Coolant System Issue

[stephenricci]

I apologize if this subject has been covered elsewhere but I could not find anything directly related in my search on the subject. My issue began after I got home from my 17 mile ride home from work. After I parked the bike, I could hear a gurgling sound coming from radiator overflow tank. I checked the tank, and sure enough it was bubbling. I let the bike sit for a few hours then checked the tank. The level of fluid was at the Low mark so I filled it to the High mark and fired her up. I let her run and when the temp starting reading about 1/2 between the red and operating temp, the fluid level began to rise. At about 3/4, the fluid overflowed through the overfill tube and onto the floor and the fan never came on. I assumed that it was a stuck thermostat. So, since I am a "while I'm in there" kind of guy, and since I had the parts on hand, I decided to change the thermostat, water pump and hoses (OEM thermostat and pump). Thanks WingAdmin for the outstanding step by step on that. I got everything put back together without any issue. I also checked the radiator fan by directly applying power and the motor turned on as it should. I fired up the bike after flushing with distilled water and filling with antifreeze but only to the Low level line in the overflow tank. Well, same thing happened. The fluid started rising when the temp gauge reached 1/2 and at 3/4 it was at the full line and the fan motor never came on. Could this be a bad thermostat switch? I would really appreciate any advise on what to check next. Thanks in advance!

[DenverWinger]

I think it's even simpler than that, I bet you have a defective radiator cap that's not holding pressure. There should be no bubbling until the temp gauge is clear over to the red.

Any ol' standard 13-15 psi automotive radiator cap of same size will work fine as long as it is the coolant recovery type.

[stephenricci]

Thanks, I think that I may have a Stant cap somewhere. I'll give it a try. If not, I'll take the cap off my Naked and try it out. I'll let you know how I make out.

[DenverWinger]

And the fan should be running if temp gauge is at 3/4 scale...

Fan failing to kick on is usually just corrosion on the connector pins at the switch. Fan switch rarely fails. Fan switch is the one by the thermostat with the big rubber cap and two wires. The other one is the sender for the gauge. If you jumper the two connections inside the switch cap and the fan runs that confirms all other associated circuitry for the fan is good.

[stephenricci]

Sir Denver, thanks so much for the help. I put a Stant 13 lb. cap on and ran it with the coolant level at the low level. The level rose a little after getting to about 3/4 level. I shut it down and let it settle for a while then topped off the level to full. I ran it again almost to the red and the level remained almost constant. The fan never kicked on so I will double check my connections and try the jumper trick. I did disconnect that switch when I changed the thermostat and cleaned the male parts of the switch but I did not touch the harness side. Does it matter which way the switch connector is plugged back in? Thanks again for the help.

[DenverWinger]

Electrically it doesn't matter which way the connector goes on the switch, it's just a switch. But it might only "physically" fit on the switch one way... you should be able to see that just by looking at the switch and connector. Been a long while since I've had mine disconnected, so don't remember...

Sounds like the new radiator cap did the trick.... So many times I've seen people throw money and parts at a cooling problem, completely overlooking the lowly cap...

[stephenricci]

Thanks again for the info. It might not be until next weekend before I troubleshoot the fan but I will check as you recommend and let you know how things work out.

[stephenricci]

OK, I jumped the switch plug and the fan comes on as soon as I turn the key on. Is the switch the only thing that could be causing the fan to not come on during operation? I have a new switch coming tomorrow but is there is anything else that I should check? Thanks.

[DenverWinger]

Has to be the switch then. Are you sure you actually got the engine warm enough that the fan should have turned on?

[stephenricci]

Yeah, after I got the cap issue solved, I let it run until it was almost to the red and still no fan. I got the new switch in the mail this afternoon so I will be putting it in tomorrow. I'll let you know how I make out. Thanks!

[stephenricci]

Well it turned out to be the switch. I installed the new switch this morning and all is good. Thanks for all the help!