3.5L Overheat

Tiny
TINO_SOCCER87
  • MEMBER
  • 2002 CHRYSLER CONCORDE
  • 6 CYL
Will my car overheat if a vaccuum leak was detected from the injectors?
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Wednesday, May 18th, 2011 AT 8:33 PM

14 Replies

Tiny
CARADIODOC
  • EXPERT
Do you mean there's a vacuum leak around the o-rings where the injectors plug into the intake manifold? That won't cause overheating but it can cause a high idle and a hesitation.
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Wednesday, May 18th, 2011 AT 10:02 PM
Tiny
TINO_SOCCER87
  • MEMBER
Okay thank you. Can you help me find out why my car overheats then? I have changed the theremostat, head gaskets, intake gasket, cooling fans, sensors, radiator, radiator hoses and my connections. Everything seems fine but when I drive for about 20 minutes it will get hot and on comes my tempurature light.
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Thursday, May 19th, 2011 AT 9:07 PM
Tiny
CARADIODOC
  • EXPERT
The head gaskets would have been my first suggestion. You might still consider having a mechanic perform a leak test at the radiator cap with a special tool.

Next wuld be to check if the radiator fan is turning on. A fast way to do that is by unplugging the two-wire coolant temperature sensor while the ignition switch is on. That should cause the fan to run. If it does not, there might be a blown fuse for the fan. The best way to diagnose it is by using the DRB3 scanner to command the fan to run.

Sorry for taking so long to reply. The site stopped working on my regular computer. Just want you to know I'm not ignoring you.
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Friday, May 20th, 2011 AT 6:22 AM
Tiny
TINO_SOCCER87
  • MEMBER
I am still having problems with the car overheating. What would make the thermostat not open? It has a new one, and then fans are working.
I have the pressure tester and I dont see any leaks. What could it be?
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Friday, May 20th, 2011 AT 11:23 PM
Tiny
TINO_SOCCER87
  • MEMBER
Would it be caused from a EGR valve or a BP valve?
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Saturday, May 21st, 2011 AT 2:53 AM
Tiny
CARADIODOC
  • EXPERT
An air pocket can prevent the thermostat from opening. Thermostats open in response to hot liquid, not hot air. You should see a bleeder screw on the thermostat housing. Be sure to open that after the thermostat was replaced.

Feel the lower radiator hose when the engine is hot. If that hose is cold, coolant isn't flowing. You might consider removing the thermostat to see if that makes a difference. If there is still no evidence of circulation, suspect a problem with the water pump. One possibility is the impeller can be worn away or it can be cracked and spinning on the shaft. Also check the tension on the timing belt since it runs the water pump. A loose belt will slip over the pump's pulley.

If you repeatedly find air coming from the bleeder screw, suspect the head gaskets are leaking. When those gaskets are replaced, the heads must be checked for cracks and for warpage. Warpage must be checked at an engine machine shop or by a mechanic who has a straightedge. The maximum allowable warpage with aluminum heads is.002" in any direction.

To check for leakage, first look for the presence of bubbles in the reservoir when the engine is running. If you see any before the engine has warmed up, suspect the head gasket. The clue is the engine isn't hot yet and there's no steam with those bubbles. Most mechanics can perform a test for you that involves a glass cylinder with two chambers partially filled with a special dark blue liquid. Air from the reservoir is drawn through that cylinder. If combustion gases are present, the liquid will turn bright yellow. Those gases will create that air pocket again that prevents the thermostat from opening.
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Saturday, May 21st, 2011 AT 4:11 AM
Tiny
TINO_SOCCER87
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Okayy thank you. Can the overheating be caused by an EGR valve, a BP valve, or a knock sensor?
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Sunday, May 22nd, 2011 AT 10:01 PM
Tiny
CARADIODOC
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Nope. The EGR valve allows exhaust gas into the engine at highway speeds only. While that gas feels hot to us, it is "inert" and takes up space so less fresh gas and air fits into the engine. That means less heat is produced in the engine and less fuel is burned.

A knock sensor picks up pinging in the engine, and in response, the Engine Computer retards ignition timing a little. In a very severe case, some of that fuel and air might finish burning in the exhaust manifold rather than in the engine. Heat from the exhaust manifolds doesn't transfer into the cooling system so it won't cause overheating.

Not sure what you mean by a "BP" valve.
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Sunday, May 22nd, 2011 AT 10:50 PM
Tiny
TINO_SOCCER87
  • MEMBER
Okay thank you, you are really helping. And I mean a bypass valve. Do you think that would cause the overheating? I am looking for other alternatives that will cause the overheating.
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Monday, May 23rd, 2011 AT 3:13 PM
Tiny
CARADIODOC
  • EXPERT
I'm not aware of a bypass valve but there is a bypass passage. That gives the coolant someplace to go while the thermostat is closed.

When the overheating occurs, feel the lower radiator hose. If it is real hot, the heat is not leaving the radiator. That can be due to air flow blockage, a fan that's not turning on, a fan that's wired wrong and blowing the wrong way, a missing shroud that lets the hot air go back around and through the radiator rather than drawing cool air in. Related to that, look for a missing rubber strip under the front edge of the hood. That is a seal that forces air through the radiator.

If the lower hose is not hot, the coolant may be not circulating properly. Check the water pump impeller and be sure the timing belt is tight and not slipping. You may have to flush the cooling system and try removing the thermostat to verify it is not sticking closed. If the coolant is not circulating, the air from the heater will not be as hot as normal.

A clue to a fan-related problem is the overheating will not occur while driving at highway speeds.
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Monday, May 23rd, 2011 AT 11:10 PM
Tiny
TINO_SOCCER87
  • MEMBER
Okay. My heater works real hot. My car is still overheating and I believe that the coolant is not circulating properly. It seems to be circulating from the heater hose to the thermostat. Can you help?
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Wednesday, May 25th, 2011 AT 3:05 AM
Tiny
CARADIODOC
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Double-check that the fan is turning on and blowing the right way. You said you replaced the radiator. Was that a new or used one? If it was used, check if the cooling fins are rotted away. That will reduce its ability to give off the heat to the air.
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Wednesday, May 25th, 2011 AT 5:20 AM
Tiny
TINO_SOCCER87
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The radiator is a new one.

I attached a picture of my water pump and the way it is rotating. Isnt it going the wrong way? What can I do about this?
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Thursday, May 26th, 2011 AT 12:17 AM
Tiny
CARADIODOC
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Nope. It's going the right way. The vanes throw the coolant outward and centrifugal force is what creates the force that makes it flow.
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Thursday, May 26th, 2011 AT 8:36 PM

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