Member Contributer Duc2V4 Posted July 8, 2015 Member Contributer Share Posted July 8, 2015 So here's the story. Last month my '09 leaked coolant when I was out and about. I thought it was from waiting to enter the clients gate at such a steep incline with the motor running. It was a very steep angle and it took a few minutes for the gate to open and even the ride to the top of the hill was really steep. So I didn't think too much about it, but I monitored the temps on the way home and everything seemed to be fine. That being said, just to be sure I flushed/filled the cooling system, burped it and everything seemed to be back to normal. Even my ride last Friday up in the Angeles Forest was uneventful. That was until this morning! I had to ride into LA from Orange County, roughly a 30 mile commute from where I live, albeit with some light traffic. When I got to my job site, the person at the parking lot pointed to my bike and said "You have a leak!" WHAAAT?!, Sure enough the bike was leaking coolant, rapidly I might add. I quickly switched from ambient temperature mode to engine temp and the gauge read 233F. Not that I haven't been at that or slightly above that before. In fact, on our VFRD trip up in King's Canyon 2 years ago had many of us at ~238F with no spillage of coolant. I parked, did my job and similar to last month monitored the temps on the way home, no hotter that 182F while on the freeway and surface streets. Once I got to my complex, I decided to see what the issue is, and at first I thought it was the fan or fan switch as while I did a slow circle inside the complex, I let the temps rise to 230, and low and behold no fan! OK so there's the issue right?...Not exactly, since my coolant level was down so low, I don't think there was enough in the system to allow the fan switch to register the coolant temp. I tested this theory by filling up the coolant level again and double checking that the fan worked i.e. Shorting the fan switch lead to ground, so it wasn't the fan for sure. So with coolant filled up, wiring put back to normal, off I went. Slowly I was able to get the temp to rise to at least 220F and sure enough the fan kicks on, I let it rise to about 230 and then I shut off the engine but left the ignition on and let the fan go for a while and the temp dropped pretty quickly. Started it back up and went home. So based on all of this, the only other suspects I can point to would be the thermostat, but that actually seems to be working so far. So the remaining suspect has to be the radiator cap. I do not have a radiator testing kit, but since all other things seem to be normal, I have to go with the process of elimination. It has to be the radiator cap, would you agree? Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted July 8, 2015 Member Contributer Share Posted July 8, 2015 My bet is the thermostat, every time I have been around a failing cap you could smile antifreeze. Roll On VFRD .. Link to comment Share on other sites More sharing options...
Member Contributer Duc2V4 Posted July 8, 2015 Author Member Contributer Share Posted July 8, 2015 No other signs of thermostat trouble have shown up, gas mileage is good, warm up and cool down seem to the norm. Apart from pulling the tstat and testing it, which means one might as well replace it for good measure anyway, is there any other test or signs of a tstat going out? Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted July 8, 2015 Member Contributer Share Posted July 8, 2015 Not to advocate throwing parts at something, but of the two, the cap is cheap and far easier to replace. So maybe swap it for the one from your 5th gen and see what happens. If the problem surfaces there you've found it. Since I installed a fan override switch on my 6th gen I've been able to largely avoid situations where the engine gets extremely hot from idling or pulling a grade at low speeds. I just have to remember to switch it back to normal once I get moving! :blush2: Link to comment Share on other sites More sharing options...
Member Contributer HighSideNZ Posted July 8, 2015 Member Contributer Share Posted July 8, 2015 I had a situation where whilst running my bike on a dyno a pool appeared under it on the dyno and room floor. Shutting it off and investigating it seemed to be coming from around the outlet hose on the pump. On further investigation I found it was the pump shaft seal gone. There are 2 little holes in the pump body, on the nose that goes in to the engine casing. These are there to allow coolant that has got past the face seal to leak out to the real world and not fill the bearing with coolant and flush the grease out. Put it on the centre stand, pull the fairing and run it. Lay under it and check that there is no coolant running down the hoses from the pump. If there is, wipe it away and keep checking. If it continues, the pump face seal is shot. Link to comment Share on other sites More sharing options...
Member Contributer Duc2V4 Posted July 8, 2015 Author Member Contributer Share Posted July 8, 2015 Not to advocate throwing parts at something, but of the two, the cap is cheap and far easier to replace. So maybe swap it for the one from your 5th gen and see what happens. If the problem surfaces there you've found it. Since I installed a fan override switch on my 6th gen I've been able to largely avoid situations where the engine gets extremely hot from idling or pulling a grade at low speeds. I just have to remember to switch it back to normal once I get moving! :blush2: I was thinking the same thing earlier, but figured I'd test the fan and switch first. Might try and swap rad caps tomorrow and see what happens. My current mileage is at 38.5k so it might be worth doing the tstat change now, maybe even the stator for good measure! Link to comment Share on other sites More sharing options...
Member Contributer Duc2V4 Posted July 8, 2015 Author Member Contributer Share Posted July 8, 2015 I had a situation where whilst running my bike on a dyno a pool appeared under it on the dyno and room floor. Shutting it off and investigating it seemed to be coming from around the outlet hose on the pump. On further investigation I found it was the pump shaft seal gone. There are 2 little holes in the pump body, on the nose that goes in to the engine casing. These are there to allow coolant that has got past the face seal to leak out to the real world and not fill the bearing with coolant and flush the grease out. Put it on the centre stand, pull the fairing and run it. Lay under it and check that there is no coolant running down the hoses from the pump. If there is, wipe it away and keep checking. If it continues, the pump face seal is shot. From what I saw this morning, it was definitely from the reservoir overflow tube. I'll double check though. Thanks for the tip. Link to comment Share on other sites More sharing options...
zenkai988 Posted July 8, 2015 Share Posted July 8, 2015 I'd say it's the radiator cap malfunctioning. It can't hold more than atmospheric pressure, so that all the hot coolant goes in to the reservoir and overflows. As the engine/coolant cools off, there is air in the system and the engine overheats. Link to comment Share on other sites More sharing options...
Member Contributer HighSideNZ Posted July 8, 2015 Member Contributer Share Posted July 8, 2015 I thought the overflow as well but the problems is that ALL of the breather/overflow tubes exit the bike just below the water pump! Link to comment Share on other sites More sharing options...
wera803 Posted July 8, 2015 Share Posted July 8, 2015 All of the thermostats I have heard of that failed on these bikes are in the open position, not closed. I guess it is possible for it to stick closed, just doesn't seem common with these bikes. Link to comment Share on other sites More sharing options...
Member Contributer Mohawk Posted July 8, 2015 Member Contributer Share Posted July 8, 2015 Check the rad cap, clean it & check the lips have a full bend ! Turn it through 180 degrees & try again. There should NEVER be any fluid loss from a cooling system, that's why it has an expansion tank, the tank is sized to hold the maximum expected expansion. Please ensure you only fill it to the minimum line, Fluid should never be sucked into a cold system, which is how it has to be for you to fill it ! At normal temps when the fan engages, the expansion tank should not exceed the maximum line, if it does then something is over pressurising the coolant system. It's rare for a thermostat to fail closed, but if it does its permanent, it can only fail closed because it has had a loss of expansion wax or oil, once this occurs the thermostat will remain closed, so you will over heat all the time. If the thermostat fails open, it does so when the spring fails which closes it, without the spring pressure, even at ambient temps the wax/oil will fully open the thermostat. So not likely to be the thermostat. If the fluid is coming out of the overflow from the expansion bottle, either its over full, I saw a pic on here of a cold one that someone had filled to the brim ! The rad cap is NOT functioning properly, so allowing excess fluid past, or the engine is over pressuring due to Fan malfunction, its there to stop the system getting any hotter & thus increasing the pressure, or you have a head gasket leak, these can be intermittent. I had a car once that took 6 weeks to fully develop its head gasket leak, was intermittent at first. Or as HighsideNZ, said you are just assuming the leak is from the overflow, it could be the hoses, or hose clamps & I've seen some very rusty clamps on old bikes that were used in the wet a lot ! Link to comment Share on other sites More sharing options...
Member Contributer Duc2V4 Posted July 8, 2015 Author Member Contributer Share Posted July 8, 2015 Check the rad cap, clean it & check the lips have a full bend ! Turn it through 180 degrees & try again. There should NEVER be any fluid loss from a cooling system, that's why it has an expansion tank, the tank is sized to hold the maximum expected expansion. Please ensure you only fill it to the minimum line, Fluid should never be sucked into a cold system, which is how it has to be for you to fill it ! At normal temps when the fan engages, the expansion tank should not exceed the maximum line, if it does then something is over pressurising the coolant system. It's rare for a thermostat to fail closed, but if it does its permanent, it can only fail closed because it has had a loss of expansion wax or oil, once this occurs the thermostat will remain closed, so you will over heat all the time. If the thermostat fails open, it does so when the spring fails which closes it, without the spring pressure, even at ambient temps the wax/oil will fully open the thermostat. So not likely to be the thermostat. If the fluid is coming out of the overflow from the expansion bottle, either its over full, I saw a pic on here of a cold one that someone had filled to the brim ! The rad cap is NOT functioning properly, so allowing excess fluid past, or the engine is over pressuring due to Fan malfunction, its there to stop the system getting any hotter & thus increasing the pressure, or you have a head gasket leak, these can be intermittent. I had a car once that took 6 weeks to fully develop its head gasket leak, was intermittent at first. Or as HighsideNZ, said you are just assuming the leak is from the overflow, it could be the hoses, or hose clamps & I've seen some very rusty clamps on old bikes that were used in the wet a lot ! Thanks Mohawk. I will double check the area NZ mentioned as well as the clamps and such, but a cursory inspection everything looks clean. My observation after doing the test to see if it was the fan switch, I could clearly see the reservoir starting to fill up but no leaking as I stopped the engine and let it cool off.I'm going to swap the rad cap off the 5 Gen today and give it a whirl. By my observation and testing, it does feel to me it's the rad cap. Link to comment Share on other sites More sharing options...
Member Contributer Switchblade Posted July 9, 2015 Member Contributer Share Posted July 9, 2015 The 03 did a bottom hose clamp that started to leak after heating up. I could smile and it took awhile to find . Link to comment Share on other sites More sharing options...
Member Contributer Duc2V4 Posted July 10, 2015 Author Member Contributer Share Posted July 10, 2015 It was the rad cap, or so it seems. Rather than swapping caps off the 5 Gen, I just went and bought one. Quick, easy and I was pretty sure it was the culprit. Besides, if it turned out to be the thermostat I would have replaced both anyway. I tried for at least 40-50 minutes of street riding to get the temp above the 220 mark. It only went there twice (223 & 225) but quickly came down when the fan came on. I'll monitor it just for good measure. @Mohawk. The Honda manual seems to contradict what you said about filling the reservoir. You said to fill to the lower level, HSM says fill to the upper level. I know I followed the manual the previous coolant change so I did the same this time as well. We'll see how it goes I guess. Cheers Link to comment Share on other sites More sharing options...
Member Contributer Cogswell Posted July 10, 2015 Member Contributer Share Posted July 10, 2015 It's great when an easy fix solves the problem! Link to comment Share on other sites More sharing options...
Member Contributer Terry Posted July 10, 2015 Member Contributer Share Posted July 10, 2015 I'm a bit late to this party (story of my life...) but checking for a stuck-open thermostat is pretty easy. Start the bike from cold and keep your hand on a radiator. If the 'stat is stuck the rad will start to heat up before the bike hits around 70C (which is when the tstat should start opening). If it stays cold, then suddenly gets hot when the engine gets to about 70 then all is well. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
Member Contributer paulmeisterpk Posted July 10, 2015 Member Contributer Share Posted July 10, 2015 Just to add, I'm with Mohawk that the expansion tank should be filled to the lower level when cold. Link to comment Share on other sites More sharing options...
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