Engine ran without coolant

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Asking for a friend :biggrin:

While the owner had the interior torn down he pulled it outside to do a water test trying to fix a leak.  He had forgotten that he had the top radiator hose off as well as the temp sensor sending plug out and the associated heater hose off.  Car sat at idle for about 7 mins before he remembered all of that.  Shutting it off, re attaching all hoses and filling radiator he ran it for a few mins and put it away.   The next day, after completing killing himself, he ran the car at idle for 15 mins.  Nothing seemed out of normal, engine ran fine at idle and reved up to 4k rpm. No leaks, oil looks like it did when changed had a week ago.  Did he dodge a bullet or should he lose sleep?  Anything he should do at this point or just thank a higher being.   Again, asking for a friend  :biggrin:

 
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Have him put some miles on it, close to home. Have the AAA card with him just in case. Based on what you said he is likely OK, but...... Chuck

 
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At least there was plenty fresh oil in it, that's probably what saved the day! And its not like an engine is completely dry inside either.
Just water and no oil would have been another story!
If it runs fine now, I would not really worry too much. Lucky him!

 
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Ask your 'friend' if he heard any gurgling/boiling noises after he shut it off. It's most likely fine. Letting it idle for 7 minutes may not have been long enough for the thermostat to open and pump out much coolant.

I would run it until it's warmed up, with the radiator cap off or loose, and the thermostat has opened up, look for bubbles/froth in the coolant. Install the radiator cap and let it run for a while to build pressure. Check the oil, looking for signs of coolant (milky colored oil). Heads and head gasket would be the first thing that got damaged, high enough to be above the coolant level.

 
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As others have said its probably ok if it wasn't under load.

Water pump seals don't like to run dry though. If there wasn't enough residual coolant in the system I would guess that maybe your friend shortened his WP life by a few miles.

 
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He is probably ok but he should not have put coolant back in until it cooled off. Putting cold coolant into a hot engine can cause the most damage by warping a head.
Be sure he used distilled water also. If not he needs to change and flush with distilled water and 50% antifreeze mixture.
 

 
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