a couple of days as it goes through some heatup and cool down cycles.



Perps said:


> All right I drained the old coolant and put fresh 50/50 mix in, ran it until it got up to temp and no overheating, and the heater is now blowing hot air again. I pulled the dipstick and the oil looks fine, but I don't really know what it's supposed to look like other than regular motor oil. What should I be looking for in the dipstick? Anything else I should check before I call this a lucky close call?


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## njt.manitoba (Dec 23, 2021)

Perps said:


> All right I drained the old coolant and put fresh 50/50 mix in, ran it until it got up to temp and no overheating, and the heater is now blowing hot air again. I pulled the dipstick and the oil looks fine, but I don't really know what it's supposed to look like other than regular motor oil. What should I be looking for in the dipstick? Anything else I should check before I call this a lucky close call?


Oil should not be Milky if it's milky looking or white you got moisture in it, drain and replace filter, go from there.


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## raylo32 (Nov 25, 2006)

One thing we did not discuss... before you filled it with new coolant did you drain the block? The block should have a couple of drain plugs that you can pull to drain it. If not you will still have a lot of that old coolant in there and if you added 50/50 to refill just the radiator you are still going to have significantly less than 50/50 overall in the system. Use a tester to see where you ended up and what temperature you are safe down to. They sell them cheap at the auto stores... or maybe a service station will do it for free.


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## Nealtw (Jun 22, 2017)

Perps said:


> All right I drained the old coolant and put fresh 50/50 mix in, ran it until it got up to temp and no overheating, and the heater is now blowing hot air again. I pulled the dipstick and the oil looks fine, but I don't really know what it's supposed to look like other than regular motor oil. What should I be looking for in the dipstick? Anything else I should check before I call this a lucky close call?


If you had water in the oil you would have known right away. It looks more like a milk shake than oil.


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## HotRodx10 (Aug 24, 2017)

raylo32 said:


> One thing we did not discuss... before you filled it with new coolant did you drain the block? The block should have a couple of drain plugs that you can pull to drain it. If not you will still have a lot of that old coolant in there and if you added 50/50 to refill just the radiator you are still going to have significantly less than 50/50 overall in the system. Use a tester to see where you ended up and what temperature you are safe down to. They sell them cheap at the auto stores... or maybe a service station will do it for free.


That's why I suggested adding a 60/40 mix, because you only get about 2/3 of the coolant out when draining the radiator. Draining the block is a PITA, and unnecessary unless there is major contamination in the system. Even then, I'd get one of the flush and fill kits that back-flushes the system from one of the heater core lines, instead of trying to drain the block.


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## HotRodx10 (Aug 24, 2017)

Nealtw said:


> If you had water in the oil you would have known right away. It looks more like a milk shake than oil.
> View attachment 677105


Hey, that looks just like the one I took off my son's truck yesterday! Of course, we knew it was going to look like that; that's why we're replacing the engine.


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## Nealtw (Jun 22, 2017)

HotRodx10 said:


> Hey, that looks just like the one I took off my son's truck yesterday! Of course, we knew it was going to look like that; that's why we're replacing the engine.


If it didn't freeze, that is usually just a head gasket.


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## HotRodx10 (Aug 24, 2017)

Nealtw said:


> If it didn't freeze, that is usually just a head gasket.


Most likely the head gasket is blown, but in this case, I'm fairly sure it's a symptom of a larger problem - a warped head. The intake and exhaust manifold connections to the head have also developed leaks. It has nearly 200k on it (expected life for that generation of engine), and the compression was low before it dumped all the coolant into the oil. We may attempt to rebuild it, depending on how bad it turns out to be once we tear it down.


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## 3onthetree (Dec 7, 2018)

There are many demons to chase. Besides what has been offered, it could be as simple as your radiator fins are mucky and need blown out. It could be your engine coolant temperature sensor. It could be an air pocket. It could be a rusted heater core that sent debris beyond itself. It could be a collapsed lower rad hose.

If you do find it to be the thermostat or water pump, be very careful about brands - it's hit or miss. "Usually" OEM is safe.


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## Nealtw (Jun 22, 2017)

3onthetree said:


> There are many demons to chase. Besides what has been offered, it could be as simple as your radiator fins are mucky and need blown out. It could be your engine coolant temperature sensor. It could be an air pocket. It could be a rusted heater core that sent debris beyond itself. It could be a collapsed lower rad hose.
> 
> If you do find it to be the thermostat or water pump, be very careful about brands - it's hit or miss. "Usually" OEM is safe.


In the nineties a friend had just opened an auto repair shop so I gave him my GMC to change the heater core.
After 2 failures with cores from GM, he figured how to pressure test them with a garden hose.


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