Overheating engine

2005 DODGE MAGNUM
116,000 MILES
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WILLWELLS41
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The engine overheats and air gets into the coolant system and I cannot find a solution. To date I have had the thermostat changed three times, a new radiator was installed (that was not needed), the head gaskets have been done (only to find that was not needed), the water pump and timing belt have been changed (not sure if the water pump needed to be replaced), the problem still exists and I have had three mechanics do work on the engine to the tune of a lot of money. At idle the temperature gauge stays around the middle, under load or driving a little while the gauge goes up almost to the red. While driving and I turn the heat on in the car, the temperature gauge will go down to about 3/4. The water system boils and flows out the overflow container, both fans will kick on when hot and I am hoping the thermostat opens. There has been two pressure tests done on it and no leaks detected. As I mentioned I am in the hole for $1,700.00 so far and no change to the problem. My current mechanic is a great guy and he has put a lot of his own time into this repair as well and he feels bad that he cannot solve the problem. Any ideas as to what the mechanics may have missed?
Jul 10, 2013 at 7:48 AM
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DOCFIXIT
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Cooling system air bleeding procedure followed? If so I would chemical check the engine again because it sounds like you have a cracked head or engine block because air/exhaust keeps getting into the system making the engine overheat. Here are two guides that can help:

https://youtu.be/5zpNjYmmiYY

and

https://www.2carpros.com/articles/engine-overheating-or-running-hot

Check out the diagrams (below). Please let us know what happens.

Cheers
Jul 10, 2013 at 8:04 AM
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WILLWELLS41
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Yes, it was and still no results.
Jul 11, 2013 at 7:54 AM
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DOCFIXIT
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The chemical test is only about 75% accurate so it might still be a cranked head/block. Do the cooling fans work at two speeds make sure they go to high speed?
Jul 11, 2013 at 8:57 AM
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WILLWELLS41
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It is the 3.5 L engine and yes the fans work fine. I am currently considering taking it down again and sending heads to the machine shop.
Jul 11, 2013 at 9:39 AM
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DOCFIXIT
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Make sure fans have two speeds just coming on will not cool enough need to go to higher speed that is why when heater is on temperature drops. Before pulling heads have a block test done for presence of CO in coolant. Can get a test kit at NAPA. If no CO then heads are okay.
Jul 11, 2013 at 11:15 AM
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BRE209
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I had this problem as well, the block has cracked I had to get a new engine. :( Cost me $3,800.00. Wow!
Nov 1, 2015 at 1:59 PM
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COUNTRYM49
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Overheating fans will not turn on. What do I do?
Aug 29, 2018 at 3:17 PM (Merged)
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ERNEST CLARK
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First check fan relay. If good, apply direct voltage to the fan motors to see if they work. If they do not, replace them. If they do, check ECT sensor and wiring/connector.
Aug 29, 2018 at 3:17 PM (Merged)
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VINCENT LACY
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Car just started overheating, turned A/C on and when I turned it off car started getting hot.
Aug 29, 2018 at 3:17 PM (Merged)
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WRENCHTECH
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The first step is to pressure test the cooling system for leaks. If system holds pressure and shows no sign of leaks, then verify fan operation.
Aug 29, 2018 at 3:17 PM (Merged)
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KRISTY80
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I have a 2006 3.5L Dodge Magnum. The car started overheating about a month ago. We went and tested the radiator cap at AutoZone and they said it was not holding pressure, so we bought a new cap. The car has been not overheating for about 2-3 weeks now. Yesterday the car overheats. So I checked the coolant and it was empty. I filled it up last night and have not drove the car since then. I just went out to check the coolant level and it was empty again. Where is all this coolant going? Because it is not leaking into the oil and it is not leaking on the ground. Can you help me figure this out?
Aug 29, 2018 at 3:17 PM (Merged)
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MHPAUTOS
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You will have a small external coolant leak, under pressure it may be dripping onto the exhaust, get the system pressure tested as this will help locate the leak.
Aug 29, 2018 at 3:17 PM (Merged)
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ASEMASTER6371
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take it to a shop and have them insert a dye and then they will pressure test it and the leak will show under a ultra violet light.

Roy
Aug 29, 2018 at 3:17 PM (Merged)
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SWEETS2580
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Hello, my car is overheating, i have changed the thermostat and hose. It only stays cool when i run the heat. Should i stop using half and half coolant and i pouring water in there as well? Should i use straight coolant no water added?
Aug 29, 2018 at 3:17 PM (Merged)
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MHPAUTOS
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Need to investigate other things first, it sounds like an air flow problem, make sure that the cooling fans are working, there is no rubbish built up between the radiator and the air conditioner condenser blocking air flow, and the radiator is flowing and not pat blocked, this is hard to tell with out removing and having it core cleaned by a radiator specialist.
Aug 29, 2018 at 3:17 PM (Merged)