I’ve attached a video; this was taken after driving for about ~30 minutes.

Could this be a small leak in the head gasket? It definitely doesn’t seem like a full blown failure, however it seems like this could be a start to a much bigger problem.

I had to top off my radiator about 10 Oz today to get it completely full (reservoir tank level was otherwise full), however I did just change the radiator about 250 miles ago. I figured after 250 miles it would have purged all the air out by now, as I have driven it at least 5-6 warm up/cool down cycles.

Coolant temperature is usually right around, to ever so slightly above the 1/2 mark when driving.

Im going to get a combustible gas tester and fluid tomorrow, however wasn’t sure if anybody had ever seen this before.

Thanks all.

 

1-Check your new radiator really good, my new radiator had a tiny pin hole, I had to return it.
2-Replace your radiator cap.
3-After installing the new radiator- squeeze the driver's side radiator hose a few times.

 

 

Well I tried burping the system and the bubbles still exist. Everything else seems completely normal; coolant temperature is generally around 205-212F (195F thermostat) around 65-70mph on the interstate, and creeps up to 215F at idle after sitting for a couple minutes. This is in 80-90F weather, and verified with a scan tool. For a 400 mile journey, the max temperature was about 220F going up a small incline, but it came back down almost immediately once I leveled out.

The hoses pressurize and don’t feel overly hard either. I don’t smell coolant ever and the coolant level has not dropped.

I ran a combustible gas leak test multiple times, and every time it passed (blue fluid didn’t change color). There was one instance the fluid color changed to an ever so slight shade of dark green, but after follow on pumps, it changed back to the original blue color afterwards. I’m thinking this was a fluke because after 5x follow on tests, it passed every one.

Oil condition is normal as well, and isn’t milky.

Zero misfire codes or anything CEL.

I’ve noticed on cold start up, the bubbles don’t start until the engine is up to temperature (possibly when the thermostat opens). I’ll drive the vehicle around for 20-30 minutes, then pop the hood and that’s where I notice the bubbles. However, once I park the vehicle and let it idle for a couple of minutes, or drive under a very light load, the bubbles will eventually stop.

I’m going to do a leak down test eventually to see if that uncovers anything, and then eventually send in an oil sample to see if it comes back with coolant/water, but for the time being everything seems relatively normal.

 

Did you check/replace the radiator cap?

 

I replaced it about 8k miles ago when I did my engine rebuild, however apparently it was either a bad one and I didn’t notice until now or it just went bad recently, but either way I put a new one on and all the bubbling has stopped as of now.

The temperature gauge is also much more steady now and doesn’t fluctuate quite as much as before.

Thanks hummerz and ski.dive for the replies!