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Old August 12th, 2017, 09:54
Slimer Slimer is offline
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Join Date: Jun 2017
Location: Tempe, AZ
Posts: 91
Re: Temperature jumping from warm to hot and back again

Quote:
Originally Posted by Tim_MN View Post
Steam would indicate a coolant leak ?? Leakage would allow loss of system pressure.

The thermostat and the radiator cap are both routine maintenance items that should replaced every few years, and as a bonus they are inexpensive. Be sure to buy genuine Jeep replacement parts, or the best quality parts the store has. Cheap parts are cheap for a reason. Another thing to look for is leaky frost plugs on the side of the block and the rear of the cylinder head.

The dashboard temperature gauge is not a certified measuring device, it is more correctly described as an indicator. Normal indication is about 210*. If you drive for a whole year and it indicates in the same location every day, everything is normal and OK. If it shows much hotter than normal, you need to pull over until it cools down, and then do some diagnostics. The PCM does buffer temp gauge readings, and temps will vary more and quicker than the gauge indicates. Part of the PCM programming is also to alert to a impending overheat by flinging the needle all the way to the right and lighting the Check Engine Light.

The stock 195* thermostat, unless defective, is already fully open at about 195*.
Maybe, maybe not. In my case, if the thermostat is already fully open how do you explain the engine cooling off so quickly and the guage returning back to the middle? These are confirmed temperature trends using two real-time probes. Anyhow, I am completely befuddled by my overheating . Hoping that the new Hesco Water Pump and Griffon Radiator fix the problem; otherwise I will have to light the thing on fire.
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