2003 F-150 with 5.4 interesting engine problem

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Dec 11, 2009
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Battle Creek, MI
Just to start I'm not looking to fix it, I'm sure the cost will exceed the value of the truck. It has 182,600 miles and slowly has turned into a rust bucket but not as bad as some vehicles.

What I am interested in is anyone has an idea what else could cause the problem other than a blown head gasket or warped head. If it is then I would be inclined to work on it.

Starting as early as December 2014 I had a problem with the coolant reservoir tank over-pressurizing. I would get a whiff of coolant smell in the cab and would check the coolant tank and of course coolant was blowing past the cap. I loosened the cap to relieve the pressure and afterwards every time I tightened the cap till it clicked resulted in the same over-pressurizing. So I drove the pickup for years with the coolant cap loose to no ill effect. I think after I changed the coolant in the summer of 2016 I lost maybe a cup to a pint of coolant until recently.

With the overnight low temperatures getting into the 40s and 50s about a month ago I noticed on my way to work that I would have heat, then lose it, then have heat again. Didn't smell any coolant, but when I got home I probably had lost about 3-4 quarts. As the nights got colder the problem got worse to the point where the temperature gauge would rise normally, then peg to hot. I would stop and coolant was going past the cap, even loosened. However once the air lock worked its way to the top the temperature immediately dropped and ran like normal. Being that it is an old pickup I tried the mechanic in a bottle head gasket sealer in combination with a new thermostat. Surprising at first, it worked until I had to actually drive it somewhere. I tightened the cap down and it would not leak, but at one point the pressure was high enough to leak past a freeze plug and drip down the side of the block.

So what I have decided to do is drive it until it dies. The coolant level is low, only maybe 1-2 inches from the bottom of the tank, I run with the cap loose and I only lose heat for maybe 30 seconds to a minute and it comes back until I turn the truck off. When I lose heat and check the coolant level, it has grown to around the marks for where the coolant is supposed to be when cold. But as I continue to run the truck the air will work its way out of the system and it drops to its original level and the truck never runs hots. The truck also never pegs to the hot mark, it stays in the normal temp range.

Other than that, the trucks runs like I would expect it to. No coolant in the oil, and only the slightest oil film in the coolant tank that probably has built up since 2014. No white smoke, no hesitation, no rough idle, plenty of power.

Any ideas?
 
Joined
Oct 15, 2011
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Your symptoms are the exact(literally) same as an Olds alero with the GM 3800 V6 i had many years ago that had an internally blown headgasket. It also took me a while to find this out because I would never see signs of water contamination in the oil or vice vers. I also tried the head gasket repair in a bottle that worked for approximately one day then it didnt. Ended up changing the gaskets myself, and the gasket was completely blown out on one cylinder and littered with the copper specs of gasket in a bottle, everywhere else looked fine. I was surprised with how blown out the gasket was that it did not cause any visible oil/coolant contamination, and did not effect performance of the motor that much despite so much coolant being presumably leaked into the cylinder, and its something I keep in mind to this day.

The headgasket job was surprisingly quite easy and very cheap, this was back when I was much less experienced with wrenching as well. However, it was a pushrod V6, which is likely less of a headache than a ohc v8 like those fords. I drove that thing for a while with the blown gasket, you could run it till it dies but you will be filling up literal gallons of coolant everyday.
 
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Dec 4, 2013
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Trapped air in the cooling system?

I had this with a 4.6 which should be similar to the 5.4 give or take, trapped air the car would be overheating right away.

Here is a tip that my neighbor gave me, I always had a hard time burping my cooling system after changing the coolant. Now I have a lift but if you dont, just jack up the front end and do your so called burp procedure. Doing it buy yourself is hard, have someone in the car while you do your thing with getting the coolant burped.

I do not care how good Coolant is today, it needs to be changed out between 30K and 50K if you want to keep your vehicle a long time and avoid problems.
 
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May 5, 2013
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Peace valley, Missouri
Just put 1 k in a 03 chevy astro van 220k miles knowing what u have and the price of rides. Could put a few thousand in it drive it for 2 years and hopefully the market will get better.
 
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Dec 4, 2013
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Maryland
Maybe on older iron engines but modern coolant in aluminum engines looks as good at 100K as it does when new.

As long as you do a Voltage Test on the Coolant to make sure there are no Electrolysis issues. Looks can be deceiving!
 

SVTCobra

Thread starter
Joined
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Battle Creek, MI
Your symptoms are the exact(literally) same as an Olds alero with the GM 3800 V6 i had many years ago that had an internally blown headgasket. It also took me a while to find this out because I would never see signs of water contamination in the oil or vice vers. I also tried the head gasket repair in a bottle that worked for approximately one day then it didnt. Ended up changing the gaskets myself, and the gasket was completely blown out on one cylinder and littered with the copper specs of gasket in a bottle, everywhere else looked fine. I was surprised with how blown out the gasket was that it did not cause any visible oil/coolant contamination, and did not effect performance of the motor that much despite so much coolant being presumably leaked into the cylinder, and its something I keep in mind to this day.

The headgasket job was surprisingly quite easy and very cheap, this was back when I was much less experienced with wrenching as well. However, it was a pushrod V6, which is likely less of a headache than a ohc v8 like those fords. I drove that thing for a while with the blown gasket, you could run it till it dies but you will be filling up literal gallons of coolant everyd
I forgot to mention that a few years ago when I changed the spark plugs I did a compression check and two cylinders were low and were right next to each other. I remember reading that meant the cylinder head gasket was the culprit, but ran fine so I didn't do anything.

I've probably put on 50k miles with this condition and just now in the colder temps it has deteriorated.

I've read this is a $2500 job as the engine needs to be removed and KBB says in fair shape it's worth$2700. Don't think it can account for a major repair like this, so essentially it's worth scrap. Normally I would try something like this myself but going into winter without a proper heated workshop, I'll pass. So I'll just see how long it lasts. Ran fine all summer long so wondering if the ambient temp has anything to do with it.
 
Joined
Oct 15, 2011
Messages
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I forgot to mention that a few years ago when I changed the spark plugs I did a compression check and two cylinders were low and were right next to each other. I remember reading that meant the cylinder head gasket was the culprit, but ran fine so I didn't do anything.

I've probably put on 50k miles with this condition and just now in the colder temps it has deteriorated.

I've read this is a $2500 job as the engine needs to be removed and KBB says in fair shape it's worth$2700. Don't think it can account for a major repair like this, so essentially it's worth scrap. Normally I would try something like this myself but going into winter without a proper heated workshop, I'll pass. So I'll just see how long it lasts. Ran fine all summer long so wondering if the ambient temp has anything to do with it.
Right on. Yea the gaskets on that olds were a breeze because it was pushrod which not only means you dont have to mess the with cams at all but also the heads are tiny, making it way less of a hassle than overhead cam V motors like your ford. I did a quick image search of the engine bay on your model truck and while it looks like doing it with the engine in is possible it would be a massive PITA, so a major job any way you look at it. Would probably be easier to buy a used engine and swap it in, a PITA itself.

Mine would lose lots of coolant for a couple days, then be fine for a few, then bad again etc etc for many months. Like yours, in the summer it wasnt that bad and was manageable. It started to lose coolant consistently in a very gradual manner then one winter I had to put in at least a jug of coolant everyday. I remember it was winter cause the heat would blow red hot to completely cold about 20 mins into my commute, then my temp would spike a couple mins after. Thats when i tried the in bottle HG repair stuff, then the repair.

I would just run it till you have to start putting in a jug of coolant everyday, it will take a while to die even in that state, and a jug of coolant a day is a huge pain and expensive even if you mix it yourself.
 
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Maybe on older iron engines but modern coolant in aluminum engines looks as good at 100K as it does when new.
The engine in question is an iron block. There were issues with these engines having voltage in the cooling system and damagingcomponents including the heater core. Ford was having techs put in additional grounds on vehicles with multiple issues. Usually replacing every piece of the cooling system, including the heater core, radiator, engine, and all hoses, ended up fixing it.
 

SVTCobra

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Joined
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What I ended up doing is putting another overflow tank that sits higher than the normal overflow coolant tank and connected them together. There is a short hose that connected the top of the radiator to the top of the coolant overflow tank, put a tee and routed that to the additional overflow tank. For a minute or so I lose heat in the cab but the air will escape and the coolant flows back into the radiator. Been driving like that for a few weeks now and seems to be doing okay.
 
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