Changed Anti-freeze, Now Running Hot

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Drained old stuff out via petcock on lower corner of radiator of the 2000 Ford Ranger. Didn't seem like all that much came out; book says it holds 13 quarts. Put little over 1 1/2 gal of 50-50 Green in radiator and overflow tank. Went for 10 mile drive and temp gauge topped out, but fluctuated up and down some. Never got into the red but darn close to it. Never had any issues with it before; in fact the gauge normally is down below the half mark. No sludge or unusual nastiness in the drained fluid. Does this sound like an air block? If so, what can I do about it? Have drained many vehicles this way before and never had an issue.
 
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Probably worth burping the air out again if you can. To help, turn the heater to the highest setting while pouring more coolant in. If it's easy enough, park on an incline so that the front of the vehicle is higher than the rear. Chances are, a few driving cycles will bleed the air out too, just keep an eye on the reservoir level.
 
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well, could be an air gap somewhere. Try taking the radiator cap off when the engine is cold. Place a funnel into the radiator cap area. Fill the funnel with radiator fluid so it stays vertical and in place. Start the car and let it idle till it gets to operating temp. You will see bubbles in the funnel area and keep the funnel filled as needed...after 5-10 minutes or so turn off engine, replace radiator cap and that should have bled the system well. If you STILL have issues, could be a stuck Thermostat or your radiator cap is not holding pressure. Jeff
 
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Originally Posted By: Jeffs2006EvoIX
well, could be an air gap somewhere. Try taking the radiator cap off when the engine is cold. Place a funnel into the radiator cap area. Fill the funnel with radiator fluid so it stays vertical and in place. Start the car and let it idle till it gets to operating temp. You will see bubbles in the funnel area and keep the funnel filled as needed...after 5-10 minutes or so turn off engine, replace radiator cap and that should have bled the system well. If you STILL have issues, could be a stuck Thermostat or your radiator cap is not holding pressure. Jeff
I also found that squeezing and releasing the upper radiator hose, preferably when cold, helps burp some of the air.
 
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An air block is a good possibility. Try taking car for short drive to get operating temp up and then leave runing in driveway. turn on heater. remove overflow hose, carefully remove radiator cap. Them squeeze upper and lower radiator hoses. see if there is any sign of air bubble working its way out. If that does not work, drain and refill. Drain when hot. Refill when cold, and very xlowly. start the car when half full and refill the rest. Hopefully your problem is not crud in the water pump or thermostat. good luck
 
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Did you tighten the cap back up? If it's like my 99 Bull with pressurized overflow it should burp itself but you need to let it run idle with the heater on and over flow tank cap off.
 
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Probably air in the system. Check to see if there are bleed screws and if so, use them appropriately. You may need to buy a lisle coolant funnel and use it as well.
 
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If the cap is good the system will work the trapped air out. Just check it every day before you start it and top it off. Sooner or later it will stay full.
 

tc1446

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Wow, all great answers and every one much appreciated. After coming in from the drive I did fill the overflow tank about 3/4 full and noticed a few bubbles at that time. After reading all these good replys, I went out after it had cooled, opened the radiator cap and it was really low; also the fluid in the overflow was pretty will sucked out. Added nearly another gal so I believe I'm good to go. Just never had this happen before. Learned some useful things today. Thanks to each of you.
 
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Open the Air Conditioner hot air to ensure the heater core coolant is also cycled. As mentioned above, probably an air bubble. A lislie funnel is great for those purposes.
 
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Have you checked your Owner's Manual? My 1990 Mercury Cougar V6 has a specific bleed process outlined in the manual.
 
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The exact same thing happened to me and here is why When you drain the coolant out it deains the whole system (captain obvious) but when you fill it back up again the thermostat will be closed preventing coolant getting into the block Because there is no coolant in the engine block it heats up very quickly and because there is no hot coolant to open the thermostat it will stay that way! 2 ways to solve this: manually fill the block by removing your thermostat housing and thermostat then pour through the hole Or what i did but it takes a while is to squeeze all the pipes with coolant in until you see bubbles in the radiator or resovoir and see the level declining, and just keep topping up as it does so
 
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The fluctuation is a sure sign of air trapped at the thermostat. When I install them I drill a 1/8" hole in them to let air out. With air against the paraffin that has to expand, it can't sense the real temperature. You got air in it. I always recommend after changing fluids to warm up the engine, then let it sit overnight while it sucks out the overflow reserve. Sometimes a second time.
 
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Originally Posted By: 19jacobob93
The exact same thing happened to me and here is why When you drain the coolant out it deains the whole system (captain obvious) but when you fill it back up again the thermostat will be closed preventing coolant getting into the block Because there is no coolant in the engine block it heats up very quickly and because there is no hot coolant to open the thermostat it will stay that way! 2 ways to solve this: manually fill the block by removing your thermostat housing and thermostat then pour through the hole Or what i did but it takes a while is to squeeze all the pipes with coolant in until you see bubbles in the radiator or resovoir and see the level declining, and just keep topping up as it does so
When I get this, I remove the top radiator hose from the rad when I think the system is full. Start slowly in case some might spill out-- but it typically doesn't. I stick a funnel in the hose, stretch it high over the motor, typically a foot or more, and backfill the engine through this hose. This pressure then forces coolant down to the thermostat, but also through the heater core/ bypass system, down through the radiator and up again. When it dribbles out the top nipple, things are pretty full. This works on obstinate thermostat locations (typically down low) and may not work on simple ones like the traditional one that's at the engine end of the top hose anyway.
 
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Originally Posted By: EdwardC
Probably worth burping the air out again if you can. To help, turn the heater to the highest setting while pouring more coolant in. If it's easy enough, park on an incline so that the front of the vehicle is higher than the rear. Chances are, a few driving cycles will bleed the air out too, just keep an eye on the reservoir level.
This, with radiator cap off. 1/2 hour or three thermostat cycles, whichever comes last, should do it.
 
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