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Q: Engine loses power when i put radiator cap on

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I put a new radiator in after my other radiator crack and made my car over heat. Now when I start the car which takes longer then usual the engine lose power and cutoff when I put the radiator cap on but if I pull it off fast enough the engine idles back up to its normal level any ideas

My car has 200000 miles.
My car has an automatic transmission.

When you overheated the engine before when the radiator broke, you must have blown the head gasket. Have the radiator pressure tested to see if the engine cylinder gets coolant in to the cylinders. This will indicate a blown head gasket and possibly a cracked head. If you want to have this checked, a certified mechanic can come to your home or office to inspect the car’s loss of power and verify what the issue is.

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