What gives?
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What gives?
So I thought I had this overheating thing figured out. New water pump, new coolant after the flush but it still does it every now and then. Here's an example. So I drive it 80 miles one direction, hunt all day and drive it 80 miles back. Round trip, about 200 miles for the day and everything was fine. I monitor the temps from the OBDII and the hottest it got was from a cold start at 212 and then hovered around 194-196 the rest of the day. It would go up to 198-200 occasionally and come right back down.
Today I go to drive it, and it heats up to 230 and still hasn't opened. No heat. What gives, NOTHING HAS CHANGED!! Then all of the sudden, I see it drinking the reservoir like crazy and all is good again. Heat and all!
I have heard, from here and elsewhere, that only the Motorcraft thermostat is reliable in these trucks. Mine doesn't have a motorcraft in it now (Stant Superstat) It has also had one in it from Oreilly. Both were 195 degree. Is there really something up with the thermostat or something else?
Today I go to drive it, and it heats up to 230 and still hasn't opened. No heat. What gives, NOTHING HAS CHANGED!! Then all of the sudden, I see it drinking the reservoir like crazy and all is good again. Heat and all!
I have heard, from here and elsewhere, that only the Motorcraft thermostat is reliable in these trucks. Mine doesn't have a motorcraft in it now (Stant Superstat) It has also had one in it from Oreilly. Both were 195 degree. Is there really something up with the thermostat or something else?
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Since you have 2 thermostats, I assume you have a 6.4 +. It might be air trapped in your system. If you don't purge all the air after you changed the pump and refilled the coolant, you will have air pockets. When that air pocket moved to your heater core, then no heat. Air pockets will cause heat spikes in different parts of the motor. When all of a sudden, you see it drinking coolant like crazy and then everything ok again, I would say it finally burped out that air and the coolant level dropped when it filled the air pocket. This is just my opinion and theory that follows the pattern that you mentioned.
After you open up the system when replacing the pump, you need to refill the coolant with a vacuum method. If not. it might take a real long time to purge, and imo, you would have to run with the pressure cap slightly loose to allow air to escape before finally tightening it down.
Last time I refilled a 6.4 without using a vacuum, It took 2 weeks of driving with the cap slightly loose and 2 additional gallons of coolant before the coolant level stabilized.
After you open up the system when replacing the pump, you need to refill the coolant with a vacuum method. If not. it might take a real long time to purge, and imo, you would have to run with the pressure cap slightly loose to allow air to escape before finally tightening it down.
Last time I refilled a 6.4 without using a vacuum, It took 2 weeks of driving with the cap slightly loose and 2 additional gallons of coolant before the coolant level stabilized.
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Joined: Mar 2006
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Since you have 2 thermostats, I assume you have a 6.4 +. It might be air trapped in your system. If you don't purge all the air after you changed the pump and refilled the coolant, you will have air pockets. When that air pocket moved to your heater core, then no heat. Air pockets will cause heat spikes in different parts of the motor. When all of a sudden, you see it drinking coolant like crazy and then everything ok again, I would say it finally burped out that air and the coolant level dropped when it filled the air pocket. This is just my opinion and theory that follows the pattern that you mentioned.
After you open up the system when replacing the pump, you need to refill the coolant with a vacuum method. If not. it might take a real long time to purge, and imo, you would have to run with the pressure cap slightly loose to allow air to escape before finally tightening it down.
Last time I refilled a 6.4 without using a vacuum, It took 2 weeks of driving with the cap slightly loose and 2 additional gallons of coolant before the coolant level stabilized.
After you open up the system when replacing the pump, you need to refill the coolant with a vacuum method. If not. it might take a real long time to purge, and imo, you would have to run with the pressure cap slightly loose to allow air to escape before finally tightening it down.
Last time I refilled a 6.4 without using a vacuum, It took 2 weeks of driving with the cap slightly loose and 2 additional gallons of coolant before the coolant level stabilized.
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Res cap is about 3 days old. Motorcraft. Guess all that is left is a Motorcraft thermostat. It is interesting, because since I've been monitoring the temps, some times it will open and begin going down by 204. Other times it is more like 208-216. Then today it didn't open. Shouldn't these things start to open before then?
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Joined: Jul 2015
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From: very South Texas
Motorcraft thermostat..
what about fan housing. and side seals to radiator???
and air pockets can be a real PAIN to remove.
what about fan housing. and side seals to radiator???
and air pockets can be a real PAIN to remove.
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I should also add that as the engine warms up, the coolant level rises, which is what I would expect to happen. However, when the temperature gets too high because the thermostat doesn't open (or something?) it will start to come out of the cap. Not a lot, but then the thermostat opens and the level drops and stays there. Once that happens, it will run all day.
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The reason why I really think your problem is air, is because your heater stopped working. Classic sign of air pocket working into the heater core. Then you say it suddenly drank coolant and everything stabilized. That tells me the air purged and the void was filled by coolant (assuming the coolant was not lost and just displaced)
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Might as well change your thermostat anyway. You can check your old thermo after you take it out. Take a pot of water and put it on your stove. Place the thermo in it and as the water starts heating up, you will see the thermostat open if its working correctly. If you have a thermometer or a temperature gun, you can hold that in the water and the moment the thermo opens, read the temp. that will tell you when and if the thermostat is working correctly.
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I'm not losing coolant, as the level remains steady. I just don't understand the day to day intermittent problems. Could the system act normal one day and then all of the sudden have an air pocket causing the problems I am having (assuming I am not removing any hoses, clamps, caps etc...)? This is the part that I don't understand. Is the pocket just moving around but every now and then it gets in a spot that causes issues?