Air in rad

[Monk]

Do your find every 9ish months or year , air seems to find way into Anti freeze system

Yesterday I put heater on ,and noticed little (if any heat) and temp seemed to go bit higher,

So I bleed out air on top and bam, heat was out and was running cooler,

What cause air to start ? It's always pressurized in am like always and leak free.

[Roy]

Diesels naturally use antifreeze. Top up the reservoir every 3 months to avoid this issue.
That is until it becomes a more prominent leak.

[whitehumh2]

You need to change your coolant to a Heavy Duty Diesel Specific Coolant.
 
The reason that there is coolant loss is due to evaporation caused by the shockwave in the cooling system when the power stroke occurs. There is a brief time where the coolant is actually pushed away from the cylinder wall and then when the coolant rushes back some of it goes to vapor.
 
You need either a CAT or Cummins Diesel Specific Coolant, they both have additives to greatly reduce this, GM Dexcool does not! Note, the water is the issue and what is evaporating!
 
I would highly suggest the Evans Waterless Coolant since this will completely eliminate this issue and every other H1 cooling system problem like overheating!!!
 
http://evanscooling.ca/heavy-duty-diesel/5-evans-hdc-bottle-heavy-duty-diesel.html