Radiator caps

[triton28]

I have seen 2 different Bar ratings on Voyager XII radiator pressure caps in use. One is 0.9 and the other is 1.1 Bar.
The 0.9 Bar radiator cap would open at 13.05342 lbs. and the other cap would open at 15.45918 lbs. pressure.
Apart from the obvious differences in opening pressures and the slightly higher boiling temperature due to increased pressure, does anyone know which is the correct pressure cap rating?
Was one rating introduced after a certain model year and both are correct depending on the model year, or was there a run on alternate, aftermarket and not from Kawasaki Motors, supplied caps with the different rating.
I'm also wondering if the 1.1 Bar, being 2.4 lbs greater in pressure before opening, would contribute to premature wearing out of hoses/seals/gaskets since it is 18.38% higher opening pressure than the 0.9 Bar pressure caps.
Not a major issue, just something I have been meaning to ask for awhile.
Dave

[Lumpy Rider]

Pages 54 and 55 of the service manual states that the maximum pressure for which the cooling system was designed for is 15 psi, and the parts fische shows that only one pressure relief cap (#11012-1084) was used for all model year Voyagers as well as for hundreds of other Kawasaki power sport applications dating back to the 1970s. The manual also states that the range of the pressure relief cap is between 11 and 15 psi and if the cap is not testing in this range it should be replaced. I could find nothing on the 15+psi cap you mention. Not sure about extra wear and tear from using this cap except that it could promote leaks in the system due to the extra pressure.

[triton28]

I guess I will stick with the 0.9 pressure caps since they are lower pressure.
Thanks,
Dave

[Lumpy Rider]

Hi Dave...another factor is altitude. The boiling point of coolant decreases as altitude increases. In as much, a 1 bar is only 1 bar at sea level. The 1.1 bar cap may be for a high altitude applications and may actually have come from a Toyota. I have heard of the Toyota rock crawler guys here in Colorado using them. All very interesting. For the Voyager I think a concern is blowing out o-rings in the cooling system or even seams in the radiator if you are at or near sea level.
-Duane