I think i know the answer; hope I'm wrong.

2004 Freightliner M2-106 with replaced short block engine.
I have fuel coming out my radiator bottle overflow.
Did I blow the head gasket?
Didn't do this until I recently got it hot.

 

Sorry; 3126 Cat.
Had a recent upper radiator hose failure, probably related to the fuel in coolant. Since replaced
with a new hose.
Cut the end off old hose and re- attached it and poured the contents of an indian tank in, about 4 gallons,
but was hot till I limped it home, about 10 miles.
Just don't know where the fuel is coming from?

 

By the way, that is one chillin' puppy!
My Malamute, Champ, is 14 yrs old, and rear legs are failing fast. Won't be with us much longer; it breaks my heart.

I think you nailed it.
Several you tube video searches of "fuel in 3126 Cat radiator reservoir" found the same thing.
seems I now need some more specialty tools that I probably will only use once.

6 each 3126 injector cup - sleeve
Cat sleeve - #227-2911
Cat remover - #151-4832
Cat installer - #221-9777

So looks like the head doesn't have to come off after all.
(Phew! I was sweating that one.)
Still looks like a lot of work, and several days of downtime.
Glad there are several step by step tutorial type videos uploaded.

 

Thanks for the input, but, no cooler on the little kitty Cat 3126.

I have this thing maxed out on HP in the computer;
that, plus the heat - did the sleeve O rings in.
The injectors are in the combustion chamber, so very hot,
and the sleeve separates the coolant
running around it from the fuel. Lots going on in there,
and since fuel is higher pressure,
it overwhelms the overheated O rings,
and goes into the 5-20 lb. pressure coolant.

 

Thanks; saw that - just mine is for the 3126 Cat.

Cat dealer tool expands three raised sections into recess on inside of sleeve.
Reminds me of the design of a exhaust tubing expander, where the screw turns the sections on internal tapers.
There are several manufacturers or jobbers that use a tap on the bottom, to tap into the inside,
and pull sleeve from these cut threads they just made. (Not too keen on chips from tapping going in head.)
Same result - just different approaches to the same problem.
I also noticed the different jobbers had all black O rings; OEM has a green and a black.

I ordered all from Cat Dealer, to be in for Tuesday or Wednesday.
Tearing the injectors out to prep it tomorrow.
Good luck to me.