So upon startup today I opened the radiator cap to check for coolant level since I noticed the coolant reservoir is near empty and I have no idea why. When I took the cap off the coolant kind of shot out, I've never had that happen before. Car doesn't run hot nor was the coolant level low but for some reason the reservoir is near empty and the coolant shoot out was odd to me. Any ideas? Car has a brand new(less than 200 miles) radiator in it from mishimoto with their provided rad cap. Thanks

 

Cold engine and pressurized coolant? How is that possible?

 

Coolant shot out when it was hot after driving? You shouldn't be opening it when it's hot, coolant system is under pressure when hot.

If it's bubbling when idling, it could either be air-pockets inside the cooling system or compression is getting in.

If reservoir is near empty and you just recently replaced radiators, check for leaks. Radiator leaks are sometimes hard to catch especially if you're running Water only.

 

Did you crank or run the engine before checking coolant?

 

It shot out because you had started the car and it was warm

 

I would fill the overflow and check it in another couple hundred miles. Could have had an air pocket and sucked from there to keep your radiator full. Unless its low again in a couple hundred miles don't worry about it. As others stated if your are going to take your cap off do it with the engine off and preferably cold. Take the cap off slow and let the pressure release before removing cap completly.

 

The car was only on for 1 minute. Sounds odd to me. Def cold. I will refill reservoir and will keep check on it.

 

Double check that the expansion tank doesn't have anything blocks etc.