NC30: Fan Switches Off Other Bikes?

[MementoMori]

OK, bike's been off the road for a while as had no tax and had only recently got it back from the garage who MOT'd it.

So was giving it quite a thrashing to blow out the cobwebs when after about 15 minutes in the sticks, my right leg started to get hot (usually only does this round town, as most NC30 owners will be familiar with!). Looked down at my temp gauge to find the needle had gone past the red mark and into the H!

Prayed to the God of Honda and we got home without issue. After waiting for the bike to cool down, opened the radiator cap only to find that there was no coolant whatsoever in the system. Poured water in and checked that there were no leaks. Ran the bike with the cap off to ensure there would be no airlock. Put cap back on and ran bike again. Bike started to overheat once more.

Switched bike off for a while, then wanted to check the fan. Turned ignition on and fan started going ten to the dozen, so fan, thermostat and water pump all appear to be working. No leaks in the system and appears to be flowing through fine, although can't clarify this.

It is possible that the garage who MOT'd the bike did not replace the coolant, however we managed to get the bike back from the garage with no problems and the journey takes a good 20 minutes.

However, if this is not the case, what else could be causing the overheating? Will be draining the system and filling it with coolant tomorrow just to rule the above possibility out.

Does anyone have any ideas what may be the problem?

Thanks in advance.

EDIT: Changed title, new Q at bottom of page.
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The tiger who came for a pint

[MaybeGuy]

check what colour your oil is and get back to us
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Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!!
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[Robby]

Did you let it cool down fully before putting water in? If an engine has got hot enough to warp things, the sudden cooling effect of putting water in can be a bad thing.

As for where the water went, could be lots of places. If it got into your oil I would expect your oil level to be sky high, and a very funny colour.

Could be a pinprick hole in a pipe which is only letting the water out as steam when it gets hot enough - used to have a car that did this, a pipe bandage from halfords cured it.

Drain the system down, flush it with a hose, refill with coolant, and keep an eye on the level. Pray you haven't warped something.

Also if the coolant and oil are mixing, it isn't necessarily head gasket - My old SV650 had a break in the gasket separating the water pump from the crankcase, and it leaked through there.

[MementoMori]

Oil is normal colour and consistency.

Will drain and refill tomorrow and see how that goes.

Thanks so far. Hopefully it is just that.
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The tiger who came for a pint

[loply]

Btw mate the MOT test doesnt involve changing your coolant.

Only if you had agreed with them that you were getting a service (which involved coolant change) would they do this.
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Yamaha SZR660 Caution to the wind, the throttle pinned!

[MementoMori]

Yeah, they had given it a bit of a service aswell, not that they did anything useful.

But they would have had to remove the radiator at some point. Should have mentioned this in my OP, apologies.
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The tiger who came for a pint

[MementoMori]

BTW, didn't put cold water into the radiator when checking for leaks, the water was straight from the kettle so was hot.
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The tiger who came for a pint

[MementoMori]

OK, drained and refilled the system. Was still overheating when noticed the fan wasn't working. Tested the electrics, they were fine, tested the fan by itself by hooking it up to a battery and it worked great so currently being led to believe it's the fan switch.

Gonna take the tank off in a bit just to be positive it's not a pinched wiring loom or anything but I reckon it is the fan switch.

If there are any other possibilities, could anyone let me know please as would like to rule everything out before buying stuff I don't need.

Cheers.
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The tiger who came for a pint

[Finglonga]

Probably worth putting a fan switch in if you cant find anything obvious, start with the cheap stuff first.
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Andy Sez....
F.Y.Y.F.F.

[Irezumi aka Reuben]

Does anyone know if any fan switches from other models of Honda's or makes of bike will fit onto MementoMori's VFR400 that may be cheaper than the RRP that Honda charge for the VFR400 one?
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Pictorgraphicalfantastical

[bish777]

try it with the fan switch, but if it persists completely remove the thermostat and try again. Overboiling is usually the sign of a dying thermostat. That killed my FZR1000.
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GSXR1100J