First time posting, long time viewer of the forums

Driving for a short trip to the gas station tonight, and on the way back (roughly 5 minute drive) I noticed a fairly loud bubbling sound, drawing my attention to the instrument cluster, where I immediately noticed an oil temp warning light, and the temp gauge pegged. I immediately pulled over and killed the engine. I waited for the temp to return to lower-than-normal, and the bubbling from the coolant overflow stopped. No noticeable fluid leaks, and oil level was normal, I have not checked the coolant level yet, as it is still hot as I am posting. I started it up, and drove it the remaining ~2 min drive home, and the temp did rise, but no bubbling, and the gauge was not pegged as it was before

I have read a lot of threads about coolant bubbling, and about engines overheating, but none regarding anything such as my case. I have read a lot that this is a telltale sign of a blown head gasket (I’m praying that’s not the case) but from what I read, that would cause constant bubbling in the coolant. Other suggestions were new rad cap (mine has not been replaced since I’ve owned the truck) and possibly thermostat or water pump.

Any suggestions or ideas on what this might be? I appreciate any help.

(3.0 2007 Ranger, ~215k miles on original motor)
*EDIT* I popped the rad cap off first thing this morning, first thing was very obvious, I’ve got chocolate milk instead of coolant in the radiator. Second thing, the radiator is only 3/4 full. I think this gives me the answer I need (but not necessarily the one I was hoping for)

 

Update for those who anyone who might have this issue in the future:

It ended up being a ruptured transmission cooler (internal to the radiator) which allowed a colossal amount of transmission oil leaking into the radiator, causing a pink-tinted sludge, which was nearly impossible to remove. I wound up installing an auxiliary transmission cooler to the lower frame just in front of the AC condenser, and connected it in series to the pre-existing transmission oil cooler. At the end of the day, due to the sheer amount of oil in the radiator, I ended up biting the bullet and replacing the entire radiator as well (after about 6 flushes of Blue Devil Radiator Degreaser and about 5 days of work). I suspect that a bad thermostat was the cause of this ordeal, causing it to overheat over the course of a 5 minute drive, so that, and the radiator cap got replaced. Even though I replaced the radiator, I just capped the internal transmission cooler to reduce the number of points of failure in the future, since this is the second radiator I've installed in the truck in the past 2 years. The entire process involved cutting the steel transmission lines which ran to the radiator, and connecting 3/8" transmission tubing to them to route the lines to the new cooler. After topping off the transmission fluid (which shockingly didn't have a drop of coolant in it, motor oil neither) and a week of work, she was back on the road. 300 miles (200 of which were a single non-stop trip) and she is running just fine with no (new) leaks.