Rocket 3 Roadster Possibly Overheating?

Hey @R-III-R Turbo , I sent a private message because I didn’t wanna keep bothering people on this thread, but I’ll just say briefly here since I don’t think you got it:

You mentioned flipping over the expansion tank or just unclipping the hose that goes to the radiator. Is unclipping the hose easy? I just don’t wanna break the clip because that means I have to wait to get that part again. I figured clipping is probably the easiest thing to do because I don’t have to unbolt the expansion tank and flip it upside down so that way I don’t have to hold it.

Open the expansion tank fill cap and look inside your tank. Where the radiator hose attaches to the square block on top of the tank, inside the tank you should see a tube going from that block to the bottom of the tank. The rad hose from the rad cap goes to the top of the expansion tank (your photo confirms this). As long as the pressure in the tank is equal to the pressure in the radiator no coolant can flow back from the tank to the radiator (water doesn't defy gravity). The only fluid that might be present would-be fluid trapped in the hose below the top of the expansion tank and the radiator pressure cap. So, when you open the rad cap any fluid in that section of hose will drain out as an open path is available that wasn't before. To draw coolant out of the expansion tank against gravity you need a vacuum (basically you gotta suck the coolant out). This is done by thermodynamics and the volume compression of coolant in the radiator on cooldown. Coolant pushed into the tank as the engine heats up gets drawn back as it cools down. The pressure cap is a two-way valve that has a positive and negative opening pressure.

You can open that cap 30 times and every time you will get air in the system that will be pressurized out naturally if the cap works properly.
Now you can do.it 30 times if you like working on your bike and practice makes better mechanics but what i would do at this time is just do the bleed one more time with out touching anything else on the bike.
Ride it and if you sit there long enough the fan will come on and if you keep sitting the heat light will come on doesn't mean that anything is wrong you just need to drive to cool it off

atomsplitter said:

Open the expansion tank fill cap and look inside your tank. Where the radiator hose attaches to the square block on top of the tank, inside the tank you should see a tube going from that block to the bottom of the tank. The rad hose from the rad cap goes to the top of the expansion tank (your photo confirms this). As long as the pressure in the tank is equal to the pressure in the radiator no coolant can flow back from the tank to the radiator (water doesn't defy gravity). The only fluid that might be present would-be fluid trapped in the hose below the top of the expansion tank and the radiator pressure cap. So, when you open the rad cap any fluid in that section of hose will drain out as an open path is available that wasn't before. To draw coolant out of the expansion tank against gravity you need a vacuum (basically you gotta suck the coolant out). This is done by thermodynamics and the volume compression of coolant in the radiator on cooldown. Coolant pushed into the tank as the engine heats up gets drawn back as it cools down. The pressure cap is a two-way valve that has a positive and negative opening pressure.

Click to expand...

Dude will you sit back down, please.
The question was directed at me yet you felt the need to answer it for some reason.
Like a previous question I asked of the OP, you felt the need to step in to respond. Why?
I've replied and am guiding the man back to business.

This thread is already 10 pages deep, mostly noise; the problem is a simple one.
And was solved 4 posts in with the trapped air, faulty rad cap diagnosis.

Too many voices here (and also misinformation*) has the man distracted and confused, trying to learn a basic bit of bike maintenance.
Thermodynamics and volume compression.. like honestly, what the eff.

*Example. That tube on top of the exp tank with the square block is the overflow tube. Carries overflowed coolant from exp tank away to ground.
The tube that goes from the bottom of the exp tank is what connects the exp tank to the rad.
There's no tube going from inside the top of the exp tank down to its base...

His exp tank emptied and the coolant all flowed out when rad cap was initially removed, because gravity.

I understand you're trying to help. Thank you - and I'm not criticising that.
But too many cooks do spoil the broth despite best intentions, it's worse when someone is rowing against another.
This is why I'm challenging you for this behaviour.

Thanks R-IIIR Turbo, I stand corrected. Looked up the particular part and you are spot on. Carry on, I will sit down.

Good news everyone! I actually did it, as simple as it is, everything that has happened, happened for a reason, this whole process has made me more confident with my bike as a “junior mechanic”.

What I like about this community is everyone’s eager to help, very much like in NYC when someone asks for directions. You got 5 different people giving you different directions to get to the same place, all go about it differently but the result is the same, and they all want you to get to where you need to go, very much like my situation here, believe it or not.

@atomsplitter thank you for teaching me the physics, even though it was overwhelming I was still curious, and wish I had your knowledge.

@R-III-R Turbo i appreciate you listing the exact thing I needed to do from the start, but in a way I’m glad it went as long as it did because it allowed me to do my own research. And I thank everyone for chiming in from time to time. Too many voices is to be expected in forums like these, it’s all love from my standpoint.

Now, to tell you what happened to conclude this journey:

I went back to thread #36, and followed it religiously. I don’t think I’ll ever forget the process.

1) I loosened the bleed bolt first until coolant came out. Once it stopped, I tightened it back up. Manual says 10nm so you tighten it to that.

2) I leaned the bike to the right, and put a piece of wood underneath the kick stand so it can be more upright.

3) I took off the bear claw, and I took out the first bolt holding the expansion tank, and leaned it all the way down to its side to the point where coolant wouldn’t add anymore to the radiator once I took the rad cap off (I knew this before this step because I took off the rad cap, and when I leaned the expansion tank all the way to its side, coolant drained fast, because the expansion tank isn’t sitting upright anymore, essentially it’s upside down-ish)

4) I took off the rad cap, and filled it up to the filler neck (the brim).

5) This is where it gets fun! With the rad cap still off, I leaned the bike to the left and right a couple of times, and while looking at the opening of the radiator where the cap goes, I saw bubbles starting to surface to the top and disappear. It was the craziest thing. I did this for about 3 minutes-it was a workout.

6) After leaning the bike, coolant wasn’t at the brim anymore , so I tapped it off with more coolant. Put the rad cap back on, expansion tank upright again, filled the expansion tank just at the max mark. Bear claw back on, cleaned off the extra coolant that spilled everywhere cause I’m clumsy.

7) I turned the bike on, had it idle for about 5 minutes before taking off to work.

Conclusion:

I believe the bike is doing ok now, it’s a hot day today, and my leg was a bit hot, BUT NOT the point where it was painful (yes it was getting that hot before it was bad). I believe the temps are normal. Once I got to stand still traffic in the hot sun and even in the tunnel, tank
/bear claw was very hot, but the radiator was not blowing hot air to my leg, it was normal. Once I started riding temps seem to chill.

I checked the temps after my ride on this hot day, it was about 114 to 115c, when it got this hot before it was a cool night and my leg was burning, but now it’s a hot day, and my leg is not flaming on .

All in all, I think I’m at a good place. So…yeah that’s pretty much it.

One thing I noticed is that the rim around the bleed bolt was orange even before I loosened it, not sure if that’s a sign off the bleed bolt going bad when I had problems before with the bad cap, I did get a replacement bolt just in case it dropped, never to been seen again. So if I want to I could replace the bolt, but it’s not leaking so I think I’m ok.

Again, thank you all