Question about 2000 Pontiac Grand Prix

1 Answer

How to you replace the thermostat in a 3.1l gm engine

Posted by on


1 Answer

  • Level 1:

    An expert who has achieved level 1.


    An expert whose answer got voted for 2 times.

  • Contributor
  • 1 Answer

3.1 Thermostat replace
You'll want some pretty good lighting. If you were thinking of investing in some shop lights for your garage,now would be a good time.

Tools required from memory:
1. 13 MM, 12 point, box end wrench for lowerthermostat housing bolt
2. 3/8 rachet 3. 3/8 drive 13 MM wobble socketor 13 MM short socket with universal joint for upper thermostat housing bolt. 4. 3/8 drive 6" extension 5. 9/32" socket or endwrench for bleeder screws
6. Channel Lock to release hose clamps. Also a normal pliers for the small clamps ifyou use Method 1.
7. Siphon tube
8. Container to capture antifreeze
9. Latex gloves

1. Let the car cool down.
2. Siphon about a gallon ofantifreeze from the radiator. 3. Follow the top radiatorhose on the driver's side to the engine and remove the hose from the thermostathousing. The thermostat is under thethermostat housing. There is no gasketbecause the thermostat has a rubber ring built onto it. 4. Remove the rigid PCVintake hose from air inlet duct
5. Loosen the air inlet duct clamps onthe air cleaner and throttle body, and move the duct aside. This is a perfect time to check the aircleaner element and clean the housing of debris. 6. There are couple of methodsyou can use to remove the thermostat housing. Method 1. Remove the throttle body. You will need a new throttle body gasket butit makes getting at the lower thermostat housing bolt easier. You will also need to remove the littlecoolant hoses that feed the throttle body. It does give you the opportunity to clean the throttle body withcarburetor cleaner if you wish. Thismethod requires no more explanation since the thermostat housing lower boltwill be fairly accessible. Method 2. Do not remove the throttle body. You will not need any parts other than thethermostat, but you have very little room to move your wrench on the bottom thermostathousing bolt, which makes it slow going. It generally requires you to remove one coolant line from the heatercore where it connects to the steel tube by the throttle body in order to getthe lower bolt back in, depending on the length of your fingers. a. Optionally, remove the heater hose that runsto the metal tube near the throttle body. You can get the lower bolt out without this step. The problem I have without this step isgetting the lower bolt back in.
b. Remove the lower bolt first. Youwill need to maneuver your hands both under the exhaust manifold on the frontside and from behind the exhaust manifold on the back side to move the 13 MM boxend wrench 30 degrees at a time. This iswhy you need a 12 point box end. Youcould try the ratcheting box end wrench, but when it starts to get loose, it'stough to put enough friction on it for the ratchet to work. You will hear people talk about how thehosing is slotted so you don't need to remove it all the way. That is false. That only works on old 3.1s that have a longstud and nut. You cannot remove thethermostat housing without removing the bolt because the thermostat extendsinto the thermostat housing for longer than the bolt. (Been there, tried that.)
7. Remove the upper bolt with the 13 MMsocket, universal joint, extension, and ratchet. 8. Clean the face of thethermostat housing and recess there the thermostat fits into the inlet manifoldin the thermostat rubber seal contact area.
9. Insert the new thermostat goes intothe inlet manifold, spring end first. Make sure it is in all the way so the rubber ring does not get pinchedwhen you tighten the thermostat housing down on top of it.
10. Replace the thermostat housing.11. Usingthe 9/32" wrench or socket, open the bleeders on the thermostat housing andwater pump. The water pump is located onthe passenger side on the front of the engine on the steel water manifold.
12. Pour as much antifreeze as will fitinto the radiator.
13. Start the engine to bring it up totemperature, and turn on the heater.
14. While it's running, watch the bleeders. When antifreeze starts to come out of ableeder, close that bleeder.
15. When the thermostat opens, the levelin the radiator will drop and you will be able to pour in most of the the remainderof the anti-freeze. Then replace the cap. Pour the little remaining into the reservoir.

Posted on Nov 29, 2010

  • JToering Nov 29, 2010

    The missing spaces causing run-on words, and missing carriage returns resulting sequence numbers in the middle of paragraphs in the above procedure were not in the original text, but caused by the site software when posted to this forum. Moreover, bold and underline formatting was also removed during the post process.

  • blueharpri Jan 21, 2011

    Thank you for your accurate description of the process. I previously checked the situation out and came up with just what you descibed. now I feel confident in proceeding. I always wondered the proper bleeding process. Now I know! Thanks again for your help.

    Tim M.



1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of.(from cars to computers, handyman, and even drones)
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

My car says engine hot A/C off

If the engine overheats, the computer will turn the ac off. However, on GM vehicles, the thermostat can be bad, not letting the engine get warm enough, and causing the same problem. I would replace the thermostat.

Feb 12, 2015 | 2009 Pontiac Torrent

3 Answers

2007 equinox as soon as i start my car is said engine hot ac off ,but car is not hot someone help

You need a new thermostat in your engine now if your getting sluggish engine performance and its over heating you might have a blown head gasket and hello 2 grand mechanic bill :(

Dec 30, 2014 | Cars & Trucks

1 Answer

How to change thermostat in 2009 Saturn Outlook?

follow the hose from raidiator on top back to bellhousing take that off thermostat

Feb 18, 2014 | 2009 Saturn Outlook

1 Answer

How do you replace 2001 dodge caravan heater switch?

To replace a thermostat in a 2001 Dodge Grand Caravan, look at the engine. Should be located at the engine end of the upper radiator hose in removable housing. Drain about 1 gallon of coolant from radiator Remove housing - make note how thermostat is installed Clean both surfaces Install new thermostat and gasket Re-fill coolant slowly to prevent an "air lock" Start engine check for leaks Run engine to normal operating temperature with heater on Check coolant level.------------------------------------------------------------------------------------
card for gm tech2

Jan 05, 2013 | Cars & Trucks

1 Answer

My tempature gauge will register normal tempature after engine runs and heats up but will drop back to no tempature.

ZI suggest you have the engine thermostat replaced, it is likely sticking open and allowing the engine to cool down. The thermostat is under the cover that the upper radiator hose connects to on most GM engines.

Jul 24, 2012 | 2005 Chevrolet Silverado

3 Answers

Just flushed rad heater core and block because i had no heat. flushed the system filled with new antifreeze. my temp gauge will change from 150 to 210 I have heat then i dont

Replace the thermostat. I have had bad luck with aftermarket thermostats on this particular year of GM/ Chevy trucks.They tend to stick closed and then fully open, thus causing the temp to sort of surge hot and cold. A good thermostat will slowly open maintaning a good consistant temp. I would recommend spending a little more and getting a GM thermostat.

Please take a moment and rate my answer..........Thanks

Dec 01, 2010 | 1996 GMC Jimmy

1 Answer

Replace thermostat on 97 cavalier?

GM Cavalier/Sunfire 1995-2000 Repair Guide


2.2L Engine
(see Figures 1, 2, 3, 4, 5 and 6)

0900c1528003cd07.jpg Fig. 1: The thermostat is located in the lower radiator hose on the 2.2L engine

0900c1528003cd08.jpg Fig. 2: Remove the two retaining bolts for on the housing

0900c1528003cd09.jpg Fig. 3: Separate the housing halves to access the thermostat

0900c1528003cd0a.jpg Fig. 4: Pull the thermostat out to remove it from the housing

0900c1528003cd0b.jpg Fig. 5: The thermostat has an O-ring which goes around the center

0900c1528003cd0c.jpg Fig. 6: Thoroughly clean the mating surfaces of the thermostat housing
When adding coolant, it is important that you use GM Goodwrench DEX-COOL® (orange colored, silicate free) coolant meeting GM specifications. On these vehicles, if silicated coolant is added to the system, premature engine, heater core or radiator corrosion may result. In addition, the engine coolant will require change sooner; at 30,000 miles or 24 months.
  1. Disconnect the negative battery cable.
  2. Properly drain and recover the coolant until the level is below the thermostat.
  3. Unfasten the coolant outlet-to-inlet manifold attaching bolt and nut, then remove the outlet.
  4. Remove the thermostat. Clean the inlet manifold and outlet mating surfaces.

To install:
  1. Install a new O-ring onto the thermostat
  2. Place the thermostat in the inlet manifold.
  3. Attach the coolant outlet to the inlet manifold, using the bolt and nut. Tighten to 89 inch lbs. (10 Nm).
  4. Refill the engine cooling system.
  5. Connect the negative battery cable, then start the engine and check for coolant leaks.

Hope this helped (remember comment and rated this).

Apr 05, 2010 | 1997 Chevrolet Cavalier

2 Answers

Need location of thermostat ,over heating.

If you follow the top hose from the radiator to the motor you'll notice a housing where the hose meets the motor. Disconnect the hose and remove the two bolts holding the housing in place. Remove the housing and the thermostat is underneath. When you replace it make sure the old gasket is completely removed and replaced with a new one. If pieces of the old gasket remain you will nto get a good seal and will eventually end up with leaks.

Nov 14, 2009 | 1997 Chevrolet Cavalier

2 Answers

Thermostat location on 2003 L4.2 Gm engine

t-stant is on top front of engine,just follow upper radiator hose to engine and were it clamps to housing thats were t-stant is remove bolts and housing lifts.hope this helps.

Oct 09, 2009 | 2003 Chevrolet Blazer

1 Answer

Service engine soon light on 2003 Saturn Vue

Here is the definition of the code in GM manual:
P0128 - Coolant Thermostat Below Thermostat Regulating Temperature, this indicates the engine is running cold, u need a thermostat

Feb 12, 2009 | 2003 Saturn VUE

Not finding what you are looking for?
2000 Pontiac Grand Prix Logo

2,339 people viewed this question

Ask a Question

Usually answered in minutes!

Top Pontiac Experts


Level 3 Expert

76846 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22246 Answers

Jeffrey Turcotte
Jeffrey Turcotte

Level 3 Expert

8560 Answers

Are you a Pontiac Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides