Radiator Cap (on the fill tank, not actually the rad)

[Nachtwulf]

Hi Smitty,
It is always the small stuff that starts to get your attention when you really get "into" a vehicle. Well, you are in luck. Radiator caps are pretty much standard throughout the vehicle spectrum with a few oddballs here and there. NAPA or any other decent parts store should have a suitable replacement once you tell them what engine you have. Keep in mind that diesels do indeed like to run at higher temps than gassers, and that means a higher psi rating (at least 15) on the cap itself. Even my little five cylinder Mercedes runs 15 psi and about 180 deg F, but that means the thermal values also contribute to a clean burn and better mileage (even on WVO).
Hope this helps, and I wish you the best with your new bus!
Lee

[the_experience03]

I bet Dorman will have a suitable cap. Look in the Help! section at the parts store. Ignore the application listing because you aren't going to find your bus listed. Just find one that fits.

[Nachtwulf]

For every pound of pressure exerted on the coolant in the system, the static boiling point of the coolant is raised by approximately 3° F.
Most liquids have a specific "boiling point", which is the temperature at which the liquid begins to change to a gas. If pressure is applied to the liquid, it must become hotter before it can boil. Pure water in a cooling system will boil (at sea level) at 212° F. At higher altitudes, atmospheric pressure is less than at sea level. Example: Water at 5,280 feet will boil at a mere 203° F. A cooling system that is under 15 pounds of pressure however, will now allow the water to reach nearly 250° F before it can boil. Even at this temperature the water is able to circulate through the engine, cooling parts that are at a much higher temperature without the water boiling. As long as the coolant remains in liquid form it can do it's job and transfer heat to the radiator so it can be dissipated. Coolant that is boiling cannot transfer as much heat and engine overheating is likely to occur if the coolant turns to a gaseous state. Steam adjacent to a hot surface, such as a combustion wall, can actually act as an insulator - thus preventing any heat transfer to the coolant.
Plus, modern antifreeze/coolants are designed to keep the boiling point of the radiator fluid mix at least to 250 deg. F. This is without any pressurization at all, so remember to keep your radiator mix at 50/50 even during the Summer.
This also helps with the lubricants, anti-rust, and anti-corrosion components of the antifreeze/coolant, it helps keep your vehicle HAPPY.