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I changed the thermostat and coolant sensor on my mercury grand marquis 1998 its still over heating what can be the problem.

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The coolant sensor only sets some engine controls and reports to the dash gauges. A thermostat or a electric coolant fan or relay are the likely culprits.

Posted on May 01, 2015


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Posted on Jan 02, 2017

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SOURCE: my 96 meunder the mercury grand marquis is running hot

A cracked Intake manifold. Check the manifold in two places, on the front cross over behind the alternator and the base of the heater hose connector on the rear of the passenger side.

Posted on Mar 02, 2009

  • 532 Answers

SOURCE: 1998 mercury grand marquis 4.6

un-plug the coil packs--injectors--pull wiring out of the way,and then unbolt the coil packs and pull them out,and use a 6 inch to 8 inch extension on a 3/8 drive rachet with a 5/8 plug socket...snug the plugs back in pretty good because the 4.6 and 5.4 are known to blow the plugs out and wreck the threads on the head.On the drivers side you may have to unbolt the fuel rail(2 bolts)and lift it up off from the injectors,make sure that you dont tear the 0 rings on the injectors and watch to see if some or any 0 rings comes off from the injectors and stays with the fuel rail..when putting the fuel rail back on the injectors,use a little motor oil and wipe it on all 0 rings to assist in going back together without tearing the 0 rings.

Posted on May 08, 2009

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SOURCE: Change thermostat 1998 grand marquis

Locate the water hose at the top of the radiator and follow it to the top of the engine block. There you will find the thermostat housing. Remove the two bolts and remove the housing. Pay attention as to how the thermostat is sitting in the housing. Lift it out and put in the new thermostat the same way. Make sure you replace the thermostat housing gasket. Reassemble the housing and add anti-freeze until full.

Posted on Apr 11, 2010

  • 3400 Answers

SOURCE: I can turn the ac

It sounds like thermostat (in coolant system) needs to be replaced. They only control you have for temps are the dials on dash, but if coolant thermostat is sticking you're limited to what it outputs. Replace coolant thermostat and you should be "good to go"

Posted on Feb 22, 2011

  • 53 Answers

SOURCE: how do i change a thermostat in a 1996 mercury

Hi, Welcome to my name is Shawn and I will be answering your question.

  1. Partially drain the engine cooling system so that the engine coolant level is below the water thermostat (8575).
  2. Disconnect the upper radiator hose (8260) from the water hose connection (8592).
  3. Remove the two water outlet connection retaining bolts.
  4. Remove the water hose connection gasket (8255) and water thermostat from the intake manifold (9424). Inspect water hose connection gasket for damage and replace if necessary.
  1. Install the water thermostat, water hose connection gasket and water hose connection as shown.

  2. I hope my assistance helped you and resolved your concern, if you need further assistance please ask.

Posted on Aug 09, 2011

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Where on a 2003 Mercury Grand Marquis is the temperature sensor

Should be beside coolant sensor near upper hose going to radiator.

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Before you change the fan control, make sure the fan is operating. Unplug the fan and attach two wires into the fan end, one for positive and the other negative, touch both leads to the battery and insure the fan runs. Please use long enough leads so your hands are clear of any moving parts for safety

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1997 mercury grand marquis only over heat while driving

Sounds like you are due for a coolant system flush and fill and a new thermostat. I doubt the thermostat is your problem but since it's on a $7 part and the coolant system needs to be drained to change it I recommend doing so when you perform the flush and fill. Be sure you purchase either pre-mixed coolant or mix undiluted coolant with distilled water at a 50/50 ratio.

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Feb 28, 2012 | 1998 Mercury Grand Marquis

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My 98 grand marquis keeps overheating i have changed mt intake manifold,thermostat and radiator my car will overheat to the fullest and then all my antifreeze will leak out

Hello, By doing RR most of this doesn't work. What you really is a auto technician to run some test on you car. The one test they really need to do is a pressure test on the coolant system on this Mercury GM. This pressure test will indicate if there is a leak down. That is, coolant is leaking. With coolant leaking a a closed pressurized system isn't best thing for these modern vehicles.

The coolant system is a closed system and the manufactures designed the system to hold pressure above 240 degrees. By raising the boiling point by pressurize coolant system.
This helps pollution system to operate more efficiently. GB...stewbison

Sep 09, 2011 | 1998 Mercury Grand Marquis

1 Answer

I can turn the ac off and turn the heat on in my 1998 Mercury Grand Marquis. How do I control the thermostat? I have tried putting on auto,vent,floor/defrost,defrost, and turned the temp up to 90 and it...

It sounds like thermostat (in coolant system) needs to be replaced. They only control you have for temps are the dials on dash, but if coolant thermostat is sticking you're limited to what it outputs. Replace coolant thermostat and you should be "good to go"

Feb 22, 2011 | 1998 Mercury Grand Marquis

1 Answer

No heat in my 1998 mercury grand marquis

1. the thermostat may be locked up.
2. the heater in the dash may be burnt.
3. the relay may be bad.
now go and have this 3 things checked out.

Apr 28, 2010 | 1998 Mercury Grand Marquis

1 Answer

'95 mercury grand marquis enviro unit will not send heat. Fan ,ac,and breakers all good.

might be your thermostat, also make sure the fluid level is correct. it only takes a small amount of low coolant to drop the heat.

Nov 27, 2008 | 1995 Mercury Grand Marquis

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