Where is the thermostat? - 1993 Audi 90

drain coolant until its below the thermostat.then remove two thermostat housing bolts.remove thermostat housing and thermostat.make note position of thermostat before removing it.then carefully clean all old gasket material from thermostat housing and cylinder block you can buy can gasket remover at any auto parts stores.buy new thermostat gasket.if you have the paper type you need to buy RTV SILICONE to help seal gasket if you have rubber type gasket you dont need RTV SILICONE.make sure both surfaces are clean.then install new thermostat and new gasket.if you have paper type gasket apply thin 1/16 coat RTV SILICONE both sides thermostat gasket.then install gasket to thermostat housing then install housing to cylinder block first make sure new thermostat in place before installing thermostat housing. let RTV silicone sit up about hour before adding coolant.IF THERMOSTAT HAS THE O RING SEAL DONT NEED RTV SILICONE AND THE PAPER GASKET.

Trace the upper radiator hose to the mounting area on the intake manifold. Loosen the hose clamp on the manifold end of the hose and remove the hose. Pull the thermostat out of the intake manifold.

For more help and troubleshooting go through the help links below:---

Click the link below:-----

THERMOSTAT REMOVAL PROCEDURE/LOCATION DETAILS

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Where is Thermostat Located on Saturn

http://technoanswers.blogspot.com/2012/11/where-is-thermostat-located-on-saturn.html

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2004 Dodge Intrepid: How to replace Thermostat?

http://schematicsdiagram.blogspot.in/2012/06/2004-dodge-intrepid-how-to-replace.html

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How to Replace Thermostat on Audi A4?

http://repairhelpcenter.blogspot.com/2011/11/how-to-replace-thermostat-on-audi-a4.html

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How to replace Thermostat on Acura Car models?

http://repairhelpcenter.blogspot.com/2011/11/how-to-replace-thermostat-on-acura-car.html

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Where is thermostat located on 2006 dodge magnum 3.5L?//

http://repairhelpcenter.blogspot.com/2011/10/where-is-thermostat-located-on-2006.html

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Thermostat on AUDI 1.9 TDI?

http://repairhelpcenter.blogspot.com/2011/10/thermostat-on-audi-19-tdi.html

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How to replace Radiator on Audi and VW car models?

http://repairhelpcenter.blogspot.com/2011/11/how-to-replace-radiator-on-audi-and-vw.html

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How to Replace a Thermostat.

http://schematicsdiagram.blogspot.com/2011/07/how-to-replace-thermostat.html

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How to locate Thermostat on Any car model?

http://schematicsdiagram.blogspot.com/2011/12/how-to-locate-thermostat-on-any-car.html

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Where is thermostat on Audi A6?

http://technoanswers.blogspot.com/2011/12/where-is-thermostat-on-audi-a6.html

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How to replace thermostat on 1992 Buick century?

http://technoanswers.blogspot.com/2011/12/how-to-replace-thermostat-on-1992-buick.html

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Replacing thermostat on 1999 Mercury Cougar?

http://technoanswers.blogspot.com/2011/12/replacing-thermostat-on-1999-mercury.html

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Thermostat Replacement on Toyota Corolla?

http://technoanswers.blogspot.com/2011/12/thermostat-replacement-on-toyota.html

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Where is thermostat located on 2005 Dodge neon?

http://schematicsdiagram.blogspot.in/2012/02/where-is-thermostat-located-on-2005.html
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These will help.
Thanks.

Not sure if you have the 2.7L or the 3.5L so I'll post for both sizes for you:


2.7L Removal procedures

1. Drain cooling system.
   
2. Remove radiator lower hose from thermostat housing.
   
3. Remove nuts from heater tube flange studs.
   
4. Loosen starter bolt at heater tube bracket.
   
5. Pull heater tube out of thermostat housing and position out of the way.
   
6. Remove bolt and two studs.
   
7. Remove thermostat housing, O-ring and thermostat.
   
8. Remove thermostat housing bolts.
   

3.5L Removal procedures

1. Drain cooling system.
   
2. Raise vehicle on hoist.
   
3. Disconnect electrical connectors from engine oil and power steering pressure switches.
   
4. Disconnect radiator and heater hoses from thermostat housing.
   
5. Remove thermostat housing bolts.
   
6. Remove housing, thermostat, and gasket.
   

NOTE:
The OEM thermostat is staked in place at the factory. To ensure proper seating of replacement thermostat, carefully remove the bulged metal from the thermostat housing using a suitable hand held grinder. It is not necessary to restake the replacement thermostat into the thermostat housing

Thermostat Removal & Installation 2.2L Engine 2004-2005 To Remove:

1. Drain the cooling system.
   
2. Remove the thermostat housing-to-water pump feed pipe bolts.
   
3. Remove the water pump feed pipe from the thermostat housing .
4. Remove the thermostat from the housing.

To Install:

1. Install the thermostat on the housing.
2. Install the water pump feed pipe on the thermostat housing with the mounting bolts. Tighten 89 in-lb (10 Nm).
3. Fill the cooling system.

2006-2007 To Remove:

1. Drain the cooling system.
2. Disconnect the radiator outlet hose from the surge tank and thermostat housing cover. Thermostat & cover
   
3. Remove the mounting bolts and remove the thermostat housing cover.
4. Remove the thermostat from the housing. Discard the O-ring.

To Install:

1. Using a new O-ring, install the thermostat on the housing.
2. Install the thermostat housing cover with the mounting bolts. Tighten 89 in-lb (10 Nm).
3. Connect the radiator outlet hose to the surge tank and thermostat housing cover.
4. Fill the cooling system.

3.5L Engine (LZ4) W/ Variable Valve Timing & 3.9L Engine To Remove:

1. Drain the cooling system.
2. Remove the air cleaner outlet duct.
3. Disconnect the radiator outlet hose from the thermostat housing. Thermostat 3.9L
   
4. Remove the mounting bolt/stud and remove the thermostat housing.
5. Remove the thermostat from the engine.
6. Clean the sealing surfaces.

To Install:

1. Using a new gasket, install the thermostat on the engine.
2. Install the thermostat housing with the mounting bolts. Tighten 89 in-lb (10 Nm).
3. Connect the radiator outlet hose to the thermostat housing.
4. Install the air cleaner outlet duct.
5. Fill the cooling system.
6. Check the cooling system for leaks.

3.5L Engine (LX9) W/O Variable Valve Timing To Remove:

1. Drain the coolant.
2. Disconnect the radiator hose from the thermostat housing. Thermostat 3.5L
   
3. Remove the mounting bolt/stud and remove the thermostat housing.
4. Remove the housing gasket.
5. Remove the thermostat.
6. Clean the mating surfaces.

To Install:

1. Install the thermostat on the engine.
2. Install the thermostat housing and gasket with the mounting bolts. Tighten 18 ft-lb (25 Nm).
3. Connect the radiator hose to the thermostat housing.
4. Fill the cooling system.
5. Check the cooling system for leaks.

JUST DRAIN COOLANT LEVEL BELOW THE THERMOSTAT. CATCH COOLANT IN A DRAIN PAN UNDER RADIATOR.THEN REMOVE RADIATOR HOSE FROM THERMOSTAT HOUSING ON THE CYLINDER BLOCK.THEN REMOVE THERMOSTAT HOUSING AND THERMOSTAT.CLEAN THERMOSTAT HOUSING SURFACE AND THERMOSTAT HOUSING SEALING SURFACE ON CYLINDER HEAD.INSTALL NEW THERMOSTAT IN PLACE,MAKE SURE THERMOSTAT AIR BLEED HOLE FACING LEFT SIDE UPWARD ON THE ENGINE.SOME THERMOSTAT HAS TOP STAMPED ON IT.MEANING MUST BE FACING UP.WHEN THERMOSTAT IN PLACE.TAKE NEW THERMOSTAT GASKET.PUT SEALER ON BOTH SIDES OF GASKET.THEN.PUT GASKET ON THERMOSTAT HOUSING.THEN PUT HOUSING IN PLACE TORQUE HOUSING BOLTS 16 - 20 FT LBS.WAIT 1 HOUR UNTIL GASKET SEALER CURE.THEN FILL UP COOLANT SYSTEM.BLEED COOLANT SYSTEM AND CHECK FOR LEAKS.

drain out coolant in a drain until below thermostat level follow radiator hose to engine cylinder block to thermostat housing.remove thermostat housing than remove thermostat.replace with a new o-ring on thermostat before installing new thermostat.make sure thermostat housing surface and engine block surface clean.before installing new thermostat.

It is in the rear of the engine by the firewall and the intake manifold will need to be removed to gain access t it.

Engine Coolant Thermostat Replacement (LA3, LY9) Removal Procedure

1. Remove the thermostat housing. Refer to Engine Coolant Thermostat Housing Replacement .




2. Complete the following in order to remove the thermostat from the thermostat housing:
2.1. Depress the ears on both sides of the thermostat. 2.2. Rotate the thermostat until it clears the retaining feature of the housing. 2.3. Release the pressure from the thermostat. 2.4. Pull the thermostat from the thermostat housing.

Installation Procedure

1. Complete the following in order to Install the thermostat into the thermostat housing:
1.1. Align the thermostat pin to the thermostat housing orifice. 1.2. Depress the ears on both sides of the thermostat. 1.3. Rotate the thermostat until it aligns with the retaining feature of the housing. 1.4. Release the pressure from the thermostat.
2. Install the thermostat housing. Refer to Engine Coolant Thermostat Housing Replacement .

Please choose the correct steps for the size of engine that you have:

4.5L & 4.9L Engines

1. Drain the coolant to a level below the thermostat housing.
   
2. It may be necessary to remove the upper air filter assembly on some models.
   
3. Remove the 2 bolts securing the upper thermostat housing to the lower housing.
   
4. Remove the upper thermostat housing.
   
5. Remove the thermostat and O-ring from the lower housing.
   

Thermostat installation—4.5L and 4.9L engines

To install:

1. Install the thermostat and a new O-ring to the lower housing.
   
2. Install the upper thermostat housing to the lower housing. Tighten the thermostat housing bolts to 20 ft. lbs. (27 Nm).
   
3. Refill the cooling system using a 50/50 mixture of water and ethylene glycol antifreeze.
   
4. Start the engine and check for coolant leaks. Allow the engine to come to normal operating temperature. Recheck for coolant leaks.
   

4.6L Engines

1. Drain the coolant to a level below the thermostat housing.
   
2. On some vehicles, access is easier if the front-end beauty panel and the air cleaner are removed.
   
3. Remove the 2 bolts securing the thermostat housing to the intake manifold.
   
4. Remove the thermostat housing.
   
5. Remove the thermostat and O-ring from the housing.
   

Thermostat installation—4.6L Engine



Loosen the upper radiator hose clamp at the thermostat housing



Remove the upper radiator hose clamp from the thermostat housing



Remove the thermostat housing retaining bolts and . . .






. . . remove the thermostat housing from the engine



Separate the thermostat from the housing

To install:

1. Install the thermostat and new O-ring to the housing.
   
2. Install the thermostat housing to the intake manifold. Tighten the thermostat housing bolts to 18 ft. lbs. (25 Nm).
   
3. Refill the cooling system using a 50/50 mixture of water and ethylene glycol antifreeze.
   
4. Install the air cleaner and beauty panel, if removed.
   
5. Start the engine and check for coolant leaks. Allow the engine to come to normal operating temperature. Recheck for coolant leaks.
   

2001 Chevrolet Truck Venture FWD 3.4L SFI 6cyl

Removal & Installation

1. Remove the air cleaner and duct assembly.
2. Drain the coolant until the coolant level is below the thermostat.
3. Remove the crossover exhaust pipe.
4. Remove the radiator hose from the thermostat housing.
5. Remove the thermostat housing bolts and clean any sealer from the bolt threads.
   
   
   Fig. Remove the housing bolts
   
6. Remove the thermostat housing and gasket.
7. Remove the thermostat.
8. Clean the mating surfaces.

To install:




Fig. The removal and installation of the thermostat

1. Install the thermostat.
2. Install the thermostat housing and gasket.
   NOTE Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
3. Install the thermostat housing bolts and tighten them to 18 ft. lbs. (25 Nm).
4. Install the radiator hose to the thermostat housing.
5. Install the crossover exhaust pipe.
6. Install the air cleaner and duct assembly.
7. Fill the cooling system.

3.5L Engine

1. Before servicing the vehicle, refer to the Precautions Section.
2. Remove the air cleaner intake duct.
3. Partially drain the cooling system.
4. Remove the radiator inlet hose from the thermostat housing.
5. Remove the thermostat housing bolts.
6. Remove the thermostat.
7. Clean and inspect the thermostat housing gasket mating surfaces.

To install:

1. Install the thermostat.
2. Install the thermostat housing.
3. Install the thermostat housing bolts and tighten to 18 ft. lbs. (25 Nm).
4. Install the radiator inlet hose to the thermostat housing.
5. Install the air cleaner intake duct.
6. Fill the cooling system.
7. Start the engine and check for leaks.

3.9L Engine

1. Before servicing the vehicle, refer to the Precautions Section.
2. Drain the cooling system.
3. Release the tension on the hose clamp at the thermostat housing and remove coolant hose.
4. Remove the thermostat housing mounting bolts and remove the thermostat housing.
   
   
   Fig. Remove the thermostat housing to access the thermostat-3.9L engine shown
5. Remove the thermostat.

To install:

1. Install the thermostat.
2. Install the thermostat housing and tighten the bolts to 18 ft. lbs. (25 Nm).
3. Install the coolant hose to the thermostat housing and install the hose clamp.
4. Refill the cooling system to the correct level.
5. Start the engine and check for leaks.

I hope help you whit thie (remember rated this help) Have a nice day and good luck.

1. Drain the coolant to a level below the thermostat housing.
2. On some vehicles, access is easier if the front-end beauty panel and the air cleaner are removed.
3. Remove the 2 bolts securing the thermostat housing to the intake manifold.
4. Remove the thermostat housing.
5. Remove the thermostat and O-ring from the housing.

Thermostat installation—4.6L Engine Loosen the upper radiator hose clamp at the thermostat housing Remove the upper radiator hose clamp from the thermostat housing Remove the thermostat housing retaining bolts and . . . . . . remove the thermostat housing from the engine Separate the thermostat from the housing To install:

1. Install the thermostat and new O-ring to the housing.
2. Install the thermostat housing to the intake manifold. Tighten the thermostat housing bolts to 18 ft. lbs. (25 Nm).
3. Refill the cooling system using a 50/50 mixture of water and ethylene glycol antifreeze.
4. Install the air cleaner and beauty panel, if removed.
5. Start the engine and check for coolant leaks. Allow the engine to come to normal operating temperature. Recheck for coolant leaks.