So I have an 03 with about 45k miles. I have changed out all hoses And did a radiator flush per service manual. I also replaced the cap and both fans which had gone bad. I notice small droplets of fluid coming from under the radiator cap after riding just about 3 miles to my favorite little hang out. Overflow bottle is new style and no issues. Could it be that original thermostat is going bad and building up to much pressure? Any other thoughts? Appreciate input.
Does a thermostat that might be going bad be responsible for higher pressure in the system? Can it be the cause of overheating when in long bumber to bumper type situations?
T stat only controls minimum temp of 178 ish. It's fully open at about 212 so beyond that temp, cooling is from either moving down the road or fans kicking in. In traffic they will cycle on and off between 217-208f. In the cooling system being completely full expansion from heat will reach the approx rating of the rad cap and any extra will bleed off into the overflow bottle. On cool down the system will enter a vacuum state and suck fluid from the bottle back into the rad. Two sealing systems in the rad cap. On for pressure and vacuum control and the cap perimeter. Leaking at the perimeter could be from a poor sealing surface on the metal tube itself. It should not leak, ever. Look over the sealing surface and the tabs to see if the cap sits square to the pipe. Slight tab bending on the cap or the tube flange itself might true it up but it will have sight influence of the caps pop off pressure . Testing the cap itself means little and actual 1.1 bar needs to be tested on a actual install of bike. Just so happens I made a tool just for that, used with a Stant pressure tester.
I had the same problem a few years ago. It ended up being a bad seal on the metal tube, from the surface not being clean from factory paint overspray pitting. I ended up using a ball end wire brush that fit the inside of the neck in a drill to clean all the surface. I also replaced the cap with a Moose Racing 1.1 BAR Radiator Cap. It uses silicone seals instead of rubber, that IMHO contours and seals better. I haven't had a problem since, and that's been about 3 years ago.
The rad cap on my 2007 is real hard to secure. For some reason it appears to seal but if I force it with the palm of my hand pushing down it will turn another 1/16th turn or so.
This solved my issue of leaking cap.
Everything is JMHO. Accuracy is not assured.
Originally Posted by Mark Twain
The more I know about people the better I like my dog. -
2007 VRSCX 0461 / 1400
2003 VRSCA – Gone but not forgotten.
2002 Road King Classic