TY395e combustion in coolant?

Are you seeing bubbles in the radiator or did you have a coolant analysis done to determine that there are combustion gases in the coolant?

If you have confirmation of the gasses in the coolant, and not knowing the history of the engine, my first move would be to check the head bolt torque. If you get any movement of the bolts while re-torquing then that might be all it needs.

If that doesn’t solve the problem, then you are going to have to pull the head to see what is going on. With luck it is just a bad head gasket and you will get a chance to clean and inspect things once it is opened up. I would probably also take the head to a machine shop to have it checked for flatness and magna-fluxed if possible.

If everything else looks good, put it back together with a new head gasket and fresh coolant. Run it and test again.

At this point it is still a detective game.

How many hours on the engine?

Where has it been? Any possibility it was frozen and has a cracked block or other damage?

I agree, if you have access to a diesel engine compression tester and or a leak down tester to test the cylinders that should give you a idea of the cylinders involved. If you are not aware these engines require a second head torquing after 10 or so hrs of running time. and to have a machine shop look at the head for flatness is a good idea. If that is not possible a machinist grade straight edge can give you a idea if you are ok.

I have seen 3 different references to head torque specs for the ty395e engine 67-81 ft(to me to low) lbs and 89-100 ft lbs(seems reasonable) and 110-125 ft lbs(to high) so I suggest to call a parts dealer here in the states and ask what they use, and use your best judgement.