The Mystery of the Disappearing Coolant

[rjmorel]

I got tired of removing the plastic covers when I put in coolant so I put this funnel extension gizmo together. Now to add coolant ,I just reach in and pop the top of the overflow bottle hose off the radiator end with some pliers to remove the hose clamp and put the white end of the funnel extension into the overflow hose and add coolant. Don't have to take any thing off that way or remove the overflow bottle cap.
Spud my RX3 has 4500 miles on it and the coolant has gone down a little when out on long rides. I carry a bottle of coolant with me but now I am confident its not needed as the coolant takes a lot of miles before it gets very far down in the overflow bottle. I'll try it out this coming week at the Sound Rider Rally in the Gorge .rj

[Weldangrind]

Originally Posted by SpudRider

I just changed the engine oil several days ago, when I passed 8,000 miles on the odometer. No, I did not notice any 'milkshake' on the underside of the oil filler cap. The bike runs cool, the engine runs great, the used engine oil looks wonderful, et cetera. I can't find any coolant leaks, and I don't believe the engine is consuming any coolant.

it sounds like all systems are go. Enjoy your bike.

[Weldangrind]

Originally Posted by SpudRider

You have an interesting perspective on this matter. As always, thanks for your input, Kat.

I do know the overflow bottle will top off the radiators on my Honda CRF250X. If the overflow bottle can't top off the radiators, why do the manufacturers always tell you to fill the overflow bottle with a certain amount of coolant?

If you don't have any coolant in the overflow bottle, you risk drawing in air when the system cools. Think of how you keep a hose in a bottle of brake fluid while bleeding brakes.

You don't need much fluid; just enough to keep the hose end immersed. Is there a min/max indication?

[Jay In Milpitas]

While on this subject, has anyone measured the full capacity of that little bottle? It's not very big and looks to be thick walled.

I'm guessing less than a cup (8oz) total. So about twice my bladder capacity.

[AZRider]

Spud, sorry I missed your water pump comment in your first post. I checked my cap for tightness and it's fine. I would not leave the overflow tank dry, as it needs a prime to function properly, however, as long as one regularly checks the fluid level in the radiator, the overflow tank is superfluous.

[roots]

Hey Spud, my cap has been an issue since the beginning. It pops off easily when tightened. I get it snug, not too tight, and then I find it popped later. I assumed my periodic coolant loss was due to spillage. The last time I was refilling I did notice a tiny vent hole in the cap, so even if the cap is fully sealed the system should be able to vent through the hole. My cap threads appear to be fine when I look at them, so I have been suspecting the bottle threads are "bad". I just haven't had the time to pursue it further. I switched from filling the "overflow" bottle through its cap to filling through the radiator cap. If you have the bike on the side stand and fill it slowly with a funnel, it overflows into the bottle just before it would overflow out of the radiator (I picked up that technique somewhere from another RX3 owner). I can unscrew the radiator cap without removing any panels, so that seems to work better for me.

[SpudRider]

Originally Posted by Huck369

Just went out and checked mine, and it seems to seal good, and tight (I didn't "Try" to over tighten it, but what I felt was good amount of torque for a plastic bottle) so maybe yours is bad Spud...

Originally Posted by NoVa Rider

Spud, the cap on my bottle tightens normally, it doesn't skip threads. I actually loosen the left side radiator so I can unhook the bottle and unscrew it, leaving the cap in place. I had no problems last week when I did this to bring the coolant up to the "full" mark on the bottle. It screwed back on correctly to a normal "tight" feel.

I think it's likely yours was overtightened at the factory and stripped. I'd try a new cap and bottle from CSC.

BTW my coolant level (in the bottle) seems to have stabilized at about half-full.

Thank you, gentlemen. I will make the call to CSC tomorrow, and request a new coolant overflow bottle, with cap.

[SpudRider]

Originally Posted by rjmorel

I got tired of removing the plastic covers when I put in coolant so I put this funnel extension gizmo together. Now to add coolant ,I just reach in and pop the top of the overflow bottle hose off the radiator end with some pliers to remove the hose clamp and put the white end of the funnel extension into the overflow hose and add coolant. Don't have to take any thing off that way or remove the overflow bottle cap.
Spud my RX3 has 4500 miles on it and the coolant has gone down a little when out on long rides. I carry a bottle of coolant with me but now I am confident its not needed as the coolant takes a lot of miles before it gets very far down in the overflow bottle. I'll try it out this coming week at the Sound Rider Rally in the Gorge .rj

Thanks for posting the good information, George. Based upon the replies of Huck and NoVa, I'm pretty sure my coolant overflow bottle and cap are damaged. I'm hoping a new cap and bottle will fix the problem.

[SpudRider]

Originally Posted by Weldangrind

If you don't have any coolant in the overflow bottle, you risk drawing in air when the system cools. Think of how you keep a hose in a bottle of brake fluid while bleeding brakes.

You don't need much fluid; just enough to keep the hose end immersed. Is there a min/max indication?

Yes, the bottle has min/max markings.

[SpudRider]

Originally Posted by Jay In Milpitas

While on this subject, has anyone measured the full capacity of that little bottle? It's not very big and looks to be thick walled.

I'm guessing less than a cup (8oz) total. So about twice my bladder capacity.

I'm thinking we are about the same age, Jay.

[SpudRider]

Originally Posted by AZRider

Spud, sorry I missed your water pump comment in your first post. I checked my cap for tightness and it's fine. I would not leave the overflow tank dry, as it needs a prime to function properly, however, as long as one regularly checks the fluid level in the radiator, the overflow tank is superfluous.

I agree. As Weld mentioned, you certainly need a little coolant in the bottom of the bottle to prime the pickup hose, or you will draw air into the radiators. That's why the bottle has min/max markings.

Thanks for verifying the tight fit of your bottle cap. You have further confirmed my suspicion that I have a bad bottle and cap.

I also agree with you comment regarding checking the coolant level in the radiator. However, I can't unscrew the radiator cap without removing the fairing, so it is much easier to check the level of the coolant overflow bottle.

The coolant level in my radiator remains topped off, so I must assume my overflow bottle and cap are damaged, don't seal, and the coolant is evaporating from the overflow bottle. I will either confirm, or refute this theory after I receive a new overflow bottle and cap from CSC.

[SpudRider]

Originally Posted by roots

Hey Spud, my cap has been an issue since the beginning. It pops off easily when tightened. I get it snug, not too tight, and then I find it popped later. I assumed my periodic coolant loss was due to spillage. The last time I was refilling I did notice a tiny vent hole in the cap, so even if the cap is fully sealed the system should be able to vent through the hole. My cap threads appear to be fine when I look at them, so I have been suspecting the bottle threads are "bad". I just haven't had the time to pursue it further. I switched from filling the "overflow" bottle through its cap to filling through the radiator cap. If you have the bike on the side stand and fill it slowly with a funnel, it overflows into the bottle just before it would overflow out of the radiator (I picked up that technique somewhere from another RX3 owner). I can unscrew the radiator cap without removing any panels, so that seems to work better for me.

It appears you also have a bad overflow bottle. Thanks for mentioning the vent hole in the bottle cap.

I see you are using RJ's method of filling the overflow bottle. If you don't need to remove the fairing to unscrew the radiator cap, you must have small hands.

[SpudRider]

Originally Posted by stevecast

Only one place for fluid to go when you overfill an overflow bottle "hence the name". More than likely, as the fluid expands from heat "while running", the excess is being forced out the drain tube. The overflow bottle should never be more than 1/4 to 1/3 full. You have to allow for fluid expansion due to heat transfer. Stop filling the bottle, and you'll be fine, so will your bike.

Welcome, Steve. Do you own an RX3?

The overflow bottle has min/max markings. Therefore, when we say 'fill' the overflow bottle, we realize we are supposed to add coolant to a level between the two markings.

[Weldangrind]

If you translate that to car language, max becomes full hot, and min becomes full cold.

[SpudRider]

Originally Posted by Weldangrind

If you translate that to car language, max becomes full hot, and min becomes full cold.

Thanks, Weld. Now I better understand what Steve was saying.

"Full Hot" and "Full Cold" are much more descriptive labels than "Min" and "Max." The "Min" term seems to indicate the coolant is disappearing to a certain minimum value, rather than reaching its natural, maximum level, when the coolant is cold.

The "Min" marking on the coolant overflow bottle of the RX3 is very near the bottom of the bottle. Therefore, one should only see about 1-inch of coolant in the bottle when the engine is cold. The coolant might rise to the "Max" level when the radiators are very hot, but it will naturally drop to the "Min" level when the bike is parked overnight, et cetera.

If one fills the overflow bottle with coolant above the "Min" level when the engine is cold, it will merely be vented out the cap when the coolant temperature rises.

Also, as AZRider stated, the main task is to confirm the radiators are full. If the radiators remain full, one shouldn't be concerned if the coolant in the overflow bottle reaches the "Min" level when the engine is cold. Indeed, this is the normal operation of the "overflow" bottle.

Thank you, gentlemen.