Possible head gasket failure or something else?

[Gearhead24]

Hello,
Throughout the whole summer my cooling system has been temperamental. Whenever I have a fun ride and park it coolant would come out of the overflow tube. How that I have my reservoir hooked up I’m noticing it come from the exhaust. I’ve got the 6 into 6 which are solid with no joints or holes in it and yet coolant is coming out from where the pipes bend up into the straight. I don’t know much about cooling systems but while idling and warm I pulled the radiator cap and fluid shot out, that was expected. What I didn’t expect was coolant to come back up on every slight twist of the throttle. Bike has been running great with no performance issues, but the right bank seems to be drinking coolant. I know the shop manual bleed procedure says to fill the radiator to the top and idle the bike for a few minutes giving it throttle here and there. I’ve done that multiple times and no luck. I’m sure the temp sensor is factory original so that might be due for a change. I know head gasket failure is rare on these bikes so I’m hoping it’s not that, if it is it’s not the end of the world since they’re easy to do

[WintrSol]

So, is the coolant reservoir level rising when the engine is hot, then returning to the level it should have as the engine cools? I ask, because the vent/overflow of mine was plugged by a bug, causing similar symptoms.
Are you sure there is coolant coming out the exhaust? Is it green and smell of coolant? If not, it could just be normal condensation escaping through the small drain holes.

[98valk]

coolant level is checked by the indications on the coolant overflow bottle.
coolant is only added as needed to the overflow bottle to the correct level.
and never add coolant directly into the radiator.

[Chrisj CMA]

Sounds like a bad thermostat

[Gearhead24]

So, is the coolant reservoir level rising when the engine is hot, then returning to the level it should have as the engine cools? I ask, because the vent/overflow of mine was plugged by a bug, causing similar symptoms.
Are you sure there is coolant coming out the exhaust? Is it green and smell of coolant? If not, it could just be normal condensation escaping through the small drain holes.

I am positive it’s coolant, it’s neon green and a lil sweet lol. I haven’t taken the side cover off yet to view the reservoir, probably should have done that. When I got to class this morning I saw the green drips on the outside of the exhaust and have been seeing puddles of various size randomly from the same area. All I did when I got home was check to see if there was an active leak, and there was smoke coming from that bend in the pipes. After that I popped off the cap and coolant shot all over the place, tried to rev the bike and the slightest throttle would send coolant all the way out the top.
I’m busy today so I didn’t have much time to run other tests, but tomorrow or later today I’ll pop that side cover and monitor the reservoir. Is there any way to replace the thermostat without taking the carbs out? I literally just cleaned and put them back on two days ago

[Chrisj CMA]

I think you can change the thermostat by removing the radiator

[WintrSol]

clean the exhaust well, so the next time, you can check to see if the coolant is coming from them, or have a trail towards the front. It could be dripping out of the radiator and being blown back.

[Mooskee]

I think you can change the thermostat by removing the radiator

That is how the manual describes it. I think you need a new pipe O-ring as well when you change the thermostat.

[Gearhead24]

I found out where the coolant is coming from and it’s my own damn fault for not setting things up 100% right. The hose that comes out of the bottom of the reservoir apparently was going all the way across the clutch cover and ended just above the right side exhaust right at the bend. So coolant was boiling over and going into the reservoir, and as that filled up too high it would flow out the line and onto the exhaust. No doubt my thermostat inside is bad so I will be replacing that.
Now I know you’re not supposed to do it in order to maintain operating temps, but would it be cataclysmic if I straight up removed the thermostat temporarily? The only results I got from a quick google were regarding vehicles with pcm controlled everything saying the computer would treat it like a cold motor. Since these don’t do that could I be fine for a week or two with mostly under 10 mile rides and no thermostat?

[Chrisj CMA]

I found out where the coolant is coming from and it’s my own damn fault for not setting things up 100% right. The hose that comes out of the bottom of the reservoir apparently was going all the way across the clutch cover and ended just above the right side exhaust right at the bend. So coolant was boiling over and going into the reservoir, and as that filled up too high it would flow out the line and onto the exhaust. No doubt my thermostat inside is bad so I will be replacing that.
Now I know you’re not supposed to do it in order to maintain operating temps, but would it be cataclysmic if I straight up removed the thermostat temporarily? The only results I got from a quick google were regarding vehicles with pcm controlled everything saying the computer would treat it like a cold motor. Since these don’t do that could I be fine for a week or two with mostly under 10 mile rides and no thermostat?

I can’t make heads or tails about what you just posted. If you misrouted a coolant tube then fix that. If it’s a bad thermostat get a new one. I can’t give you an answer to your question

[Gearhead24]

Hose is rerouted, but it shouldn’t be dumping coolant out every time I ride either so a new thermostat is in order. I was wondering if it would be fine to temporarily run without a thermostat while I wait for a new one or if I should park it until the new part comes in. Most of my rides are short distance

[Chrisj CMA]

I’m nit sure if any harm would come to it. I wouldn’t do it. I’d wait.

[98valk]

Hose is rerouted, but it shouldn’t be dumping coolant out every time I ride either so a new thermostat is in order. I was wondering if it would be fine to temporarily run without a thermostat while I wait for a new one or if I should park it until the new part comes in. Most of my rides are short distance

park it.
aluminum gives off heat faster than cast iron. I say that since I've read that cast iron engines running at water temp of 180F and less have greatly increased wear.

[Gearhead24]

Pulled the old thermostat and tested it in a pot of water at 180 and it opened up so that works, coolant is clean as well. I found a thread here that had a generic parts list and picked up a 180 thermostat and gasket that both fit snug inside the housing expecting to use it. Will put the old tstat back in and keep the new setup with me along with the tools to swap it out just in case.
Maybe the system was t properly bled I’m not sure but will make sure of it tonight

[John Schmidt]

You have the old t'stat out so why put it back in, just install the new one since you're that far along. Also, keep in mind the location of the little hole in the outer edge of the housing, I don't recall if it goes to the front or rear but believe it's given in the shop manual. Re. the original question, watch to see if you have a hose collapsing when in operation and hot.

[Gearhead24]

The only reason I didn’t swap the new one in is that while it fits inside the housing, the stat looks quite different from the old one. I know they’re different applications but the difference in looks was enough to make me wary. Didn’t see anything in the manual about stat positioning but I also miss 90% of details. Took the bike out for a hard run, 30 minutes of 85+ and the motor stayed cool. When I parked the bike I couldn’t see any drop or smoke, checked it an hour later and still no drips or puddles. My issue all along was an improper bleed and me being an idiot, what else is new.
Thanks for the help guys, I always appreciate the input

[98valk]

FYI.
OEM is best. its a high flow unit and designed for best operation of an aluminum engine with al heads.
its the same thermo used in a GL1500 Goldwing.
the oem thermo opens at 176-180 same as any 180 thermo and it is fully open at 203, same again as any 180 thermo. these #s are from the tech manual. just about all thermo's are fully open 20 degrees more than their temp, i.e., 160 is fully open at 180. if an engine wants to run at 210 it will do that no matter if a 160 or 180 thermo is installed.
plus the oem is high flow with a larger opening then off the shelf so called high flows at least the ones I checked.