Boiling RVF

[maciekmaciek19]

Guys,
My bike was overheating for the past few days. There were clouds of steam coming out of the water bottle.
Tonight I discovered that one of the hoses wasn't fitted properly and the rad got empty.
I fixed this and re-filled the system.
Started the bike with the rad open (to let the air out) and after 5 minuted the water got on boil...
Made sure the system is full (squeezed the hoses etc) closed the rad and left the engine going.
Now the steam is coming from under the top rad cap, the fan isn't coming on and the temp gauge is half way to the red line (probably incorrect reading).
Also the back water bottle is making crackling noise but the water in there isn't too hot.
I'm confused because the water is obviously boiling, temp gauge doesn't seem to reflect that and the fan isn't coming on...
Does this make any sense?
Also how to best test if the fan is operational? There is only one cable connected to a single pin on the thermo-switch in the lower radiator. Normally I would just short the fan cables to see if it works but here there is only one.
I won't be riding tomorrow so I hope you can give me some ideas I could apply tomorrow and get the bike ready!
Thanks All.

[fastdruid]

Disconnect the lead on the left side of the lower radiator and earth it while the ign is on. That'll test if the fan itself works.

Druid

[wullvfr]

if you remove the connector from the thermo switch and earth it the fan should come on...............

check the fuse just in case it has blown!!!!

as for the problem with the cooling system,is the engine actually overheating?is the gauge faulty?

first test i would do is test the fan,and make sure it does work!!!
is there definately enough water in the system......when the pressure builds up and the water expands through heat it should flow into the coolant reservoir/expansion tank at the rear of the bike...........

your radiator cap may be fooked......

the coolant system is pressurised which usually means boiling point is actually raised to around 110 degress c....

is the thermostat working,it is closed up until a certain temp so the engine heats up quicker and then opens to allow the coolant to flow through the radiators to cool it down thus trying to keep the engine at a steady temperature.


it is a strange one this.............


william

[CMSMJ1]

your radiator cap may be fooked......

That is where my money is - no pressure in the system allowing the water to escape hence the boiling dry and steam.

try a new cap if you can - Geoff33 on here will do you one for a bargain 2nd hand.

[Neosophist]

I'm going to presume the bike worked ok before you changed the coolant?

If so the radiator cap might have had it, have a look at the rubber seal under the cap, you can usually but not always see signs of cracked rubber when there on the way out, without a pressure tester you have no way of knowing for sure, if it hadn't been disturbed for a while though it is likely that this is the problem.

I still think you have either AIR in the system or some problem with the water pump, or possibly both.

Water boils at around 100 degrees when not under pressure, maybe even slightly higher when mixed with ethlyene glycol (anti-freeze) so even if your cap isn't holding water pressure, for the water to be boiling and producing steam it will need to be at least 100 degrees, which should make the temp gauge move towards the red i'd have thought.

While your having problems it might be best to check the system over thoroughly.

Remove the Rad lower hose and using a hosepipe flush water from the rad filler out the bottom hose, then the other way around, to help dislodge any crud.

Remove the waterpump cover and with the kill switch on crank the engine and make sure it turns around.. do not remove the water pump else all of the engine oil will come out with it.

Remove the thermostat and flush water through the engine block both ways too, there are drain screws underneath the front cylinder heads to help remove water.

Refit everything and make sure all the hose clamps and covers are seated correctly and tight.

Check the fuse to the fan is ok, turn the ignition to the on position and remove the wire from the fan switch on the radiator and touch it to the bodyworks earth and the fan should operate.

Do the same with the temperature sender (located on the thermostat housing) when earthed the temp gauge should goto the hottest mark.

To test the thermostat drop it in a pan of boiling water and it should open at least 8mm.

With the bike on the sidestand refill the system with coolant, give the lower pipes a gentle squeeze and restart the engine with the cap still off, after around 5 mins the bike should be warmed up and the water flowing with the thermostat open, snap the throttle a few times to around 5000rpm and watch the water surge, it should purge out any air-bubbles with it, turn off the engine, allow the bike to cool and top up the radiator if necesary.

make sure the expansion bottle is filled up to the max mark with coolant too and replace the rad cap.

If you now have problems the rad cap if likely to be letting water out too early so this needs to be replaced, ideally with a new one (about £18.00+vat from dave silvers)

You should have no more problems, the only device we have not tested is the fan switch, that turns the fan on, this is still quite easy to test but requires the right tools, I use a thermometer on the brass of the switch to note the temp, the book states 95-105 cut in, mine comes on at 94 so it's ok.

If everything else is working ok, a primative way to test is after you've earthed the wire (so you know the fan actually works) and when your cooling system is functioning leave the bike idling, the fan should be on when the needle is nearing the red mark.

Hope thats of some help

[maciekmaciek19]

Hi,
Many thanks for your comprehensive comments!
I must say I am a member of different boards (re different bikes) but this is the most helpful source! Thanks for this.
As for my problem I have found more than one potential cause.
One of the hoses was loose and the water was simply leaking out - this has been fixed, water refilled bike warmed, hoses squeezed etc.
My further observations indicate the the temp gauge is most likely stuffed, the temp switch is probably gone too. The fan is in working condition however will not go on.
The water boiled again yesterday.
I have ordered the thermo-switch. Planning to check the water pump later on this week.
As for the air in the system I don't know how to better bleed it... I've done as per Neosophist's advice.
My hope is that the fan switch will sort this out.
Do you guys know if it's easy to replace the temp sensor/gauge ?
Cheerio!

[fastdruid]

Check the water pump.

ISTR someone with very similar symptoms and his water pump had died.

Druid

[maciekmaciek19]

OK will do. On the weekend hopefully.
So the deal is when the pump dies the water doesn't circulate, just sits there and waits for some boiling time...?
I hope this is something I can fix myself. This bike is driving me crazy. I love it but it's bottomed out my pocket pretty badly...
Thanks guys!

[maciekmaciek19]

Hi,
Should the fan be going with ignition on, engin off but already really hot?
My fan doesn't but I think it should, should it?
Thanks!

[RVF007]

the fan works off the ignition and only once its reached the hot set point