What gives?
Senior User
Joined: Mar 2006
Posts: 330
Likes: 2
Sorry for so many post, but this just came to me. You can also have a radiator hose that is collapsing. Squeeze your radiator hoses and make sure they are not soft. Sometimes they can squeeze up and block flow of coolant and then release moments later causing temp fluctuations.
Senior User
Joined: Mar 2006
Posts: 330
Likes: 2
That might not be enough time. On the diesels, you have to take it up on the highway and step on it, and maybe as long as a week or more if you just drive casually (of course you got to keep an eye on your temps and coolant level. This is why it is really best to vacuum fill to save all the grief.
Posting Guru
Joined: Sep 2013
Posts: 1,348
Likes: 6
From: Edmonton, AB
I own a few 5.4's and always use the FoMoCo thermostats and filters, The after market ones can be good but they can also fail. If You did your own coolant change , there is a chance you have some air still in the system, you may be able to go to your local Auto zone and rent their little pump doohickey that will allow you to purge some of the air out of the system.
You definitely want to make sure you have the air out of there.
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Freshman User
Joined: Dec 2016
Posts: 42
Likes: 0
Motorcraft thermostat in. Truck warmed up to 228 and I shut it down. Then all of the sudden, it opened and it ran fine for a while. Shut it down and went back to work, came home and took it to go pick up the kid from school. Within 15 minutes it was at 228 again with no sign of it opening. Not really sure what's up with this thing. I am still suspicious of air pockets.
Elder User
Joined: Dec 2016
Posts: 568
Likes: 2
do you ever lose cabin heat in the truck when it starts running hot, or does the heater keep going, even when the temps climb? if you lose heat and the truck runs hot, that's an obstruction in the cooling system like a bat T-stat.
If you don't lose heat, another possibility that you should start considering is that you might have a bad head gasket. A bad head gasket can both introduce air pockets into the system and consume coolant into the combustion chamber. A look at the plugs should be a good first step. If a cylinder or two are leaking, you'll see plugs that look different from the others (from being steam cleaned by the coolant). If you find a goofy plug or two, a compression and/or leak-down test should be step 2.
If you don't lose heat, another possibility that you should start considering is that you might have a bad head gasket. A bad head gasket can both introduce air pockets into the system and consume coolant into the combustion chamber. A look at the plugs should be a good first step. If a cylinder or two are leaking, you'll see plugs that look different from the others (from being steam cleaned by the coolant). If you find a goofy plug or two, a compression and/or leak-down test should be step 2.
Elder User
Joined: Jul 2005
Posts: 533
Likes: 0
From: NorCal
Check for blown head gasket(s). We have a 5.4 3-valve in our fleet that did the same exact thing. Will be fine at one point then overheat at times, even unloaded. Had the coolant system flushed, water pump, t-stat, etc all done w/OEM parts. Even changed out the cylinder head temperature sensor.
It ended up being bad head gaskets. Replaced the head gaskets and 30k miles later, she's still working hard with no issues.
It ended up being bad head gaskets. Replaced the head gaskets and 30k miles later, she's still working hard with no issues.
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Freshman User
Joined: Dec 2016
Posts: 42
Likes: 0
do you ever lose cabin heat in the truck when it starts running hot, or does the heater keep going, even when the temps climb? if you lose heat and the truck runs hot, that's an obstruction in the cooling system like a bat T-stat.
If you don't lose heat, another possibility that you should start considering is that you might have a bad head gasket. A bad head gasket can both introduce air pockets into the system and consume coolant into the combustion chamber. A look at the plugs should be a good first step. If a cylinder or two are leaking, you'll see plugs that look different from the others (from being steam cleaned by the coolant). If you find a goofy plug or two, a compression and/or leak-down test should be step 2.
If you don't lose heat, another possibility that you should start considering is that you might have a bad head gasket. A bad head gasket can both introduce air pockets into the system and consume coolant into the combustion chamber. A look at the plugs should be a good first step. If a cylinder or two are leaking, you'll see plugs that look different from the others (from being steam cleaned by the coolant). If you find a goofy plug or two, a compression and/or leak-down test should be step 2.
It has been going through fits of a few start ups and everything is fine (I drive it all day) and then it will go through a few times of not being able to get water running through the upper hose.
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Freshman User
Joined: Dec 2016
Posts: 42
Likes: 0
Check for blown head gasket(s). We have a 5.4 3-valve in our fleet that did the same exact thing. Will be fine at one point then overheat at times, even unloaded. Had the coolant system flushed, water pump, t-stat, etc all done w/OEM parts. Even changed out the cylinder head temperature sensor.
It ended up being bad head gaskets. Replaced the head gaskets and 30k miles later, she's still working hard with no issues.
It ended up being bad head gaskets. Replaced the head gaskets and 30k miles later, she's still working hard with no issues.
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Freshman User
Joined: Dec 2016
Posts: 42
Likes: 0
Resolution:
Dropped it off at the shop today.
Pressure check - ok
Block test - ok
Burped out enough air during block test to take a little over 2 gal of coolant - bingo
So that coupled with the almost 1 gal I got out of it yesterday, the system was basically half full. Now the thermostat (Motorcraft 192) is open and cooling by 198* and the truck stays 192* ish. Now I believe my troubles are over.
Dropped it off at the shop today.
Pressure check - ok
Block test - ok
Burped out enough air during block test to take a little over 2 gal of coolant - bingo
So that coupled with the almost 1 gal I got out of it yesterday, the system was basically half full. Now the thermostat (Motorcraft 192) is open and cooling by 198* and the truck stays 192* ish. Now I believe my troubles are over.
Senior User
Joined: Mar 2006
Posts: 330
Likes: 2
Resolution:
Dropped it off at the shop today.
Pressure check - ok
Block test - ok
Burped out enough air during block test to take a little over 2 gal of coolant - bingo
So that coupled with the almost 1 gal I got out of it yesterday, the system was basically half full. Now the thermostat (Motorcraft 192) is open and cooling by 198* and the truck stays 192* ish. Now I believe my troubles are over.
Dropped it off at the shop today.
Pressure check - ok
Block test - ok
Burped out enough air during block test to take a little over 2 gal of coolant - bingo
So that coupled with the almost 1 gal I got out of it yesterday, the system was basically half full. Now the thermostat (Motorcraft 192) is open and cooling by 198* and the truck stays 192* ish. Now I believe my troubles are over.
Thread Starter
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Freshman User
Joined: Dec 2016
Posts: 42
Likes: 0
SOOO
It needed the burp, but a few days later it is DOING IT AGAIN!
Take it back in they looked at for free for 2 days. Long story short, it developed a #8 misfire. Pulled the plug and it is wet from coolant. The air pockets were caused by the engine pulling in some air. The air was then collecting near the thermostat housing and preventing it from opening.
Now the fun part. I can't seem to find anyone that will fix this for less than $3,000. Is this the going rate now for head gaskets, bolts, labor, coolant, oil, resurfacing the heads etc... Seems excessive. I was hoping for between 1500 and 2k
It needed the burp, but a few days later it is DOING IT AGAIN!
Take it back in they looked at for free for 2 days. Long story short, it developed a #8 misfire. Pulled the plug and it is wet from coolant. The air pockets were caused by the engine pulling in some air. The air was then collecting near the thermostat housing and preventing it from opening.
Now the fun part. I can't seem to find anyone that will fix this for less than $3,000. Is this the going rate now for head gaskets, bolts, labor, coolant, oil, resurfacing the heads etc... Seems excessive. I was hoping for between 1500 and 2k
