have you ever changed the antifreeze in the sled? you should as it breaks down over time and doesnt help protect against corrosion as well, and it gives you a reason to inspect a couple of componets,like the thermostat. Drain the coollant via the lower radiator hose on engine will get the most out of it, you can then tip the rear of sled up and empty alot of the coolers out or remove the rear cooler line and drain.(yes, its messy)
After you check your thermostat(its in its aluminum housing there below the front fill bottle) what I do is elevate the front( place a 4x4 block of wood under each ski and leave the track on the ground) then all the air from the system will go up front and its easier to run the sled and let the air escape thru the fill bottle. What you want to do is run the sled at idle and it will push the air from the system, check and make sure you have heat in both of the running board coolers and the rear exchanger. Youll find this works much better then the rear bleed hole method and it burps the system better. The viper has a little bit differnt set up then a srx as it has a bypass on the front cooler. I do it this way for both and have never had an issue.
