simmsy Posted December 28, 2009 Report Share Posted December 28, 2009 (edited) I can see various overheating solutions and a lot of good information posted, but I can not see anything that is related to my problem, so hear goes. I have just returned home after a 3 hour trail/Trial ride. Everything was going well until I had just completed a 10ft steep incline and as I reached the top there was an allmighty explosion of steam blowing off from my radiator cap. It is a real cold day and the fan has been coming in from time to time. the bike has ran well all day and am not sure where to start, I returned home from the ride and have since filled the radiator back up with water/anti-freeze mix. What do I need to check before my next ride? Any help will be appriciated. Thanks in advance Jeff Edited December 28, 2009 by simmsy Quote Link to comment Share on other sites More sharing options...
nzralphy Posted December 28, 2009 Report Share Posted December 28, 2009 I'd say that the cylinder head oring has blown and cylinder pressure is getting into the cooling system. I'd whip the head off it and check this....and replace the orings as a matter of course cos they go hard. Quote Link to comment Share on other sites More sharing options...
dan williams Posted December 28, 2009 Report Share Posted December 28, 2009 You need several thing for the system to function. A working water pump. A well sealed system to maintain adequate pressure to keep the water from boiling. A working fan and switch/electrical system. Enough fluid in the system to circulate effectively. Two possible scenarios, 1 Failure of the cooling system. 2 Over heating of the engine from something other then the cooling system. If the engine ran properly at the time of the failure, no pinging or loss of power it's unlikely to be #2. Just because the fan was coming on all day doesn't mean the fan or switch didn't just fail at the end of the day. I think this is the most likely explaination. I've never had a switch failure right at the start of the day. Always in the middle of an event when all of a sudden I'm getting steamed like broccoli. You know the test, just start it up and short out the switch to see if the fan runs. If it does then wait for the engine to heat up and see if the switch switches. If it does then you got a real mystery. I would hope it was just low coolant. Something I found in my truck last week. Engine was fine but heater was sporadic. Weird but cheap to fix. You can try running the engine briefly with a coolant hose disconnected to make sure the pump is working. Betas with magnesium cases have a reputation for corroding the water pump housing but it's much less common with aluminum cases like your '05. Might be worth pulling the side cover off for a peek. Don't get stressed over it. It's fairly common to have this happen at some point in your trials career and it's usually the switch gone bad. Quote Link to comment Share on other sites More sharing options...
stork955 Posted December 28, 2009 Report Share Posted December 28, 2009 Gday, further to the above, make sure the radiator itself is not blocked with mud etc and has free airflow through. If the fan works OK and the radiator is clear it is possible that the cap has failed and wont hold pressure. Very hard to test though. Make sure that the seals inside the cap (there will be 2) look OK. Do these checks before dismantling the engine. Cheers, Stork Quote Link to comment Share on other sites More sharing options...
simmsy Posted December 28, 2009 Author Report Share Posted December 28, 2009 You need several thing for the system to function. A working water pump. A well sealed system to maintain adequate pressure to keep the water from boiling. A working fan and switch/electrical system. Enough fluid in the system to circulate effectively. Two possible scenarios, 1 Failure of the cooling system. 2 Over heating of the engine from something other then the cooling system. If the engine ran properly at the time of the failure, no pinging or loss of power it's unlikely to be #2. Just because the fan was coming on all day doesn't mean the fan or switch didn't just fail at the end of the day. I think this is the most likely explaination. I've never had a switch failure right at the start of the day. Always in the middle of an event when all of a sudden I'm getting steamed like broccoli. You know the test, just start it up and short out the switch to see if the fan runs. If it does then wait for the engine to heat up and see if the switch switches. If it does then you got a real mystery. I would hope it was just low coolant. Something I found in my truck last week. Engine was fine but heater was sporadic. Weird but cheap to fix. You can try running the engine briefly with a coolant hose disconnected to make sure the pump is working. Betas with magnesium cases have a reputation for corroding the water pump housing but it's much less common with aluminum cases like your '05. Might be worth pulling the side cover off for a peek. Don't get stressed over it. It's fairly common to have this happen at some point in your trials career and it's usually the switch gone bad. Thanks for the quick replies. Can you tell me where I would find this switch and how to test if it is working. Thanks Quote Link to comment Share on other sites More sharing options...
simmsy Posted December 28, 2009 Author Report Share Posted December 28, 2009 Gday, further to the above, make sure the radiator itself is not blocked with mud etc and has free airflow through. If the fan works OK and the radiator is clear it is possible that the cap has failed and wont hold pressure. Very hard to test though. Make sure that the seals inside the cap (there will be 2) look OK. Do these checks before dismantling the engine. Cheers, Stork Thanks I will check these first. Quote Link to comment Share on other sites More sharing options...
dan williams Posted December 29, 2009 Report Share Posted December 29, 2009 (edited) Thanks for the quick replies.Can you tell me where I would find this switch and how to test if it is working. Thanks Yup, brass hexnut looking thingy with two wires coming out of it. On your bike I think it will be on the bottom right corner of the radiator. Most people will just stick a screwdriver across the two terminals. Fan should come on. Be careful though because it's not the most robust piece of gear and if you put pressure on the terminals they'll snap. As for actually testing the switch you can do what most people do and just run the bike until the fan comes on or go whole hog and throw an Ohm meter on it while dipping it in boiling water. Usually I find it just worth it to test it on the bike, and have a spare in the toolbox. Little beggars are pricey though. Edited December 29, 2009 by Dan Williams Quote Link to comment Share on other sites More sharing options...
shercoman2k8 Posted December 29, 2009 Report Share Posted December 29, 2009 Sorry to hijack your topic but I'm having a simillar problem with my sherco, cooling systems fine, fan cycles in and out as normal, bike doesnt overheat, no loss of power but occasionaly it'll spit out a few ml's of coolant, maybe every 15 minutes or so? Dodgy cap? I seem to beleive its not the o-rings, as it would be more constant? Quote Link to comment Share on other sites More sharing options...
dan williams Posted December 29, 2009 Report Share Posted December 29, 2009 Hi Shercoman. cooling systems are designed to run under some pressure. This keeps the coolant from boiling even above the temperature it would boil at in open air. That's why the temp guage in your car can show 230 degrees and the water's not spewing out everywhere. It's also why a pinhole screws up the whole system. The cap acts to regulate that pressure. Too much and the cap is supposed to vent if the system pressure gets too high. That's why the cap has a tube on it. Just like your car it's intended to dump into a reservoir but on trials bike they don't bother with the reservoir. It could be your cap is venting at too low a pressure but the cap could be fine and something else in the system is causing the pressure to spike. Check your cold fluid level and make sure you are using the proper coolant. I now use propylene glycol based like Engine Ice or Silkolene Pro-Cool. That way I don't feel bad for destroying the planet when I screw up working on the bike and pour half the cooling system on my shoes. Actually the real reason is it's premixed with distilled water which is critical on the newer bikes with magnesium cases. Tap water and bottled water will do only if necessary but they contain ionic contaminants which act as electrolytes turning your cooling system into one big electroplate tank. Unfortunately the magnesium cases become the sacrificial electrode. If you use tap water flush that stuff out ASAP. Ron Commo Sr. who is the big dog in the US on all things Beta used to tell me to not completely fill the cooling system and I was always having to put more fluid in. One day I decided to challenge the conventional wisdom and just fill it to the top. I haven't lost coolant yet. That alone defies logic as the expansion of hot fluid alone should displace some. Does your bike only do this under certain conditions like really hot weather (weakness in cooling system like a blocked radiator) or really cold weather (lean mixture because of denser air) or after a long slow climb (heats up all bikes)? Is your radiator clean? Gotta have air flow or the fan's just a party noise maker. Is your ignition advanced to give a little extra "snap". Are you running good fuel? Low octane fuel that causes minor pre-ignition will spike engine temperature. All in all it doesn't sound like too big of an issue. Quote Link to comment Share on other sites More sharing options...
shercoman2k8 Posted January 4, 2010 Report Share Posted January 4, 2010 Hi Shercoman. cooling systems are designed to run under some pressure. This keeps the coolant from boiling even above the temperature it would boil at in open air. That's why the temp guage in your car can show 230 degrees and the water's not spewing out everywhere. It's also why a pinhole screws up the whole system. The cap acts to regulate that pressure. Too much and the cap is supposed to vent if the system pressure gets too high. That's why the cap has a tube on it. Just like your car it's intended to dump into a reservoir but on trials bike they don't bother with the reservoir. It could be your cap is venting at too low a pressure but the cap could be fine and something else in the system is causing the pressure to spike. Check your cold fluid level and make sure you are using the proper coolant. I now use propylene glycol based like Engine Ice or Silkolene Pro-Cool. That way I don't feel bad for destroying the planet when I screw up working on the bike and pour half the cooling system on my shoes. Actually the real reason is it's premixed with distilled water which is critical on the newer bikes with magnesium cases. Tap water and bottled water will do only if necessary but they contain ionic contaminants which act as electrolytes turning your cooling system into one big electroplate tank. Unfortunately the magnesium cases become the sacrificial electrode. If you use tap water flush that stuff out ASAP. Ron Commo Sr. who is the big dog in the US on all things Beta used to tell me to not completely fill the cooling system and I was always having to put more fluid in. One day I decided to challenge the conventional wisdom and just fill it to the top. I haven't lost coolant yet. That alone defies logic as the expansion of hot fluid alone should displace some. Does your bike only do this under certain conditions like really hot weather (weakness in cooling system like a blocked radiator) or really cold weather (lean mixture because of denser air) or after a long slow climb (heats up all bikes)? Is your radiator clean? Gotta have air flow or the fan's just a party noise maker. Is your ignition advanced to give a little extra "snap". Are you running good fuel? Low octane fuel that causes minor pre-ignition will spike engine temperature. All in all it doesn't sound like too big of an issue. Very good post, thank you! I've only really noticed it recently, after replacing the crank seals... It ran fine for a week or so, but with an air lock developed in the pipe from the water pump. I cleared this and its ran fine since. Just recently though we've had a major cold snap, temperatures dropping to -20 Degrees Celcius at nights, and not going much higher than -5 in the daytime. Snow on the ground has stopped me taking it for a proper blast though. The coolant I use is rated to -30 degrees, and upto 270. Valvoline stuff I beleive, so it's not icing up in the pipes or anything. Using an 80:1 mix of 98 octane fuel. Advanced a bit I beleive, but never had problems before. It's a Paxau Sherco, if you were wondering or if it's of any help. Now, after running it today, I dont think I saw the fan come on once, within thirty minutes of it being on the paddock stand. Maybe before it was just intermittent and causing it to occasionaly overheat, and then kick in? It's lost A LOT of coolant though. Thinking about it actually, it only seems to be since i've fitted the titanium frontpipe? I keep thinking it could be running lean, but my exhaust is more full of gunk than ever, and even spraying carbon laced crap out the end of the muff! Could it just be the cold causing the oil to go all thick? Will take this to the sherco forum, and let Mr Manny here get his own thread back. I'll catch you over there as you seem to be a great help. Jamie Quote Link to comment Share on other sites More sharing options...
shercoman2k8 Posted January 6, 2010 Report Share Posted January 6, 2010 http://www.trialscentral.com/forums/index....showtopic=28561 Anyway, help this guy out now, sorry to steal your thread. Quote Link to comment Share on other sites More sharing options...
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