Join Date: Nov 2009
Location: Lander, Wyoming
I wonder what others may think on this topic. It seems to me that a hypothetical air bubble would flow through the system to the radiator (high point) the same with 0, 5, 10, 15......... pounds of pressure on both sides of it. With the cap on or off.
On a KLR it normally would, IME.
Some cooling systems on other models and other brands and automobiles have air bleed screws at air trap points in their systems. Sometimes right on top of the thermostat housing. I've even seen air bleeders clear down low, on top of coolant pump housings.
My KX500 has an air bleed at the rear of the cylinder head, because the hose comes off the front of the head & the engine sits at about a 15 degree incline.
The side mounted thermostat on the KLRs and using center stands vs side stands during cooling system re-filling might affect the volume of air that needs to be 'burped'. Improperly locating the air vent hole of thermostat may affect purging of air in the system.
The initial start-up after cooling system re-filling is usually suggested to be performed with the radiator cap still Un-Installed.
Modify at "YOUR OWN RISK"!
Still riding my 1987 KL650-A1. 85,000+ miles & counting