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  1. #1
    Member URLUZN's Avatar
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    Default C6 ZO6 Overheating

    My 08 zo6 at @ 20k miles had its first overheating issue which was the results of a burned plug where the wiring harness and the harness to the electric fan connect. I was informed of this issue from reading a post on this forum. Dealership corrected. Now @ 27k miles the overheating has returned. It appears the electric fan is not coming on again. I checked the plug and all is good. What temperature should the fan come on? I thought it was around 210. I don't want this engine to experience again the temperatures it was exposed to from the first failure. The oil pressure would get to 20 psi at @ 200 deg which I have never seen this low before. Now folks, this was a very cool nite, AC off and driving very easy. The coolant would get to 218 while stopped at traffic lights. Once you get rolling again the coolant temp would go back to 199 or so and the oil temp back to @176. Your help and information would be appreciated.

  2. #2
    Technical Writer for Internet & Print Media
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    If you are seeing 218°F coolant temp, 200°F oil temp and 20 psi oil pressure at idle in traffic, your engine is not overheating.

    You can change the fan-on strategy but you need a custom tuner who knows how to do that.

  3. #3
    Member URLUZN's Avatar
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    What are the safe operating parameters for the LS7? Oil pressure & temp, and coolant temps before there is a concern for engine damage? I'm curious to how low of oil pressure you and other owners are seeing. What were the temperatures both coolant and oil at the low oil pressure reading?

  4. #4
    Technical Advisor c4c5specialist's Avatar
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    HI there,

    Coolant, as high as 235 without issue.

    Oil temperature, as high as 275 without issue.

    Oil pressure, as high as 90 psi at higher rpms. Remember, due to the dry sump system, oil pressures are HIGHER than those without dry sump.

    However, your fan should be on in some capacity around 210, at a lower speed. Remember that these fans are NOT on/off type fans. They are duty cycle controlled by the fan control module, meaning that they are on by percentage of using electricity. This value is between 10-90%. This module takes inputs from the ECM as far as AC pressures and also coolant temperature to determine effective percentage.

    Somethings up if they are not on in some capacity at 210.

    Allthebest, Paul
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    I looked at the cooing fan vs. ECT tables in the cal for my '12. At 210°F the fan "percentage" is 39. The cooling controller really doesn't ask for a lot of fan until the ECT bets to 225°F. While it's possible the fan calibration for an '08 might be different, I can't imagine it being greatly different.

    As, Paul, references above, fan strategy is also tied to hvac pressure.

  6. #6
    Member URLUZN's Avatar
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    Thanks guys for your help. The dealership tech told me that the fan should come on around 225 deg. This just didn't sound right to me. I could of sworn I have heard the fan running at 210 before and speeds up to try to maintain there about. So, I am going to test again and see if the fan is running at all. Let you know what I find out. Guys like you on this forum seem to know more about these cars than techs at the dealerships.

  7. #7
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    We'll guys the fan is running at a low percentage rate at 214 deg. I feel better now knowing it's running at some capacity. But the low oil pressure is a little troubling though. I've had the oil temp hotter than 200 deg before but never seen the oil pressure below 26 psig. The 20 psig at 200 deg makes me little nervous. Your thoughts and comparisons are welcome.

  8. #8
    C6 ZO6 Overheating Tuna's Avatar
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    20 psi at idle is no concern to me - so long as it goes up with RPM
    Tuna
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