spitting out coolant and getting hot?

[zxrkat]

Hi guys,virtually same question i asked ages ago but i have still got probs, my vfr400 nc30 is still getting hot,i have renewed thermostat and have now done away with it, have just done a double header at cadwell and it was brillaint apart from the temp gauge is all over the place and it spat coolant out,not sure from where tho.temp will fluctuate over session.There doesnt seem to be water in the overspill bottle either, have just stripped whole coolant system and apart from hoses being a bit old i cant find owt wrong yet??? Any ideas please

[Old Painless]

If the temp gauge is having a fit it may be the electrical connection to the rad and/or thermostat housing ?

[CMSMJ1]

knackered rad cap is what I reckon.

Where you at? Have you got a spare? They are a fairly common fitment...


Reading it again why don't you know where the collant is coming from?

Get it on stands and fairings off and warm it up - you need to see if it is out the cap, the over flow, a hose or what? If there is a lack of pressure in the system due to a leak then it will overheat easier anyway so you have a double whammy.

Do you use the standard coolant overflow bottle? Does it full up at all when getting hot? If not, is the hose that leads from the rad to the bottle have any leaks or is it crimped?

If the bike cannot overflow then you will have too much pressure and any old hoses or loose clamps will maybe leak..

This should be an easy fix...it is a simple part of the bike and so you should be able to figure outn where it is failing and sort it on worries.

[zxrkat]

Will check connection on thermo for bad wiring, just dont understand why its still spitting water,it will run fine for about 3 sessions or half hour on road then temp builds up, just hope waterways inside not blocking up.

[zxrkat]

cant where its leaking from cos it does it while moving,mate sed he could see it coming out from track side,but wen i got back its over fairings left side of bike, have stripped everything off now and some hoses are bad, no obvious bits tho?? Based down in southampton.

[Martin]

My best bet is it's the waterpump if you can't see where it's coming from. Inside the pump there's an o-ring which isn't replaceable. If this seal goes, in order to stop coolant filling the engine, there is a little drain hole on the underside of the pump where the coolant will escape. Get the bike up to temp, have someone rev the bike and see if any coolant escapes from there. The higher the revs the more coolant will be pumped out, at idle you'll be pushed to notice anything. The only fix if it is this is another pump

[zxrkat]

Thanks will try that,seems to be an annoying glitch on what is a great bike!!

[Neosophist]

Cooling system is quite simple when you know how it works so fixing it shouldn't be a problem!

Drain the rad and remove the thermostat for this one (if you havn't already)

Undo the lower hose by the water pump and Get a hose pipe and flush loads of clean water through the radiator fill hole, it'll all come out the bottom, then put the hose in the water pump and flush it through the rest of the engine.. will come out bottom of rad / radiaotr fill hole.

Once youve flushed out the engine as best as possible

Remvoe the waterpump cover.. not the pump itself as you'll get oil everywhere.

Check the fins are all there and crank the throttle.. it should spin ok!

Check the drainhole on the understide of the waterpump.. if it's loeaking from here the waterpump is knackered and you need a new one.

The rad-cap should seal propley.. you can have it pressure tested, a new one is £18.00 ish.. they need to hold pressure otherwise the coolant will boil too early (coolant under pressure boils at a higher temp)

If it isn't holding pressure it'll be just throwing it into the expansion tank.

Holts do a 2 part chemical coolant system clean.. get this NOT the sand stuff if you want to clean it.. you refil your coolant system with this and water and heat it up for half hour.. leave it then drain.. will make the insides spotless!

Then finally flush again and fill up with distilled water and silica free (motorcycle safe) antifreeze 50/50.

Bleed it by starting the bike up on the side stand and let it get upto temp (half way) then snap the throttle to 5000rpm and let it settle.. do this 3 or 4 times to purge any air.

Turn it off and let it cool.. refill the rad up as the air comming out causes the level to drop.. replace the cap and your good to go.