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Still overheating

Discussion in 'Technical and Troubleshooting Torque' started by Paulie, Mar 12, 2006.

  1. Hey all. The mighty GPX is still being a thorn in the crown. I posted a while back that she kept overheating and have since tried to fix it following alot of advice obtained here so here is a list of what i have done:

    1. Changed Radiator cap
    2. Changed thermostat
    3. Flushed radiator
    4. Refilled radiator
    5. Changed fan switch
    6. Changed Fan
    7. Taken it to bike shop who can't find anything wrong with it!

    yesterday I went for a ride to wisemans ferry and she overheated as I rolled into town.. she was ok when we were moving at speed but as soon as we stopped.. temperature went straight up to red. The new fan I replaced seems to be working intimitantly but I can't understand why, and even when it IS working it doesnt seem to bring the temperature down. On the way back from wisemans I had to lane split as soon as I got into castle hill because she was so close to redline so i had to split the whole way home..it was fun, but I just worry that I am doin harm to her.

    Anyone have any further thoughts? I'd appreciate it, thanks guys/gals

  2. Okay a few obvious questions - is the bike losing coolant and is there any evidence of water in the oil.
  3. No evidence of coolant in the oil or vice versa. The only time it uses coolant is when it goes into the red and it drips a little out of the overflow hose under the seat. But the coolant level remains pretty much full. Though, i did notice when I put the new fan on the other day that the radiator itself was only about half full but the radiator filler bottle thing under the seat was reading full?
  4. My guess then would be some sort of airlock in the coolant system, a common problem on mid-engined cars (due to the length of the coolant lines) but seems a little odd to have happen on a bike. Only other possibility I can think of would be some sort of blockage in the water jacket of the engine but I don't think it's possible to drain the coolant from the engine itself on a bike (or is it?).
  5. By the sounds of this you have what is know'n as an airlock in the cooling system, and needs to be 'bled' out. Is there a small bolt up high in the cooling system that dont seem to be there for any other reason other than 'its there'
    :LOL: if so that could be the air bleeder etc etc , if you need more detailed instructions on how to bleed the system out just ask.

    But basicaly its the same as bleeding the brake system, but with the eng
    OFF , remove the bleeder bolt remove the radiator cap and keep filling till you only get H2O coming out of the hole and then replace the bolt

    or as JD said above :)
  6. Yeh there may be an airlock in the system somewhere but you'd think the bike shop would find that?

    I wonder if some coolant passages in the engine could be blocked?

    Is the bike still making full power? Sometimes if a bikes is seizing the piston or a big end bearing, it'll run hot before it finally locks solid or makes a loud clanging noise.

    There are so many GPX's running around, and have been for years, there would be an inherent problem causing this that I'm sure a Kawa dealer would know straight off.
  7. You've got me jd. Why wouldn't it be possible. If you can get cooant in, you should be able to get it out.

    Paulie, did the whole system get cleaned when the radiator was flushed or did they only do halve the job (which often happens)? Also when you had this done, what codition was the collant in, nice and green or rusty water? If it was the later then I'd be betting on a block in the engine. I'd also not be ruling this out if it was green because it may have been quickly replaced just before it was sold. :)
  8. Coolant generally goes in at the radiator or overflow bottle. What I'm talking about are the drain plug(s) on the bottom of the engine block itself (usually found on car engines) that allow you to drain and flush the water jacket of the engine - not just the radiator. Haven't seen these though on bike engines, but then can't say I've really looked either (don't often spend time sitting under a bike :wink:).
  9. When I flushed trhe radiator it was pretty clean, wouldnt the airlock be gone by now though? Because the coolant has been replaced?

    I'll try that bleeding the radiator, sounds pretty easy.... Its just odd that the fan doesnt ALWAYS kick in? I mean, I replaced the thermostat, fan switch AND fan assembly....
  10. Disconect eveything and let gravity take over from there. I didn't say there was an easy way, but I can't believe it's not possible.
  11. The fan switch is normally on the top tank of the radiator and if that is in the middle of the 'airlock' it wont work properly were as the eng temp is taken from a sensor on the top of one of the heads
  12. its all so difficult, what should I do? try and find anotheer bike shop? Hmmm... what I might do is find another bike place, tell them what the problem is and make sure that they can look at it as soon as I bring it in while its hot? that way they may be able to see whats not workin or somethin>?
  13. You'll likely have a hard time finding a shop that'll commit to having a look at random. The other problem is you'll have to ride an overheated bike to the shop and risk serious damage.

    Find another shop and explain what happened and have them have a look. Explain what's already been done, what hasn't been done and that the previous shop couldn't locate the problem. This way you're giving them somewhaere to start the investigation without following dead leads. :)
  14. Follow VTRBobs advice for bleeding the air from the system and see if that solves the problem. If you're not confident in doing that yourself then try taking it to a bike shop and tell them you have an airlock. If they don't know what you're talking about go to another mechanic. The airlock is a problem, if the bike still overheats after eliminating that then you may also have crud blocking up the system.
  15. Search for a manual, most (all) will have how to flush, refill and bleed the cooling system.

    Also check the temp guage (and sender) is actually working OK.
    The manual should tell you the figures, but basically you drop the sender into an old pot of water with a multimeter hooked up and a thermometer in the pot with the water. Start boiling the water and read the resistance on the multimeter, it should match the specs. You could just be reading "normal" temp with a shonky guage/sender.

    Does it lose water/coolant? When you flushed out the block and radiator (separately I hope) was there good flow going through?

  16. I reckon you have a cracked head. (No not that one, one on the bike)

    I had a ford and it did exactly the same. I even tried to fix it the same way you have. I fitted a massive fan and air scoops and large water res. Nothing worked. Once it got hot that was it. As long as I kept going it was ok, but stop and all the water got dumped on the road under pressure.

    I found some stuff a local mech got given by a traveller (it had copper stuff in it from memory, it was about 12 yrs ago) I put in 2 bottles (because it was a 351) and it fixed it. I removed the big fan and air scoops, never needed them again.

    The compression test did not show any problem but it was pressurising the water system when it got hot.

    Once this stuff went into the oil and I ran it for about 100 k, it had to get hot and cold at least twice, the problem was gone.

    I would try that fix. If it is wrong, the only cost will be the stuff you put in.

    I can't remember what it was called but I am sure a mech could find out. It was not wynns or any of those off the shelf. All I can remember is that it was a 50ml bottle and it had copper in it. The idea was that when the crack opened it went in. When it cooled the pressure made it go solid. Next time it got hot the crack was smaller, and so on.

    Good luck.
  17. I'd be looking at bleeding the system first .. rather than just filling it with coolant and leaving it at that???

    Definately worth trying to bleed the system though .. on my Kwaka ZL1000 it has to be done with the motor hot/running. There's a bleeder bolt/nipple on the thermostat housing ..

    Here's a link to how to bleed the cooling system as posted on the Kwaka ZRX forum ... http://www.zrxoa.org/webpages/techinfo/cooling/BleedCoolingSystem.html

    The stuff with the copper in it is Cargo brand "Metallic Seal Up" ... available at Bursons, Autobarn or Repco etc ..

    This is the stuff to look for ... if you're going to go that route ..


    Bear in mind this is a "band-aid" remedy and whilst it may work .. it's a "patch-up repair" which is not addressing what may be the actual cause .. ie: a blown head gasket and/or a cracked head ..

    Hope this helps ...
  18. One other possibility is that your carbies might be delivering too lean a mixture (some of the jets may be clogged, or the mixture could just be out). This would produce a lot more heat... Cooling system sounds more likely, but this is something else to check if that fails.

  19. Mate, come to think of it, I never really had the heating problem (that I can remember) Until I got the carbies cleanned out! I found a mechanic guy to fix it cause I wasnt getting power (I posted that problem sometime last year) he told me that there was a wad of glue blocking one of the jets because someone dodgied up the carbie by using glue instead of replacing the O-ring when they rebuilt the carbies, he said he then cleanned them out and stuff, that fixed the power problem but yeah, maybe you,re right because I dont remember having this heating problem before that! hmmmm...