View Full Version : Honda VFR800 Over Heating

27-07-10, 10:51 PM
Ok so here goes.
I have had the old girl for a while now and she has over heated a few times now, it is mainly when doing town riding or slow riding, when I was in Lyon France it completly lost all of its coolant, and I have had it a few times over here when it has pee'd all over the floor too.

Now when I had to fit the new exhaust system I had a clean out of the Rads, and pipes, made sure we had no blockage and that the overflow tank was A ok, checked the Rad cap was sealing and looking good, yet on Sat when it was warm and I was doing a fair bit of slow town ridding it wee'd on the floor again.

Does anybody have any ideas of what I could look for please??
Oh by the way the Fans do kick in at 104c when they are meant too but they dont cool it down enough by the looks of it.

28-07-10, 03:21 AM
ok, little bit more info needed. where is it "weeing" from exactly? could it be that a hose is split (all be it small) and as it heats up and expands its opening up?
fans kicking in means the electrical side is all ok. it will over heat if youve lost coolant with the fans on as you will have air in the rad.

28-07-10, 09:30 AM
when it decides to loose coolant it comes out of the overflow pipes so it is not coming out of split pipes or out of the rad cap so it is all doing its job.

The bit I dont understand is that other VFR owners never have this issue, so why does mine heat up???

28-07-10, 09:11 PM
they do run hot due to being a v4, try looking for a airlock this will cause water to expand out the overflow if not you could try using water wetter drops the engine temp by about 10 to 15 deg

29-07-10, 10:12 PM
Thanx JJ, will see if I can ger some as my other idea was to get another fan to put onto one Rad and make this run all the time and leave the other one on the Thermostat so that it should still come on at 104c, this will be acheaper option (being as I am out of work at the mo).

29-07-10, 11:20 PM
I'd agree with jj seein as it is coming out the overflow. its an expansion tank, so as it all heats up the water pressure pushes it into the tank, try opening your filler cap on the radiator, blip the throttle a few times and watch the fluid, if it draws in then its filling air in the system. top it up with good quality coolant or water wetter as jj sais.

30-07-10, 07:51 AM
Sounds like over-pressure to me. This can be caused by either too much engine heat, too much coolant or a dodgy pressure release.

I'd check where the pressure release (it may or may not be the rad cap) valve is and change it. That may help. Other than that, check the thermostat.

With the fans, one option is to put a manual override switch in. That way you can turn them on when you stop.

30-07-10, 04:15 PM
It sounds like a common Honda fault to me.
Mine was sorted by ripping the cooling system apart, flushing it through and then refilling it.
Also, I found that the Air intakes were blocked by all sorts of cr*p which was preventing cool air getting into the airbox which was also a major cause for my problem so it may even be worth ripping that out and replacing your filter with a cotton one [smiley=thumbsup.gif]

I may be completely wrong because I have no understanding of the workings of bikes or anything else for that matter but I've managed to prevent a huge bill for replacement parts so it may be worth while giving it a go or even looking through a Haynes Manual the next time you're in Halfords :)

30-07-10, 05:05 PM
It's worth ditching all your current coolant and getting some de-ionised water (plus anti-freeze) to refill it - the water round here is sooo hard that the inside of your coolant chambers, hoses, water pump and radiator could well be all scaled up - I was horrified when I drained my trackbike recently so refilled it with de-ionised water (helped by the fact that a colleague's brother works in a plating factory and can get it for nothing) If they're all scaled up you'll need to flush as well as you can, and use a de-scaler where you can too. you may be able to dismantle the water pump to clean the chamber and impeller.
Check your thermostat's opening properly - a manual will explain that - stick it in a pyrex jug and pour boiling water in to see if it opens. If it doesn't open it could be the root of your problems.
Air intake and filters have nothing to do with cooling.

30-07-10, 06:19 PM
Mate if you have a V-tech
I have a pdf manual for one of those if it will help [smiley=thumbsup.gif]

PM me and i'll email it across

30-07-10, 07:44 PM
I have a Haynes book already and run through what they have said, I have also cleaned out and ran through with cleaner and refilled with water and coolant after I had the exhaust put back on.