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Okay so I just pulled the thermostat. I noticed that the oem one is slightly longer than the "oe" replacement 186 one I just bought from summit. Does this matter? Here's a few pics. Original on the left, new on the right.
Also I noticed that there's less resistance on the spring of the old thermostat than the new one. I don't know if that means it's wore out or not but I thought I'd mention it
Last edited by 72Shark_VAL; Aug 5, 2017 at 02:30 PM.
There seems to be something not quite right here. Ok, you put in a new battery and all of a sudden you pegged the temp. You then put the old battery back in and temp was normal. Did you put the new battery back in a second time and verify that it pegged out again? Seems like you're throwing some parts/money at it right now without verifying what the actual issue is.. I'm not trying to be a smartass or hateful. Just want to know that you absolutely verified that putting in the new battery repeats this overheating issue. Very unlikely a battery replacement could cause this but there's been weird stuff happen with C5 electrical systems.
Okay so I just pulled the thermostat. I noticed that the oem one is slightly longer than the "oe" replacement 186 one I just bought from summit. Does this matter?...
Originally Posted by 72Shark_VAL
Also I noticed that there's less resistance on the spring of the old thermostat than the new one. I don't know if that means it's wore out or not but I thought I'd mention it
You can easily test the thermostats. Put them in a pot with water completely covering them. Get a thermometer and make sure it covers the temperature range of the thermostats. Turn on the stove and, checking with the thermometer, make sure they open when the water reaches the right temperature.
There seems to be something not quite right here. Ok, you put in a new battery and all of a sudden you pegged the temp. You then put the old battery back in and temp was normal. Did you put the new battery back in a second time and verify that it pegged out again? Seems like you're throwing some parts/money at it right now without verifying what the actual issue is.. I'm not trying to be a smartass or hateful. Just want to know that you absolutely verified that putting in the new battery repeats this overheating issue. Very unlikely a battery replacement could cause this but there's been weird stuff happen with C5 electrical systems.
Yes I know it is very odd, & no I didn't put the optima back in a second time. I decided to not replace the belts/pulleys or pull the radiator out right now after further looking at it all, but I am going to flush it. They all appear to be in really good shape. I am replacing the thermostat & temp sensor for peace of mind though, cheap parts so I figured wth. I've been wanting to change the manual tranny fluid & rear diff fluid too so this'll be a good time to do that while I have it up on jackstands. Hopefully I won't have anymore overheating/ false reading problems anytime soon.
Last edited by 72Shark_VAL; Aug 6, 2017 at 11:41 AM.
...I am replacing the thermostat & temp sensor for peace of mind though, cheap parts so I figured wth...
Definitely, especially since you already bought a new thermostat and have the old one out, but I'll test it along with the new one before installing the new. It would be good to know if this was the cause of what happened to really have peace of mind.
I know this is an old thread, but my ‘03 Z06 did the same thing today. I went to start it to take it to the shop for some work and it just clicked, even with being connected to a trickle charger. I ended up installing a new battery and when I started it, the engine temp went straight to max. I tried restarting it a couple times on the way to the shop, but it kept doing the same thing. The shop is going check it since they’ll be doing many upgrade on it (ATI balancer, brakes and lines, new tires, etc).
Also I noticed that there's less resistance on the spring of the old thermostat than the new one. I don't know if that means it's wore out or not but I thought I'd mention it
Less spring pressure on a thermostat will usually allow it to open sooner, so I doubt that's your issue.
They found a code for the high coolant temp limit or something along that line. Once reset, the temp gauge went back to reading normal. There was no CEL or any other issues, just the temp gauge maxed out. My guess it was from changing the battery and disconnect and reconnect to DC power.
So if you have the same issue, check the DIC for error codes.
Because you have drained the cooling system, make sure you go through the FSM procedure to remove air from the heads after refilling the system. If you don't do that the engine can suddenly have high temperatures because of not getting the air in the heads out.
