99 Chrysler 300m 3.5 engine started to overheat


Asked by Aug 14, 2012 at 12:24 AM about the 1999 Chrysler 300M 4 Dr STD Sedan

Question type: Maintenance & Repair

Recently replaced thermostat water pump fans radiator an car still overheats, one day while driving
My trans cooler line had a crack in it which caused fluid to come out quickly causing the car to slip out of geAr then
had this replaced an car ran fine the next day coming from the store about5 mile drive it overheAted an reservoir
tank boiled over .  The upper hose was extremely hot to touch lower holes was cool but coolant reservoir level kept
fluctuating I was told it could be air trapped in the system that u need to bleed it  how do u bleed the system or
could it be something else causing the system to block the flow? Will air keep the system from flowing? Please
help me give me advice thanks

8 Answers


Yes trapped air in cooling system is going to reduce system effectiveness. If there is air trapped by thermostat it can fail to open. You can also blow head gaskets and crack heads with trapped air in system. These engines have a coolant system air bleed valve. One way to do this is to connect a small tube to the bleed valve, put end of tube into a container. Then add coolant until no bubbles come from tube. You will have to squeeze the upper radiator hose during this process to expel trapped air. Keep doing this until no air comes from tube and you are certain air is all out. Then make sure the coolant reservoir has plenty of fluid, run the engine up to temp, shut down the engine and let the cooling process draw coolant back into engine. You should pay attention to the level in the coolant reservoir when engine is hot and cold there should be significant difference in levels.

10 of 10 people found this helpful.

on this car the radiator is lower than engine coolant level. that's why there is a bleeder valve to right of upper radiator hose outet on top of engine.its a 10mm socket, use a 1/4 drive and socket extension. warm -op engine and use clear hose to a container to catch overflow. loosen bleeder valve and put clear hose over it. also make sure coolant recovery tank does not have any cracks or holes as it is pressurized. autozone sells one for around $40 and it comes with a new radiator cap.also there is a product called wetter water which you add to your anti-freeze,about 10 ounces to a bottle. what it does is lower the temp. of the rad. fluid by not allowing bubbles to form inside cooling system. sort of like the bubbles that cling to the side of a pot when you boil water. also at a/zone

5 of 5 people found this helpful.

most likely your radiator fans are not turning on to boil over recovery tank. make sure to turn on a/c with engine running because both fans must come on. if when you are standing in front of your car and the fan on your left is on it means the fan on right is not working and that fan is the fan that is only on when a/c is off and engine temp is over 160 degrees. if you have a bad fan look for a salvage yard that specializes in dodge parts if you can, youll have to buy both fans and shroud as a unit but youll have an extra fan for the future.

4 of 4 people found this helpful.

once you replace the radiator you HAVE TO BUY a new radiator CAP!! There is also a fan sensor that you will need to replace too that tells the fan to turn on to cool the radiator. more questions please email me at some1unv@gmail.com and put 300M in the subject please

3 of 3 people found this helpful.

thermostat in the wrong way will cause this issue, spring side goes inside the block. just a thought thanks

1 of 1 people found this helpful.

Where is the thermostat in the chrysler 300m 2000 3.5 liter

15 of 15 people found this helpful.

Hey i wrecked my 99 crysler 300 andonly hit were passenger light is fixed that then startex to over heat i just put it in shop they changed thermastat didnt over heat till half way down the street what is my issue

8 of 8 people found this helpful.

If the fans come on with the air conditioner on and they don't come with no air conditioner running then it is safe to say the fans work. It is possible the Powertrain Control Module (PCM) is malfunctioning. This over looked computer also controls your fans. Most people by this time replaced the relays because they are cheap and easy fix. If the motor does not over heat on the highway but only in traffic, this is the possible problem. Not overheating on the highway is because of motor design and generally cars today don't need a fan on the highway because of air flow across the radiator and motor is sufficient to keep the motor cool.

1 of 1 people found this helpful.

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