NC30 mystery: the case of the dissapearing coolant....

[Smoky]

right- am quite stumped by this one, maybe ive missed something, or im not looking in the right place.. here the problem:
checked the coolant level last week, noticed it was wuite low, so topped it up, and all was well.
checked it again this weekend and... nothing.
empty bottle. like bone dry.
so, worried it might be escaping into my crankcase somehow, i popped into my local garage.
after running a coolant system pressure check he informed me that its not a head gasket, and he couldnt find any significant leaks in the system... checked the oil level, and oil condition-
ive kept an eye on it myself, and it doesnt appear to be throwing coolant out everywhere... im pretty sure i would have noticed that.
so the question is... where is it going?

oh, and he also advised me to remove the thermostat- since my rads arent in great condition and she tends to get quite hot...
any help on this would be greatly appreciated as always...
Smoky-

[CMSMJ1]

Are you looking in the rads or in the overflow bottle?

Also - removing the thermostat is poor advice from a mechanic. Why not cure the problem rather than try to mask it. If the rads don't work then they don't work. Get them cleaned!

I know as mine are made of muddy flie carcasses and my bike was running into the red yesterday and was not cooling below 90 even going at 90!

If the level is low in the oveflow - then fill it up. If it boils over it comes out of the bottle and pees on the floor..so when it cools down that water is lost. no big deal...just fill it up

[Smoky]

If it boils over it comes out of the bottle and pees on the floor

i dont have an overflow bottle.. guess i should invest in one lol.
i was looking in the coolant tank- theres was fluid in the rads, (i checked) but the tank was dry....
as for the rads, ive got a 2nd hand set on the way to be re-cored any day now, i must admit the bike did run cooler without the thermostat, but i fully intend on re-fitting it when the summer starts to fade.

so i shouldnt be too worried about the loss of coolant? even if i find the tank completely dry?

[CMSMJ1]

The overflo - under and the coolant bottle are the same thing. Under the right hand seat?

Just get it filled up - it should have min/max lines, fill it to that, make sure the rads are full and then whenever you get too hot the tank will fill...and if too hot it will pee on the floor. When it cools again the rads suck the coolant out of the tank. So as long as you keep some fluid in it you'll be right

[Smoky]

ga-roovy.
cheers buddy, will just have to keep a close eye on it and keep her topped up.
thanks mate, much appreciated
Smoky-

[The Hamster]

For a definitive test, just take all the fairings off around the engine, start it up and let it fast idle, around 2000rpm until the tmeperature gauge is reading quite high, maybe 100+. Then check for leaks whilst it is running. By the sounds of it, you may have a leak in one of the pipes or connections that is only present at high temperatures and pressures when the pipes are getting flimsy.

If your running it at 100 degrees, and you cant visually notice any leak, and youve obviously had the engine pressure tested and checked the oil for water etc, then i cant possibly see where else any water would be going??

[Neosophist]

Ok.. firstly.

Expansion Bottle: Bottle containing about 300ml of coolant, when the radiator is upto temp this holds any excess fluid thats expanded from the radiator.

Overflow: Pipe that allows coolant to drip on the floor. This comes off your expansion bottle (i think anyway)

There are a few reasons you could be loosing water. Listed in most 'phantom order'

1. The metal pipe that runs across the V is leaking somehow. I had one that had a hairline fracture in it, when the bike was upto temp it was spraying a fine mist of steam/water out but it drained to coolant fairly quickley and was a complete twat to track down.

-With the bike upto temp look in the V, you'll need the side panels off, theres a Metal pipe thats sealed with an O-ring each side that carries coolant across the engine. Check for leaks here.

2. You radiator caps knackered and letting too much water out into the expansion bottle and overflowing (you'd see the water trail i guess) or it could be leaking just enough to let water seep out.

-Check the rubber is sealing propely and doesn't look old and perished. You can have it 'pressure tested' to make sure its upto speck 1.1bar..

3. You have a crack in one of the cylinders that letting water into the combustion chamber.

-You'll notice this by continious steaming from the exhaust even after the bike is warmed up.

4. A hose or pipe is failing at higher temperature / increased pressure.

-Quite common with older hoses, check for loose jubilee clamps and drips around pipes when bike is warm.

5. Good old HGF, quite unusal on the VFR's as the headgaskets are tough... I rode an NC35 150 miles with no water pump and it didn't overheat if i kept it below 60.. i'm guessing convection cooling? either way.. there usually tough as nails..

-Check your oil for creaminess,


The suggestion of idling the bike upto temp is a good idea. cover the area with newspaper so any drips will show up easier

[Smoky]

The metal pipe that runs across the V is leaking somehow. I had one that had a hairline fracture in it, when the bike was upto temp it was spraying a fine mist of steam/water out but it drained to coolant fairly quickley and was a complete twat to track down.

thats a good point... ill have to have a look at that...

3. You have a crack in one of the cylinders that letting water into the combustion chamber.

-You'll notice this by continious steaming from the exhaust even after the bike is warmed up

dont think its that, no excess smoke at all...

4. A hose or pipe is failing at higher temperature / increased pressure.

-Quite common with older hoses, check for loose jubilee clamps and drips around pipes when bike is warm.

could be, ill give it a good going over when i next get the chance....

5. Good old HGF, quite unusal on the VFR's as the headgaskets are tough... I rode an NC35 150 miles with no water pump and it didn't overheat if i kept it below 60.. i'm guessing convection cooling? either way.. there usually tough as nails..

-Check your oil for creaminess,

i had the system pressure checked, so i doubt it my head gaskets... checked the oil level and condition- no problem there...

hmmm i guess ill have to keep a close eye on it- see if itll give me any clues...

thanks for all the help so far guys!
Smoky