DIY: Repairing a 2000 Ford Focus Thermostat

Written by tim petruccio
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DIY: Repairing a 2000 Ford Focus Thermostat
A faulty thermostat can stick shut, causing excess pressure to rupture radiator hoses. (Thinkstock/Comstock/Getty Images)

The 2000 Ford Focus is equipped with a 2.0-litre, dual-overhead cam engine. This in-line four-cylinder engine can produce 130 horsepower at 5,300 RPM. The Ford Focus replaced the Ford Escort and Mercury Tracer in 2000. The 2000 Focus was offered as an LX sedan, SE sedan, SE wagon, ZTS sedan or ZX3 hatchback, and received much attention the year it was introduced. Replacing the thermostat in a Focus is usually done to restore heat to the vehicle during cold months or to stop an engine from overheating due to a failing thermostat.

Skill level:

Things you need

  • 3/8-inch drive ratchet and socket set
  • 1-gallon or larger drain pan
  • Radiator hose pliers or long-nosed vice grips
  • New thermostat (Fail-safe recommended)
  • New thermostat gasket
  • 1-gallon 50/50 mixed coolant (standard green or universal)
  • Flat head screwdriver
  • Razor blade or box cutter
  • 1-tube Permatex gasket maker/sealer (grey tube)
  • Funnel

Show MoreHide


  1. 1

    Clamp the radiator hose shut that leads into the thermostat housing with a pair of radiator hose pliers or long-nosed vice grips. Place a dripping pan directly beneath the engine underneath the thermostat housing.

  2. 2

    Remove the two thermostat housing bolts for the thermostat housing cover with a 3/8-inch drive ratchet and socket set. Remove the thermostat housing cover to expose the thermostat. Remove the old thermostat, using a flat head screwdriver for leverage.

  3. 3

    Scrape all excess gasket material from the surfaces of the thermostat housing and the thermostat housing cover with a razor blade or box cutter. Scrape the mounting surfaces in an outward motion from the engine to avoid introducing gasket particles into the cooling system.

  4. 4

    Place a very thin coating of Permatex gasket maker/sealer between the mounting surface and the gasket for a true seal. Spread the gasket maker/sealer onto the mounting surface with your finger, leaving just a thin film on which to glue the gasket. Place the new thermostat gasket onto the thermostat housing mounting surface. Apply another very thin layer of gasket maker/sealer to the outer side of the gasket for the thermostat housing cover.

  5. 5

    Install the thermostat housing cover straight down onto the thermostat housing. Do not rotate, turn or slide the cover to avoid moving the gasket. Slide the thermostat housing bolts through the cover and start them by hand.

  6. 6

    Tighten the mounting bolts to 15 foot-pounds of torque with a 3/8-inch drive ratchet and socket.

  7. 7

    Open the radiator cap and top off the entire cooling system. Let the system stand for at least one hour to ensure that the gasket maker/sealer has cured completely.

  8. 8

    Start the engine of your Focus with the radiator cap off. Turn the temperature control switches to full heat and the selector switch to defrost. Leave the radiator pliers on the radiator hose for this step. Let the engine warm for at least 10 minutes.

  9. 9

    Remove the radiator hose pliers to allow coolant to start moving freely again through the cooling system. Watch for air bubbles to rise up and out of the radiator. Let the engine run for at least another five minutes, occasionally squeezing the radiator hose to remove any air pockets in the system.

  10. 10

    Shut the engine off and top off the radiator again with a funnel. The entire cooling system only uses 3/4-gallons of coolant. Double-check your work for any leaks or excess steam coming from the engine bay. Reinstall the radiator cap.

Tips and warnings

  • When changing the thermostat in your Focus, it is a good idea to do a complete flush or draining of the cooling system. Do this by removing the drain plug at the bottom of the radiator as well as the lower radiator hose. Let the cooling system drain into a drain pan. Reinstall the hose and drain plug. Refill the entire system with coolant by filling the radiator and completing Steps 8 through 10 above in order to remove air pockets from the system.
  • Engine coolant, or antifreeze, contains Ethylene Glycol, which is extremely poisonous to both humans and animals. Wash your hands thoroughly with soap and water for at least five minutes after physical contact with coolant.

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