So I replaced my DCCV a couple months ago and when I did, I must not have put the hose that goes to the thermostat housing from the aux coolant pump (I think that's what it is anyway) back in the right spot because the supercharger belt ate a hole through it. Ordered the new hose, and got it installed. Started finding small puddles of coolant. I looked and looked, and I couldn't find the source. Thought maybe I missed a hose clamp or something. So I have a new reservoir on order because they're prone to leaking, and I've been driving it and keeping an eye on the coolant level since it's my only vehicle.

Tonight on my way home I noticed the temp gauge didn't move like at all for awhile on my short trip home, which was weird. I have one of those bluetooth OBDII adaptors and the Torque app on my phone. Pulled it up and it said my coolant temp after 5 minutes of driving was only like 95*. Very weird. I was almost home, so I continued, then the temp went from 95-115-145-180-190-225-almost 240 before I pulled into a parking lot and shut it down. That OBDII adaptor really saved my behind because the dashboard dummy gauge was just coming off the normal by the time I turned it off. Fan kept running after I shut if off and it was back down to 200 in literally like 1-2 minutes. Restarted it to drive the remaining half mile home and by the time I was home it was back over 220. What would cause this to overheat so quickly and cool off so quickly? Air in the system? Water pump? Thermostat? I'm beyond frustrated and hoping nothing got hurt when it got hot. Ideas or solutions?

 

My first guess is a thermostat sticking then operating. Hopefully one of the cheaper fixes.

 

I'm thinking an air bubble. Pain to get out but if you have a hill you can use or jack up the front of your car

 

I'll try the burping and see if that fixes it. After that I guess it's thermostat time, lol. This thing is going to nickel and dime me to death! Makes me miss the cheap parts for the Envoy I had!

 

Update! Got what I thought to be all the air out of the system. Never noticed another problem. Got home after a bit of a spirited drive and popped the hood to check everything over. Noticed an antifreeze kind of smell. Went to open the expansion tank for the antifreeze and was met with lots of hissing from air escaping, then antifreeze bubbling over and out onto the ground. After it finished its fit, the level dropped quickly to below the add mark (unsurprisingly) and I worried about a head gasket leak. Got a test kit and the antifreeze doesn't test positive for combustion gasses, soooooo what else could it be? Air still trapped somewhere? Thermostat? So frustrating!

 

The thermostat is cheap, and they often fail by intermittently sticking. Just change it before your engine decides it has been stressed enough.

 

Ya when I replaced my thermostat, I checked it (original one). It was slow to open, and wouldn't open fully.