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Discussion in 'Technical and Troubleshooting Torque' started by jack_1313, Apr 16, 2015.

  1. #1 jack_1313, Apr 16, 2015
    Last edited: Apr 16, 2015
    If a thermostat were stuck closed, would the radiator heat up at all? That is to say, does the thermostat stop the flow entirely or just restrict it? Cheers

  2. Yes it would heat up.
    You still have an engine generating massive amounts if heat, but if you're riding at a decent speed, it will probably run cooler then the designers intended, which is not a good thing.
  3. Whoops, I am idiot. Meant to write stuck closed, not open
  4. Stuck closed will cause it to over heat.
  5. Stuck open will cause overheating. You can test this by letting the bike run at idle and see how quickly the thermo fan kicks in, if it happens quickly, then you are probably looking at a stuck thermostat.
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  6. Bike is running way too hot according to gauge, but the radiator is hot. Assuming there is no flow through the radiator at all when the stat is closed, then the problem cannot be stuck stat, as the radiator would remain cold. Will test anyway when I get a chance.
  7. thermostats usually have a small hole to let a little water through, so radiator may still get hot even if stat is not opening, just the water in engine may be even higher temp
  8. The radiator will get hot even with a stuck thermostat because there's no water flowing thru the engine and the water is heating up and boiling etc.

    Have you taken out the thermostat and placed in a pot of boiling hot water to see if it opens up or not?
  9. Are you Having to top up the water all the time?
    Is your cooling system pressurising and the hoses going hard to squeeze ?
  10. A thermostat should keep the water flow closed until the engine warms to operating temp. then it opens allowing flow. while you would get some radiating heat from behind the thermostat and the engine itself, but I don't think it would make your radiator Hot very quickly if the thermostat was staying closed.

    what colour is your coolant? do you use water? is there any oil in the water?
  11. Only symptom at the moment is the bike running far to hot for weather conditions. Fan working, but bike borderline overhearing in traffic, at least according to gauge. Not loosing coolant. Problem only started today, so I haven't had a chance to investigate yet.

    I suspect a stuck stat or faulty temp sensor. Will investigate asap. Sorry bout blunt writing. Using phone from work.
  12. does the bike Feel hotter than normal?
  13. Temperature guages can be notoriously inaccurate.

    Coolant loss is the most reliable sign of engine overheating.
  14. This makes no sense to me
  15. I think hornet meant stuck closed. Made same mistake I did :)