Losing coolant?

I seem to be losing coolant from somewhere on my 03. Between August of 2013 and May 2014 the level on the overflow went from the high mark to the low mark. The bike sat for most of that time too (November-March).

No visible leaks either.

Any ideas?

How can I pressure test?

Unrelated but I seem to be missing a charcoal cannister hose?




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Did you do both readings when the motorcycle was cold?

 

Yes


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The expansion tank suffers from evaporation loss. This may not be the full story, but in 4 months I lost from the high line to low line and no leaks. Added to about halfway between the lines for good measure and thats where its stayed.
If you cant find a leak on the engine and your exhaust is fairly dry (burning gasoline makes water as a byproduct, so expect a little wetness but no a lot) then my bet is just normal evaporation.

As for the canister, only two hoses are connected. One big one, one small one. The small one goes to the gas tank breather, the big hose goes to the purge solenoid by the airbox. Thats all thats there, the other large hole is the evap can breather. This allows the can to be purged.

Hope that helps.

 

Yeah big time zen biker. I was really worried. What you lost in 4 months I lost in 9.

I'm not used to water cooled bikes. Last long term bike I had was a 70s cb750.


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its part of the bi annual fairing removal. oil, coolant, cleaning, electrical check.

 

I'm out of coolant again. So just shy of 4 months and my reservoir is empty again.

Bike sits covered outside in northeast. Is this normal evaporation?

If not how can I check or test my radiator cap?


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I think coolant levels would be more dependent on how much you ride it and how hot it gets.

I have an '03 and it doesn't lose that much, better now I have manual fan switch.

Is radiator cap original? May you need to invest in a new one. If it is not holding pressure, coolant will boil at lower temperature.

Honda shows a pressure tester in the manual, but you could probably buy 10 caps for the price of the tester.

 

Are we talking coolant in the SYSTEM or only in the overflow reservoir?

you can get a coolant pressure tester for around $50. It will tell you right away if you have a leak in the cooling system. If it's only the reservoir, I'd not sweat it...look for a cheap used one of ebay, but don't be in a hurry.

On second thought, I think I have a spare one lying around you can have if you find it's your reservoir.

 

I haven't been riding it much. I have a used reservoir on the way from eBay for 15 bucks shipped. Maybe I really should just spend another 20 and get a new radiator cap too.

I have to check if it's system or just overflow that's losing it.


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Something to think about, water evaporates but not necessarily the antifreeze so when you top off the over flow you may want a bit more water +50/50 mix. You don't want above 60/40 antifreeze to water ratio and you don't want below 60/40 water to anti freeze if you are in a freeze zone. 60/40 water to anti freeze probably isn't a bad thing in the desert and hot south tho.

Can't hep with he leak since it is sitting. Riding means the hoses and joints are under pressure but sitting engine off no pressure so I'd guess evaporation or you were low and when the bike cooled after you last rode it, it sucked up antifreeze from the over flow tank which is what it is supposed to do. If this is the case, check the screws on the hose clamps and joints there are some on the right near the thermostat as well as the couplings by the oil filter

Depending on how long it's been since your last coolant swap (over two years) you may just want to drop $30 and do a swap. Then keep an eye on it.

 

But is it normal to evaporate an overflow worth of coolant in 4 months?

Or should I only be thinking there is a leak somewhere I must find (or a defective radiator cap)?


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NO, not normal.

A defective radiator cap would most likely mean your overflow would be FULL.


My best guess is you have a hairline crack in your reservoir. Have you checked the actual radiator to see if it's full?

The only other thing that would cause coolant loss with no visible evidence would be a leaking head gasket (worst case scenario).

 

Agree that that is not normal. You probably have a slow leak somewhere. As mentioned, pressurize the system and look for a coolant leak, also inspect the coolant overflow bottle thoroughly.

 

Do I need a motorcycle specific pressure tester? I seem to recall a mechanic telling me it's not the same as one for a car.

Any recommendations?


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A test kit should have multiple connectors to fit any size opening....

 

Ok sounds good. How many pounds of pressure should I apply?


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From Manual.

 

Does the rad cap list it's max pressure. I remember reading a post a while back on VFRD that mentioned the pressure on the 3rd gen bikes as about 15 PSI. I wouldn't apply more pressure to the system than what the cap is designed for.

 

Coolant Conundrum

A 50/50 mix will boil at 226'F with no pressure.
At 15psi (about normal for most motors these days) it boils at 265'F (Honda Service Manual).

The Rad Cap has 2 valves in it, a big one for Over-Pressure to get out.
On cool down there is a small metal disc in the middle, on a wimpy spring, that lets the coolant back into the Rad when the engine cools.
Both valves have to work properly.
Typically, the small Return Valve gets Rusty, Gums up or will not seal, so it leaks, you don't get 15psi.
Now the coolant will boil at a lower temp. It gets pretty hot near the Exhaust Ports.
If it boils, you get bubbles, air at the top of the rad.
Air will expand way more than coolant and that will push Coolant out, through the Reservoir Overflow tube.
With less coolant in the system, you've lost some system heat capacity, the motor will run hotter,,.. its a RunAway.

Every time I take off a Rad Cap, I always thoroughly wash/clean it.
If in doubt, replace it.

You should replace the cheap coolant every 2 years.
The Long Life stuff should last 5 years.
Get the Long Life, it really is better stuff and it doesn't cost that much more.
Always mix with Distilled water, or the precipitates will clog things up

You could leave your bike sit for a year, and there should be NO coolant loss.
I've left my Gen1 sit or 5 years once (had some kids), and it never lost a drop.

Someone was saying that some Subaru/Izuzu rad caps are a close match and cheaper.
They probably run at the same pressure.

Good Luck