Motor runs hot and looses coolant 1991 Isuzu Trooper

1991 Isuzu Trooper

Motor runs hot

My motor runs hot and looses coolant at about 2 quarts a week. I see no puddle of coolant underneath or any where. I’ve had the radiator, pressure cap and thermostat replaced. It starts fine cold but when hot, it doesn’t start up quickly but it does start, almost every time.

Most likely scenario is the engine has a blown head gasket.

You can rule out an external leak by using a pressure tester tool and pressure testing the cooling system. This will allow you to see if the leak is external or internal. Since you are pressure testing you can remove the spark plugs to see if coolant comes out the holes.

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How to pressure test the cooling system

  1. Top off cooling system radiator and overflow when engine is COLD
  2. Attach pressure tester and build pressure to radiator cap limit (usually between 15-17 lbs will do)
  3. Let stand under pressure and observe any external leaks
  4. If no external leaks are found but pressure is still dropping, Re-leave pressure from tester and remove spark plugs.
  5. Build pressure back up and observe spark plugs holes for coolant coming out.

1 thought on “Motor runs hot and looses coolant 1991 Isuzu Trooper”

  1. My mechanic found that it was not the head gasket. He found that the coolant leak was from a faulty timing chain cover gasket. The repair cost will be about the same

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