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Coolant and steam blowout?

Discussion in 'Technical and Troubleshooting Torque' started by tom27, May 3, 2012.

  1. Hey guys,
    Today i just pulled into work on my 1997 honda cbr250r and after it being parked for 5 minutes or so, it blew out a cloud of steam and dumped a ****load of coolant on the floor. When i pulled up the temp wasn't that high... maybe hovering between 1/2 to 3/4 up the gauge and the bikes performance was fine while i was riding it. I never saw any coolant leaks before and i can't see it leaking after it dumped it all.
    My friend and i have been looking under the fairings and around the engine to try and see where it has come from but we can't find where it could have come from.
    I bought the bike maybe two days ago and it passed roadworthy and everything, i knew the guy who sold it to be and had seen him running it fine before. I haven't had time to check the coolant levels yet, but i assumed since he still rode it regularly, he kept it topped up. I haven't even ridden it that much since i have bought it.

    Does any know where it could have come from and what could have caused this?]

  2. Radiator Cap?
    Not sure of they have a vented system but I'd check and/or change the radiator cap and possibly get the system pressure tested.
  3. +1. Take the cap off, if there's any crystallised gunk around the seal give it a clean. If the system can't pressurise, it'll dump a load of coolant from the overflow. That's the common cause anyway. Good luck!
  4. Thanks for your quick replies :)
    since i haven't had a honda before i'm not 100% sure where the actual radiotor cap is, i've looked around it and the radiator but can't seem to find it
    what i did find though is that the coolant must have pressurized and then blown one of the hoses off and dumped it onto the exhaust, causing all the steam
    could that have been the issue?
  5. or is there supposed to be 2 hoses poking out next to the exhaust? i thought there was only one :S
    we have tried adding in a little more coolant to the resovoir and coolant comes straight out of it
  6. On my gixxer, there's two hoses, one is an overflow from the fuel tank, the other is from the cooling system.

    Does the coolant only come out when the engine is running? I'm no expert at all, but like I say, if it's dumping coolant, then you're system isn't pressurising. Or you could have a hose off of course. The rad cap should be on the top of the radiator.
  7. Nah, when the bike is off and try pouring coolant into the resovoire it's just coming straight out of one of the two hoses
    yeah i thought it should be on top too, but from where i can see, i can't find it, i might take a closer look
  8. Ok, I can only speak from experience. With a cool engine, it would only dump coolant once it was started and got up to about 60c. I would start with the rad cap then follow round the entire system looking for somewhere air could be getting in. You might have to lift the tank up. Once you correct the issue, you might have to bleed the system.

    Hopefully someone else with more knowledge will appear here soon :)
  9. Sounds like you've split a hose or a clamp has come loose, for it to leak when cold.

    Take your fairing off so you can have a good look around, fill the overflow bottle and watch for a leak. If it's gotten hot, you may have a sticky thermostat.
  10. Thanks cazzo
    I know where the leak is from, it's coming straight out of one of the hoses coming out from just above the exhaust. I thought only one of them was supposed to be a dump hose but there are two. When i try to fill the resovoir the coolant just comes straight out of one, could this one have popped off from too much pressure and then spat it out all over the place, including on the exhaust which caused the steam
  11. If there is two hoses, one should connect to the radiator somewhere around the neck where the cap is and the other run open to under the bike as an over flow.
    Follow both hoses to find if at least one is connected. Get back to us, pic would be good too.
  12. Hi

    Like on my CB1300, the radiator cap will be under the tank somewhere. Does the image below help track which hoses connect where?

  13. Wow you guys are awesome, first thing tomorrow i'll take a closer look in the light and take some photos! :)
  14. Thank you all so much for your input, i pulled it apart today and found the culprit. The radiator cap was screwed beyond repair. The rubber seal was hard, cracked and came off the cap... and when flushing the coolant, found a leak which came from a hose that had burst!
    So my guess is....Rad cap wasn't sealing, air getting into the cooling then the coolant boiling and then burst a hose?
  15. Could be. Sounds like you're close to curing the problem. Well done. It's good practice to change the coolant every year, using a good quality mix, as it eventually goes off and you have all that alloy in the engine to protect.
  16. I guess the guy just hadn't really looked into the radiator in a while, the seal seemed like it was pretty old, lol. I went got straight to a shop and found a new cap that went straight on, but since it's a grey import cbr250r i couldn't get the hose straight off the shelf, had to order it from gold coast team moto and won't have it in until wednesday =/
    It was a relief to know where the pop, steam, and coolant all came out from though. All in all, $15 for the cap and $15 for the hose so i'm fairly happy :)
    just can't ride until wednesday now :(
  17. Well done. You saved money and you know more about your bike too.
  18. Always worth a bit of an obstacle for a little more knowledge i'd say, eh? :D
  19. Just to be sure, when you say you got a new radiator cap, you got one that releases at the same nominated pressure, not just fits the hole, right?
  20. It should do yeah, i haven't been able to properly go about burping and pressure testing since i have to wait for the hose to come in :(
    But it's the one designed for mine and is identical to the old cap too
    but i guess i'll find that out once i get everything back together