iThinkergoiMac Posted July 14, 2016 Share Posted July 14, 2016 So I'm a bit stumped on this one. When I bought the bike, the previous owner hadn't taken the best care of it. One thing I found pretty quickly was that the coolant was very low. I flushed the system and put in new coolant, but I still had issues with the bike overheating, so I replaced the fan switch and installed a VTR1000 fan so that it blows out instead of pulling in. This helps, but the other day I got stuck in traffic in 80F weather and the bike kept warming up. I finally decided to lane split when the bike got to 245F and that kept the temperatures manageable until we got past the traffic. I was riding with my dad and he noticed a fair amount of coolant coming from the overflow tube. This happened before, but it was right after I had topped off the coolant and so I figured it was purging extra coolant at the time, but that was several weeks ago. Once I got up to speed, the bike quickly dropped to normal operating temperature (175F, give or take a few degrees). I'm not sure what's going on here, nor have my searches yielded much in the way of results. The bike cools just fine while moving, but any coolant I put in the reservoir just gets dumped and it slowly overheats if I stay still for too long. I've considered adding a manual fan switch, but that's only really sidestepping the issue. There isn't a leak, as the bike shows absolutely no signs of leakage when it's just sitting. It's definitely coming out of the overflow tube attached to the reservoir. Link to comment Share on other sites More sharing options...
Member Contributer V-FORE Posted July 14, 2016 Member Contributer Share Posted July 14, 2016 I just got through replacing the thermostat on mine, it was stuck wide open, I also replaced the fan thermo switch & hoses. I read through all the post about people switching fans and manual switches, then I realized that Honda has more research on all these issues and kept it stock and no issues now. Maybe try changing out the rad cap? since that is what controls the overflow bottle that is the limit of my knowledge.. Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted July 14, 2016 Share Posted July 14, 2016 I am not a fan of the VTR fan blades, they work great while moving at 15mph+, but they are awful while stuck in traffic, because you are just pushing hot header/engine compartment air across your radiator. I am much more of a "fan" lol of the standard VFR fan blade and a manual switch, that way you can turn it on early while stuck in traffic (pulling cool outside air across the radiator) and turn it off when you get moving, so there is no fan fighting against the natural flow of air. As far as you pushing coolant out of your reservoir: 1.) 245F is way too hot. You should have turned your bike off and waited 10 minutes after passing 230F. 2.) You could possibly have a bad head gasket. 3.) Hopefully you just have a bad radiator cap that cant hold pressure. Link to comment Share on other sites More sharing options...
iThinkergoiMac Posted July 14, 2016 Author Share Posted July 14, 2016 How does the radiator cap control the reservoir? They're on two different sides of the bike. I haven't looked into the thermostat, that's not a bad idea. However, if it was stuck open I shouldn't have any overheating issues since the coolant would constantly be flowing, and if it was stuck closed I wouldn't be able to keep the engine cool enough no matter what. It could be slow or something, but usually they get stuck open or closed. Still a good suggestion though, and I'll plan on looking into it. Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted July 14, 2016 Share Posted July 14, 2016 3 minutes ago, V-FORE said: I read through all the post about people switching fans and manual switches, then I realized that Honda has more research on all these issues Yes Honda did their research and went back to a conventional front mount radiator set up on the 8th gen. Link to comment Share on other sites More sharing options...
iThinkergoiMac Posted July 14, 2016 Author Share Posted July 14, 2016 2 minutes ago, CandyRedRC46 said: I am not a fan of the VTR fan blades, they work great while moving at 15mph+, but they are awful while stuck in traffic, because you are just pushing hot header/engine compartment air across your radiators. I am much more of a "fan" lol of the standard VFR fan blade and a manual switch, that way you can turn it on early while stuck in traffic (pulling cool outside air across the radiator) and turn it off when you get moving, so there is no fan fighting against the natural flow of air. As far as you pushing coolant out of your reservoir: 1.) 245F is way too hot. You should have turned your bike off and waited 10 minutes after passing 230F. 2.) You could possibly have a bad head gasket. 3.) Hopefully you just have a bad radiator cap that cant hold pressure. Hmmm, that's not a bad point. I still have the old fan blade. 1) The temperature on the dash doesn't start blinking until 250, so I didn't realize temperatures below that were dangerous. Why would Honda design their system to come on 10 degrees before the danger zone? Dumb. I'll keep that in mind for the future. 2) I don't think I have a bad head gasket. No white smoke or anything. 3) If the radiator cap can't hold pressure, how would that push coolant out the reservoir? Cooling systems are not yet my forte. Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted July 14, 2016 Share Posted July 14, 2016 2 minutes ago, iThinkergoiMac said: How does the radiator cap control the reservoir? They're on two different sides of the bike. I haven't looked into the thermostat, that's not a bad idea. However, if it was stuck open I shouldn't have any overheating issues since the coolant would constantly be flowing, and if it was stuck closed I wouldn't be able to keep the engine cool enough no matter what. It could be slow or something, but usually they get stuck open or closed. Still a good suggestion though, and I'll plan on looking into it. When pressure builds in the system (WHEN ITS HOT) the spring loaded radiator cap will let the coolant push through to the reservoir. You can still over heat an engine with a thermostat stuck open, it will just take longer to warm up. The thermostat's main function it to get the engine up to 170 as quickly as possible and keep it there. Once your coolant is above 180, the thermostat is not doing much. Link to comment Share on other sites More sharing options...
iThinkergoiMac Posted July 14, 2016 Author Share Posted July 14, 2016 1 minute ago, CandyRedRC46 said: When pressure builds in the system (WHEN ITS HOT) the spring loaded radiator cap will let the coolant push through to the reservoir. You can still over heat an engine with a thermostat stuck open, it will just take longer to warm up. The thermostat's main function it to get the engine up to 170 as quickly as possible and keep it there. Once your coolant is above 180, the thermostat is not doing much. OK, I see. Does the VFR use a standard size radiator cap? I can always order one off of Partzilla, but if I can just grab one at my local shop I'll do that. I'll find and test the thermostat as per the FSM as well. Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted July 14, 2016 Share Posted July 14, 2016 5 minutes ago, iThinkergoiMac said: Hmmm, that's not a bad point. I still have the old fan blade. 1) The temperature on the dash doesn't start blinking until 250, so I didn't realize temperatures below that were dangerous. Why would Honda design their system to come on 10 degrees before the danger zone? Dumb. I'll keep that in mind for the future. 2) I don't think I have a bad head gasket. No white smoke or anything. 3) If the radiator cap can't hold pressure, how would that push coolant out the reservoir? Cooling systems are not yet my forte. The 250F flashing light is to stop you from self destructing, 240F is still bad, even if not in the self destruct region. Ideally you want to stay below 230F. Above 230F is just putting unnecessary stress on your engine and cooling system. Look at the radiator cap, there is small line running from the cap to the reservoir. Link to comment Share on other sites More sharing options...
iThinkergoiMac Posted July 14, 2016 Author Share Posted July 14, 2016 1 minute ago, CandyRedRC46 said: The 250F flashing light is to stop you fro self destructing, 240F is still bad, even if not in the self destruct region. Ideally you want to stay below 230F. Look at the radiator cap, there is small line running from the cap to the reservoir. OK, good to know, I'll be sure to keep it from getting that hot again. I'm not interested in warping my engine. Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted July 14, 2016 Share Posted July 14, 2016 2 minutes ago, iThinkergoiMac said: OK, I see. Does the VFR use a standard size radiator cap? I can always order one off of Partzilla, but if I can just grab one at my local shop I'll do that. I'll find and test the thermostat as per the FSM as well. I think it is a standard 1.1 BAR or 15psi cap. If your coolant warms up to 170 relatively quick, then slowly goes up and down from 170 to 172 to 170 and then starts climbing again from there, it is probably okay, but definitely refer to the manual... Link to comment Share on other sites More sharing options...
iThinkergoiMac Posted July 14, 2016 Author Share Posted July 14, 2016 Just now, CandyRedRC46 said: I think it is a standard 1.1 BAR or 15psi cap. If your coolant warms up to 170 relatively quick, then slowly goes up and down from 170 to 172 to 170 and then starts climbing again from there, it is probably okay, but definitely refer to the manual... Yeah, it doesn't take long at all for it to warm up and then, so long as I'm moving, it stabilizes quite well. I'm going to look into replacing the radiator cap. Maybe it's just not sealing up correctly and allowing the system to kind of self-purge. Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted July 14, 2016 Share Posted July 14, 2016 that could be the case Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted July 14, 2016 Member Contributer Share Posted July 14, 2016 46 minutes ago, CandyRedRC46 said: I am not a fan of the VTR fan blades, they work great while moving at 15mph+, but they are awful while stuck in traffic, because you are just pushing hot header/engine compartment air across your radiator. Strangely I did the VTR mod & I measured the temps, it does NOT pull hot air, unlike the standard fan which fights normal airflow up to a certain road speed when on, rather than enhancing it. But beware a largish stone flicked into the fan will fold over the inner rad fins, so fit a stone guard. The VTR mod starts cooling at rest, then increases air flow through the rad as road speed builds. As an aside if the VTR didn't work, then neither would the 4th or 8th gen fans, as at a standstill they suck in air from the same place in front of the engine ! The VFR is one of the few where the rads are above rather than in front of the exhaust pipes, although only 50% of the engine heat comes out the front side, as the rear cylinders vent elsewhere. Also the side mounted rads don't tend to suffer stone hole damage as a few 8th gen owners have reported on this forum. They also make engine maintenance simpler as you can access the front head without removing/moving the rad ! For the OP, check the rubber seal on the rad cap, also check the lips on the rad cap, they should be square like an L if the upright of the L is the side of the cap, the lip underneath should not be bent down ! It does happen through ham fisted use, you should always push down on a rad cap before twisting ! to get past the retension tabs on the rad cap holes rim. Mine was like tahat when I got it, so I bent the lips back & fitted the cap 180 degreess around, by that I mean if you cap read the words on the cap right way up when stood to the right of the bike, remove cap & replace so the words are now upside down ! The rad cap controls the pressure of the fluid in the cooling system, there is a bleed hose below the rim that passes across the engine through the V to the left side mounted expansion tank. When cold the expansion tank should be filled to the LOWEST mark. The fluid in the expansion tank is there to act as a coolant to the expelled fluid/gas that comes from the rad cap pressure release, thus condensing it as it arrives in the tank. At maximum permitted temperature the tank should only reach the high mark, if it keeps rising there is a fault in the cooling system, as in your case. For everyone else a failed OPEN thermostat plays NO part in the cooling system. On the other hand a failed CLOSED thermostat will cook your engine in double quick time. If you want to check your thermostat as possibly stuck open, start bike & allow to reach 40c+ on the dash or just over 100f for you old worlders :) Put your hand on the top collector of the right rad through the air vent in the fairing, it should be at atmospheric temperature or just over as there is a small bleed hole in the thermostat. Once the temp guage shows 70C+ or 170F it should suddenly get hot as the thermostat opens & swaps the hot coolant for cold coolant from the left rad, after a few cycles the whole system will be at 70C+ then the thermostat will stay open unless the cooling air reduces the whole system to lower than its opening temperature, at which point it will start to close to restrict flow to control engine temp. Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted July 14, 2016 Share Posted July 14, 2016 The VTR fan may work okay in UK heat, but I tried it in central Florida and it would not drop the temperature when stuck in traffic, it would only maintain or even worse, slowly creep up. When moving above 15 mph and getting fresh air, the VTR fan blade worked great for me. But because I can get stuck in +100F traffic in central Florida, I had to put the factory fan back in, as that is the only way I wouldn't over heat in traffic. I feel like for a tight technical race course, where running 20-50 mph, the VTR fan would work awesome, but for struck in traffic, it only made my bike hotter. Link to comment Share on other sites More sharing options...
iThinkergoiMac Posted July 14, 2016 Author Share Posted July 14, 2016 If you could rig a way for the fan to work in one direction while stopped and then reverse while moving, all your problems would be solved! Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted July 14, 2016 Share Posted July 14, 2016 The fan is shaped to be most efficient spinning in a certain direction, but by all means, experiment, try different things. Link to comment Share on other sites More sharing options...
iThinkergoiMac Posted July 14, 2016 Author Share Posted July 14, 2016 Haha, I know. I wasn't seriously suggesting it. Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted July 14, 2016 Share Posted July 14, 2016 If God wanted us to use the metric system he would have given us 10 fingers. Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted July 14, 2016 Member Contributer Share Posted July 14, 2016 3 hours ago, CandyRedRC46 said: If God wanted us to use the metric system he would have given us 10 fingers. Ha Ha, I like it :) Maybe the 5th Gen & 6th gen are a bit different in fairing heat trap or dissipation. Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted July 14, 2016 Member Contributer Share Posted July 14, 2016 I'm pretty sure the cause of your overheating is indeed a faulty radiator cap. It is designed to allow the system to pressurise to 16psi or 1.1 bar, and that lifts the boiling point of a water-glycol mixture from 107C/225F to 130C/270F. Without the cap doings it's thing, you will be boiling the coolant within your engine, generating steam and blowing coolant out of the expansion tank. Link to comment Share on other sites More sharing options...
iThinkergoiMac Posted July 15, 2016 Author Share Posted July 15, 2016 I think that's the most logical conclusion. I've ordered a replacement cap. I'll be taking a trip before then, but seeing as how the bike stays at stable temperatures unless I get stuck I should be fine. Link to comment Share on other sites More sharing options...
CandyRedRC46 Posted July 15, 2016 Share Posted July 15, 2016 as long as you stay well below 225 you will be fine. if you get above 225, it will boil over and sky rocket. should be fine for highway. you hit traffic, youll need to shut it off, if you start approaching 225. Link to comment Share on other sites More sharing options...
iThinkergoiMac Posted July 15, 2016 Author Share Posted July 15, 2016 That's what I thought, thanks for the reassurance. I'm pretty good with most systems on my bikes (replaced the clutch no problem, rebuilt front forks on my Ninja 500, etc) but cooling systems are something I've not done much work with beyond replacing a radiator and a couple thermostats. This thread has helped a ton. Link to comment Share on other sites More sharing options...
Member Contributer jeffyjeff Posted July 15, 2016 Member Contributer Share Posted July 15, 2016 I use a STANT 11233 pressure cap. It fits my 5th gen perfectly and at around $8.00, its a fraction of the OEM part. I have used this cap successfully for years. It is a perfect fit replacement that is readily available at most auto parts stores. I get mine at Pep Boys. Link to comment Share on other sites More sharing options...
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