| Author | Message | ||
     Jdugger |
I'm stumped -- let's see if anyone has any ideas here. My teaching bike won't keep water in the cooling system. When the bike is ridden hard and gets hot, it spits water into the overflow, even if the system is very carefully bled and capped at near operating temps. So, of course, after a couple of cycles there's air in the system and it starts overheating and spitting out even MORE water until the bike just won't stay cool at all. I've seen this when a radiator cap gets old and doesn't hold pressure correctly, so I replaced that. But, it still does it. A buddy suggested the head gasket, but a leakdown confirmed the bike was holding compression. The oil is perfect -- no water getting in there. I've also run the bike up to VERY high temps (240F) at idle, and then shut it off to listen carefully for leaks. There's no fan on this bike, so that's easy to do. I can hear the rad cap gurgle a bit, but not water makes the overflow bottle! It only spits up when I go romp on the bike. Thoughts? | ||
| Cataract2 |
You mentioned there is no fan on the bike. From what I can tell the sideways rads aren't the most efficient at getting rid of heat. Since the system is designed to run the fans continuously once they turn on I'm betting the issue is your bike is getting quite hot while ridden hard and of course the coolant will do it's thing and go into the overflow. Maybe put the fans back on? Other idea is the overflow line from the rad is possibly bad and allowing air to seep in. | ||
| Jdugger |
I'm using the flexi-glass bodywork, so once moving, the bike stays plenty cool provided it's not burping water! I have the same set up on the race bike. Works just fine, and that bike has a lot more power and makes more heat. This is definitely a technical problem in the cooling system. It's possible a hose is leaking. That's why I ran the bike up so hot at idle and went looking for leaks. Didn't find any... ARGH! | ||
| Nuts4mc |
1) hoses and clamps...the clamps aren't the "top of the line"... the "corbin" style spring clamp looses temper and clamping strength when subjected to heat cycles...might want to replace them with screw type clamps. 2) check the small cross over hose...mine leaked only when hot..it was split at the end. 3) WASG (kinda like Cat2 said)....your post said you pressure checked the engine...but have you Pressure Tested the overflow tank? 4) out here in the extreme SWest...I run straight water (distilled) with Justice Brothers radiator additive...worked well to keep the temps "consistent" during rides. http://www.justicebrothers.com/products_carcare_ra diator_additives.htm here's a test article: http://www.turbomagazine.com/features/0703_turp_co oling_system_additives/ ...a hot turbo-engine breaks down the oil and seizes the turbo's shaft=not good 5...on the lighter side... the heat generated by your "spring-less" brake caliper is sending thermal waves right up into the right radiator causing the overheat issue! hope this helps | ||
| Jdugger |
Funny you mention those spring clamps... and you are right. I found one that leaked already! I'll go reclamp EVERYTHING and get rid of the OEM clamps, too. Why would it only do this at high RPM? | ||
| Kruizen |
Water pump is engine driven isn't it? Does pump speed change with engine speed? WAG totally | ||
| Nuts4mc |
Kruiz is correct... to "bleed" my system ( or any system I usually work on) I fill the radiators about 1/2 full (1.5 qts for the 1125)(please don't start the engine "empty" and THEN add coolant you risk the chance of wiping out a pump seal);start the engine and then add a little coolant till it's at the top of the neck ( keep the engine running)...when the thermostat opens there is a drop in coolant level and the air makes it's way out - add coolant to top off the system...if you rev the engine (not smart) and have the cap off - you get a face full of coolant...the pump is doing it's job. | ||
| Jdugger |
I bleed the same way. I will also add that I do a couple of heat cycles and a couple of start/stops each cycle. Air will come out when you start and especially stop the bike once above thermostat temps. Burp until when you kill the motor there's no level change and then run it to 190 and cap it hot. If you let it cool and top it off, that's OK, too, but you will get an initial overflow once the bike comes to temp. | ||
| Stimbrell |
Head gasket failure may be difficult to detect with a leak down test at first, becomes easier as the gasket failure becomes worse but I suspect your buddy may be correct. | ||
| Dhays1775 |
I'm just making an assumption here, but it might be because of the pressure/vaccum from the water pump. A leaking clamp could be sucking air in and causing your issues. Either way, best of luck!!! | ||
| Blake |
Engine running hot, lean? | ||
| Rodrob |
Check that the metal coolant hose across the front has not twisted and come in contact, or very close to the front header. The Flexiglas bodywork can make this happen as it did to mine. | ||
| Jdugger |
Update: I've still not been able to isolate this issue. If the bike is run below 6,000 RPM, no matter how hot it gets (took it to 240) it will not overflow. But, even in the 180F range it will easily start to overflow when ridden properly at high RPMs. Got a pressure diagnostic kit thing. I hope to manually pump the system to operating pressures and see if I can find a leak. Looking more and more like a head gasket. | ||
| Jimustanguitar |
Are you sure that the cap itself is good? I had one once (on a car) that would purge coolant into the overflow, but when the engine cooled it would just suck air back. Same results, water jacket eventually fills up with air and you overheat. It's much less common to have a bad cap on a bike, but it's worth the $5 to be sure. | ||
| Jdugger |
It's a new cap. A cheap auto zone cap yes but a new one. I've thought about trying to find a 1.3 bar cap instead of a 1.1 but I'm concerned about the higher pressures. I know this is an ordinary change on some other bikes used for racing. The Hesitation I have about that solution is I've never needed it before on my other machines | ||
| Sir_wadsalot |
It could be the cap, you could have a pin hole in a hose screwing up the pressure, or it could be a bad thermostat. If you're running water wetter, a pin hole won't drip, just evaporate out under pressure. If the thermostat's sticking, it flows at idle, but when you're flogging it the water's not moving correctly. Might be worth trying another cheap radiator cap too, they have been known to be bad from the store. Sounds like you've tried everything but the thermostat. | ||
| Jdugger |
Yea, haven't tried the thermostat yet but can confirm the 'stat at least appears to be open because when bleeding the system it's swirling around quite well. |
