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boiling coolant?

Discussion in 'Bling and Appearance' at netrider.net.au started by wheeler84, Oct 27, 2007.

  1. just took the cibby out for a 40k ride, the weather was hot as hell (~32C, no breeze and humid) and I spent nearly all my time stuck in traffic, and booting it at every opportunity. Was keeping an eye on the temp gauge and at worst in standstill traffic with exhaust pouring in my face, it only got slightly above normal.

    When I got back just before and switched her off, I could hear a gurgling noise that i've never noticed before - I dare say its never been there before.

    I started poking around and found that there was nothing leaking anywhere... then my suspicion turned to the coolant container and when I touched the lid it was pretty damn hot and I could feel the gurgling vibration coming through, so im pretty sure the coolant was boiling.

    The bike is at 29,940 km and I was planning to get a service once it hits 30k, but I planned on going on 1 more big ride beforehand tomorrow, about a 100k round trip at slow pace (mrs on pillion).

    Is it safe to assume that the coolant is either dirty/running low and that a easy ride in the cooler mountain air shouldn't be a problem? I'm gunna go out on a whim and speculate its not meant to happen.
  2. that gurgling sound is called cavitation and it and good . basically you have a trapped air pocket thats super heating (over boiling point) and can cause all sorts. i suggest let it completly cool down and top it up with coolant, the BLEED THE SYSTEM of any air.. I havnt ever worked on a cibby but its the same problem seen across any liquid cooled engines with low radiators
  3. OK, here's "Sealed Cooling Systems 101".

    As the water in the radiator of a hot engine gets towards boiling point, it blows past the pressure cap and down a hose to the coolant bottle you found. That noise was the hot water gurgling into the bottle. Do not open the bottle when the bike is hot, because surprise, surprise, as the engine cools down, there is a vacuum created in the radiator and the water is sucked back into it. Despite what you may think, just AFTER you turn the engine off, the water temperature actually RISES, because no air is coming through the radiator.

    Check the level of coolant in the tank when the bike is level and the engine is dead cold. If necessary top up to the 'fill line', and make sure if you have to put a reasonable amount in, that you add some approved coolant fluid, in the correct proportion.

    And, finally, when you are riding in the heat, watch the guage AND listen for the thermo fan to kick in. If it doesn't, get it checked and fixed, or you'll cook your motor (especially in Queensland!).
  4. damn that doesn't sound too good... for one I don't have any bike coolant handy, and two, I have no idea how to bleed the coolant system. Sounds like a job best left to a pro... the question is, is easy riding likely to cause problems for another 120km or so?
  5. Wheeler, read the post above :wink:.
  6. thanks paul didn't see your post until just now... the bike still has some cooling to do so i'll have to hold off till later this arvo to check the level...

    I take it you are suggesting to put plain water in for now until the service, would it need to be distilled water? I guess it doesn't really matter for 120km.

    provided the thermo gauge is accurate things are looking pretty good for the cooling system, it's never gone over 60%, although I haven't been through a summer yet.
  7. If when you measure it the level IS a bit low, then plain water will do for the moment, but the coolant DOES raise the boiling temperature and thus make the system more efficient.
  8. i took my cibby out on sunday and it was a hot dat but my bike sitting on 4/5 on the temp guage. admitably i was sitting on 150 a bit and went up mount gloruois (qld). can any1 recomend the best radiator fluid (highest boiling point).......... and yes i know its a 250 and they might not be up to that punishment.......... but their were 2 other 250's and they didnt have the same problem
  9. Read ur usr mnl & dat shld tell u evrythg u nd 2 kno.
  10. Although similar to boiling liquid, cavitation is very different an so are its causes.

    To my knowledge the only time you may see cavitation in an engine is in a diesel, due to vibrating cylinder walls that cause high/low pressure variances in the coolant.
    Cavitation is an effect due to pressure (low) not temperature.
  11. not yruin to hijack the thred, but i dont haved a manual...... i just want to know what its the best coolent to keep my bike off the H on the gauge
  12. it's a very common problem for cbr250's to over heat in the hot weather i hear :D, mine loves doing it, I've found installing a fan switch helps alot, turn it on when your sitting in traffic, instead of waiting for the bike to overheat, i installed one last week works very well.


  13. well, had the 30K service done, all the normal stuff was done and I let them know about the coolant situation.

    Strangely there is no mention of coolant on the invoice, so i'm wondering if it's standard to replace coolant every service? I hope they didn't top it up as I had tap water in there for a few k's...

    The bike is now running better than when I got it, new chain and sprockets make a huge difference to the smoothness of it all.

    Just went for a spirited ride and the temp was the same as before the service, while moving was say 40%, when stuck in traffic no worse that 60% of the way through the gauge. And yet when I got home and put my head near the coolant reservoir, I can hear the liquid boiling away.

    Perhaps the only difference is its not as loud as it was before. Which leads me to believe that its always been boiling, I just haven't got close enough to notice... do other bikes do the same after a decent ride - you can hear the coolant bubbling/splashing around if u get close to it just after u switch the bike off?
  14. 400k's after the service, I can still hear the coolant every time I switch the bike off. Today I had a nice surprise to switch off and witness coolant leaking from... somewhere... presumably from the reservoir although it didn't appear to be coming from the cap area - maybe theres an outlet somewhere hidden?

    Got on the phone to the mechanics, apparently they don't change coolant as part of a standard service, even though I specifically mentioned there was a problem with it.

    They said that they topped it up for me rather than replacing the fluid. Judging by the colour of the coolant that leaked, it definitely was crappy looking, very brown in colour. I suppose a mixture of very old coolant, tap water and a bit of new coolant.

    So looks like its back to the shop. I have to get a new back tire and have the new chain tightened so I won't be expecting any extra charges for the coolant situation unless something is actually faulty.

    Not the type of experience I was hoping for - they should've done better than that given my instructions.
  15. its not boiling mate, its doing exactly what it is meant to do!
  16. umm overflowing?

    BTW I haven't touched the coolant level since it was in the shop so you would have to assume they got the level right... I can't bloody see the level in my underground carpark, once i'm riding and its warm theres no use checking right...