I hate to say it but it could very well be a headgasket. Mine did the same thing and since your radiator just went out. That could be the sign that it is building too much pressure. I am sure i may get a few nay sayers but from a guy that has litterally replaced dam$ near everything under the hood and spent easy $15k doing so, i know the $hit that breaks. I have an 08 job 1 and have had bad injectors, cracked heads, and blown head gaskets. I discovered the coolant blowing out around 40k miles and me being new to the diesel world found out the hard way that means blown head gaskets possibly. I thought the quick fix would be to lower the coolant in the degas bottle and let er ride. I drove it for another 40 k miles before i had someone look at it. The coolant puking became more frequent and would only do it under high hp settings and at high speeds. ie racing a tuner car
. When i had the tech check for blown hgs he verified by testing the coolant for exhaust gasses. This is my first suggestion for you. Go get your coolant checked for exhaust gasses. It is a quick and easy check. If it doesn't show signs of exhaust gasses your not out of the woods yet. I had my headgaskets replaced only to find out that the heads were cracked and boost was causing my coolant over preasurization. I then had to take the thing completely apart and replace the heads. Lukily the shop warrantied their work and it only cost me the price of the heads. While the truck was apart the first time i had the injectors tested and 6 out of the 8 were low flow. So i replaced all 8. I had the new ones checked again when the cab was off to replace the cracked heads and they tested good. Proved to me that the shop could tell the difference between good injectors and bad ones. I also replaced the degas bottle with the updated version on the i think 09s and definitely the 10s. Did a full EGR delete as well as replaced the glow plugs, water pump, wiring on the HPFP "(Issues with it rubbing causing truck not to start"), both radiator hoses for the new 2 o-ring version, thermostats, and intercooler boots while it was apart. I realize i may have changed a few more things than most but i didn't want to have to take the thing apart because i didn't replace something that was easy to get to while the cab was off.
Also put on
head studs - goes without saying
MBRP intercooler pipe
Diamond EYE downpipe
new serpentine belts
flushed the powersteering fluid
flushed the trans fluid
added a easily replaceable external trans filter. (Allison spin on type)
I don't mean to be a downer but you shouldn't write it off as a over full degas bottle. That is just a bad idea. Get her tested and find out for yourself what the issues are. The 08s are $hit IMO. They have the most issues because of being a new model year and we both have Job1s. Which are the worst of the worst.
Let us know what happens bud,
08 JOB 1 F-250 Lariat Crew Cab, S&B INTAKE, H&S Blk MAXX, 5" Flo PRO, EGR Delete, Air Dog 165, Upgraded Bellows, MBRP Intercooler pipe, 4" Down pipe, Tial Wastegate, OUO T bars, ARP studs, Bestop pwrbrds
***Legal Disclaimer: Anything I say about my vehicle on this website(Powerstroke.org), pertaining to modifications, is only to gain acceptance from my peers, and does not actually represent anything actually existing on my truck, and thus, cannot be held against me in any issues.