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Offline Roybill

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Running too hot?
« on: 12 December, 2019, 10:31:22 AM »
Bought second hand mark 1 2009 CBF1000A end of September 2019. Suspicious smell of fuel for the first couple of weeks at least not the same smell as my fazer. Talked to prev owner and he hadn't changed spark plugs recently or anything of that nature. It was Like a steam engine in Rain; didn't know whether Rain or coolant but enough steam to fog clocks and mirrors. Contacted prev owner, no known issues. Eventually on week 4/5 got overheat light. Stopped and brought to workshop. Took off lower fairing. Took out thermistor. Overheated again. Bought brand new Honda radiator and pressure cap.  Replaced coolant for the third time. Fan coming on and cutting off when finished. Checked this for 15mins. Been riding through traffic for 25km each morning and each evening. The bike smells like its on fire (really hot), 4 days later I need to top up the coolant again. No overheat light but steams like an old steam engine in the rain this morning. I put it on side stand and a torrent of liquid (I hope rain water) came gushing off radiator. I can feel a ridge on top of radiator. Does any of this sound familiar. Is there anything I can do to reduce the heat of this thing? :110:
« Last Edit: 12 December, 2019, 11:03:31 AM by Roybill »

Offline Art

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Re: Running too hot?
« Reply #1 on: 12 December, 2019, 06:33:05 PM »
New radiator and cap would suggest you can rule those out. Question is what led you to replace those? You've had the thermostat out did you test it? Have you re-fitted it? No need to keep replacing the coolant, assuming its recently replaced with the correct 50:50 mix of the correct coolant just drain it off into a suitable container and re-use it. You say the fan is working so the fan relay should be OK too.

I'd start off checking the coolant level, air locks, leaking hoses, blockages in hoses or cylinder block, water pump operation and coolant temperature sensor.

Section 7 of the workshop manual is your best friend, it covers the Cooling System. Download it for free here https://bob.ollis-brown.co.uk/manuals/cbf1000/
« Last Edit: 12 December, 2019, 06:38:48 PM by Art »

Offline Roybill

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Re: Running too hot?
« Reply #2 on: 12 December, 2019, 08:27:14 PM »
Thanks for that. Thermostat was not working, not needed for basic operation just means unrestricted coolant flow and theoretically means that bike takes longer to warm up.....this is not a problem with this bike, so haven't installed new one yet. I drove home this evening with no problems. Let sit idling for a few mins and fan came on; then subsequently shut off, so that sounds correct. Ye maybe a restriction in the overall flow but where to start? Would a damaged  head gasket lead to these problems. There doesnt seem to be any loss in compression and no funny smoke from cans. Just seems so bloody hot and this makes me nervous  :034:
« Last Edit: 12 December, 2019, 08:28:22 PM by Roybill »

Offline Art

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Re: Running too hot?
« Reply #3 on: 13 December, 2019, 05:40:19 AM »
What leads you to suspect the head gasket?

Offline Roybill

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Re: Running too hot?
« Reply #4 on: 13 December, 2019, 11:31:20 AM »
A mixture of paranoia and ridding my mind of nightmares, but also the fact that the overheat light had come on before i changed the radiator and cap has me considering all sorts of scenarios. I tested the bike again this morning. Started cold and left idle. Not too much smell but maybe i'm being too critical here. Fan kicked in after 15mins and ran for 20-30secs then turned off. Fan kicked in again a few mins later. On both occasions i could feel the cold being drawn into the rad and i could feel the hot air coming off of the rad, so all good there. The coolant in the expansion tank started at the cold mark i made and expanded (oops) to just under the mark i made yesterday when it was at its hottest, so all good there. The very normal looking steam coming from the cans dissipated after about 5 mins and no smoke from there (yay). I then tested the water collection by simulating rain with a hose  :112:. Wet the bike when running on centre stand and sure enough steam fogged up clocks and mirrors. Sprayed diffused water directly at rad for a 20 secs. Put on its side stand a bit of water pouring off but nothing like yesterday's torrents. Turned off bike put on centre stand and simulated rain for a longer duration (hope neighbours were not watching). Sprayed diffused water directly at rad and thereabouts for a longer duration also. Put on side stand and lots of water pouring off but not as impressive as yesterday; maybe the hotter water pours better? It looks like its accumulating in the rad core and possibly above on a rubber mat that is installed over the rad and maybe on the rad itself (there is a ridge up there that wouldnt help). I saw a contribution from somebody who installed a mudguard extender and this reduced the problem by reducing the amount of road spray going into the rad core. This looks plausible (and a good idea) because the front mudguard is a little short, so that is my next port of call. It is most likely therefore that the bike is operating as it should and hot as has been indicated by others? Kindof stuck with it so and not looking forward to hot summer days if they occur  :006:

Offline Art

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Re: Running too hot?
« Reply #5 on: 13 December, 2019, 04:06:45 PM »
Welcome to the forum then Roy.

Ah yes Paranoia, wasn't that Willy Nilly's old regiment? Don't panic Mr Mainwaring you'll see a bit of that around here from time to time.

Happy days

Offline ramiller

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Re: Running too hot?
« Reply #6 on: 13 December, 2019, 09:02:19 PM »
Can confirm I freaked out the first time I washed mine, gave the radiator a blast with the hosepipe and when put on side stand I bet there was nearly a pint of water flowed out!!
But now I know it’s perfectly normal

Ride safe.

Bob M

Offline Roybill

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Re: Running too hot?
« Reply #7 on: 14 December, 2019, 11:12:38 AM »
I timed how long the rad takes to clear a full dose of water after a 'good' wash using RIP...oops sorry MUC-OFF - 11mins. So after wash/lots of rain need to leave idle for ygat time and hope it doesnt rain  :152:. I shall report back about mudguard extender.....whether you like it or not :123:

Offline Art

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Re: Running too hot?
« Reply #8 on: 14 December, 2019, 01:07:55 PM »
The mudguard extender is a must have modification to the front end. It will reduce but not altogether eliminate the amount of road fling hitting the radiator. Which means that the cleaning & straighten of the radiator fins is more or less confined to a central section that extends about 3" wide and 6" up from the bottom of the radiator. That doesn't mean the rest of the radiator fins can be ignored as these will still receive their fair share of airborne debris.

edit:- Note there's nothing magic about a mudguard extender and the road fling no longer landing on the radiator has to go somewhere and can be found further back on the underside of the engine and centre stand.
« Last Edit: 14 December, 2019, 01:17:27 PM by Art »

Offline Roybill

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Re: Running too hot?
« Reply #9 on: 14 December, 2019, 02:07:31 PM »
Nice one Art, it immediately looked like a no brainer  :062:
« Last Edit: 14 December, 2019, 02:09:12 PM by Roybill »