The thermostat does NOT activate the fan. The fan is activated by a thermosensor. The thermostat only regulates coolant flow in the system to maintain the proper temperature. It is NORMAL for a coolant to overflow from an open radiator when the engine warm up (the coolant expands when heated). The manual radiator fan switch was really stupid. It's a GOOD THING you got rid of it! There is no need to modify or change the design of the machine in any way. There is also (normally) no need to "flush" a cooling system. If you want the bike to run right you just need to restore it to the original condition. By and use a factory manual, learn the basics of liquid cooling systems.
On Sunday, March 23, 2014 9:32:47 AM UTC-7, EGrider wrote: > > Javier, I didn't know that the thermostat activated the fan. I wonder how > it does that? I had guessed that the temperature gauge on the thermostat > bowl did that, but that may just be for the meter. I originally wrote, then > deleted, that a previous owner had installed a manual fan switch before I > bought the bike. That was lost when I changed the wiring harness. The fan > did not come on. Good point there. I'll check it manually and confirm that > it does run. The bike does have a working temperature gauge, as I saw it go > up, but I forgot to look at what it was reading when I shut off the bike in > a panic. I'll keep an eye on it next time. > > I'm not sure of the sequence of events as engine temperature goes up. Does > the water pump circulate water all the time? If so, how does that happen > when the thermostat is still closed? Trying to get a basic understanding of > this. Never had to think about it with CBs and Nighthawks, etc. > > On Sunday, March 23, 2014 11:31:46 AM UTC-4, EGrider wrote: >> >> My Nighthawk is the least problematic of all my bikes. May I ask a >> non-Nighthawk question? I'll write this as a numbered list to keep it short >> and to the point. >> >> I've written before that I like V30 Magnas. I've been working on a $200 >> wonder from craigslist on and off for the last 18 months to educate myself >> and to have a running backup to "old faithful." >> >> 1. When I started the bike up periodically during the winter, I noticed >> that it started to smoke off the engine after it got up to temperature. I >> couldn't tell where it was coming from exactly, but it was off the back >> cylinders under the battery, coolant tank, and second fuel tank. >> 2. Now that the weather is nicer, I decided to get the thing on the road. >> I noticed that the coolant reservoir was low, so I put in some antifreeze. >> It dumped all over my garage floor. Apparently the smoke was from coolant >> dripping onto my rear exhaust pipes from a leak in the tube. >> 3. I ripped bike apart and changed the line from the radiator by the cap >> to the bottom of the overflow tank. I took it off a third parts bike. >> 4. As it was really hard to see where the level was on the overflow tank, >> I ended up filling it past the top mark. >> 5. I started it up. Since it no longer dripped coolant on the exhaust >> pipes, it no longer smoked. That's good. >> 6. When it got up to temperature, coolant gushed out the radiator cap, >> and I shut the bike off. That's bad. >> >> Where do I go from here? I'm thinking I should troubleshoot in this order: >> 1. Drain the coolant down to the correct level and restart bike >> 2. Change the radiator cap for one that I know can take the pressure and >> restart bike >> 3. Put the thermostat in hot water and confirm that it opens. Replace if >> it doesn't. >> 4. Swap out the water pump with one from another parts bike I bought >> >> One thing that's missing from the above is "flush the cooling system," >> because I'm not sure how to go about that. I do have the Clymer manual, and >> it talks about pressure testing the cap and cooling system but not about >> flushing it per se. I could drain the system and refill it, probably should >> anyway with an old bike, but does that guarantee that the coolant >> circulates when the bike gets hot? >> >> If you have been down this road with old bikes that you've resurrected >> and have a minute, I'd appreciate any advice. >> > -- You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/nighthawk_lovers. For more options, visit https://groups.google.com/d/optout.
