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Thread: Antifreeze & o2 Sensor Damage-Cracked Heads

  1. #1
    Advanced Tuner 2therock's Avatar
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    Antifreeze & o2 Sensor Damage-Cracked Heads

    I have heard that burning antifreeze will damage o2 sensors.

    Problem = bad gas mpg after heads replaced.

    We have a reg cab 04 Silverado w/5.3 that the water pump went out on, got hot and the heads cracked.

    They were a small enough cracks the antifreeze would consume at a quart a day or so. No smoke but stinky.

    This went on for weeks while while we fought with the extended warranty Co for coverage. Long story but we got them to cover it.

    The o2 sensors were not considered by the dealer for I'm sure.

    Now the truck gets a crappy 12 mpg highway.

    Any truth to the o2 sensors & antifreeze possible damaging thing? A novice HPTuners owner I would like to ask what, if I can scan and log and tell by the numbers. Would some trims look really off?

    We need help finding the gas guzzling problem.

  2. #2
    Tuning Addict WS6FirebirdTA00's Avatar
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    Log fuel trims and o2 mV and see. I could see it causing issues.
    2000 WS6 M6 (motorless)
    2018 Sierra SLT 5.3L A8 - Airaid intake tube, GM Borla catback

  3. #3
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    Log the o2 sensors as mentioned, but based on the descripitioin they are most likely shot. Also, going through that amount of coolant for that long, you may have to check out the cat's. First confirm primary o2s and change if required. If milage still has not improved, log secondary o2s and install pressure gauge in exhuast in front of cat. If gets this far, post or pm me and I will give you more detailed instructions. You should also inform the shop foreman at the dealership of the problem before the dsm closes your case to avoid another deductable, assuming this was a recent repair. My 2 cents worth.

  4. #4
    Advanced Tuner 2therock's Avatar
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    Quote Originally Posted by mecanicman View Post
    Log the o2 sensors as mentioned, but based on the descripitioin they are most likely shot. Also, going through that amount of coolant for that long, you may have to check out the cat's. First confirm primary o2s and change if required. If milage still has not improved, log secondary o2s and install pressure gauge in exhuast in front of cat. If gets this far, post or pm me and I will give you more detailed instructions. You should also inform the shop foreman at the dealership of the problem before the dsm closes your case to avoid another deductable, assuming this was a recent repair. My 2 cents worth.
    Thank You Both,

    As for the pre cat pressure gauge? What kind of range or reading am I looking for? Cats are factory warranted for a long time I believe. I hope.

    Thanks

  5. #5
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    a spark plug and air fitting can be used to make a pressure bung. I use a vacume gauge that can also read pressure. You should not have any appreciable pressure other then a slight blip when rpms are increased quickly.
    Only worry about this after you have ruled out or replace primary 02 sensors.
    Last edited by mecanicman; 12-11-2009 at 11:45 AM.

  6. #6
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    Quote Originally Posted by 2therock View Post
    I have heard that burning antifreeze will damage o2 sensors.

    Problem = bad gas mpg after heads replaced.

    We have a reg cab 04 Silverado w/5.3 that the water pump went out on, got hot and the heads cracked.

    They were a small enough cracks the antifreeze would consume at a quart a day or so. No smoke but stinky.

    This went on for weeks while while we fought with the extended warranty Co for coverage. Long story but we got them to cover it.

    The o2 sensors were not considered by the dealer for I'm sure.

    Now the truck gets a crappy 12 mpg highway.

    Any truth to the o2 sensors & antifreeze possible damaging thing? A novice HPTuners owner I would like to ask what, if I can scan and log and tell by the numbers. Would some trims look really off?

    We need help finding the gas guzzling problem.

    Moisture kills the heater in the sensor