Jump to content

2006 Vfr800 Overheated - Cooling Fan Did Not Turn On


vfrmike06

Recommended Posts

Had a scary moment today, bike generally seems to run a bit hot but it actually overheated today because the fan never triggered on. Wanted to get some thoughts on potential causes/things I need to fix.

So here's what happened:

It was about a 28C day today, "feels like" 35C with humidity (according to Weather Network). Took a 20-minute ride down the highway in the city and then pulled off onto a downtown city street. As I pulled off and went from 120km/h to 70km/h, the engine temp gauge was indicating about 105C-110C, which was odd because at highway speeds on a summer day, it'd usually be in the high-80C's or low-90C's. I just shrugged and thought, "well, it must be a hot day today."

As I was stuck in stop-and-go traffic, the gauge kept on creeping up, but I attributed it to being a hot day. Then the gauge crept up past 120C, then 122C, and then the overheat indicator light came on and I started getting scared. I was stuck in moving traffic for maybe another 20 seconds, and then hit a red light, so I cut the engine ASAP and coasted to a stop. The temp gauge kept on creeping up to 128C, and so I bent my head down and confirmed what I thought - the cooling fan wasn't running.

I turned the ignition off, waited a couple seconds, then turned it back on. Immediately, the fan started running. I think after about 10-20 seconds, traffic started moving again so I started the bike up and rolled it down the street at about 30km/h, but as I did, the temp gauge pretty quickly (~30s?) dropped down to 119C, and then down to about 115C. (this is kind of a panic-blur in my mind, to be honest)

I pulled into my apartment garage shortly after (maybe 5 minutes after the bike first overheated), and after pulling it into my parking spot and cutting the engine, I left the ignition on so the fan could keep doing its work. After a few minutes, the engine temp was brought down to about 110C, and at that point the cooling fan stopped spinning. I tried turning the ignition off and on a couple of times, just to see if the fan would start again, but it didn't. If I recall correctly, in the past, the fan would continue to run at 110C until it got it down to below 105C.

Even at 110C, after the fan stopped running, I could actually hear the coolant boiling and bubbling. The right fairing was also very hot to the touch. As the temp gauge dropped closer to 100, the bubbling simmered down and I didn't hear much anymore (as expected).

So, all that being said, I'm planning on bringing the bike into a shop tomorrow and getting them to do the following:

- check/replace engine temp sensor

- coolant flush and refill

- replace rad cap

- check for any signs of overheat damage visible

Is there anything else I should be aware of, or get the shop to do while they're in there?

Is there a way I can get the cooling fans to trigger at a lower temp just to be safe?

Thanks all!

Link to comment
Share on other sites

  • Member Contributer

When I bought my 2002 bike with 52,000 km on it and drove it for the first time in the city I didn't like the way the temp climbed up to 120 centigrade when standing still in traffic. Remember though that this is the temp in the V of the engine block not the temp at the switch in the secondary radiator. I tried a new switch, a new sender unit and completely flushed the system and refilled ensuring all air was removed. It did provide a slight improvement in cooling but not to the reduction I would like to have seen so I decided to try a few things:

1. I mounted a secondary fan on the primary radiator and switched this with the other fan. It helped to cool the engine when in traffic but at speed I found that it actually reduced the cooling effect of the air flow so I removed it.

2. I removed all of the hoses and radiators and aluminium connectors that mount the hoses to the engine. I couldn't believe how much crud had built up and been deposited on the internal bores of the aluminium. This basically reduces the flow through the system and produces turbulent flow. Ideally what you want is laminar flow. The water pump inlet and outlet were both the same so off that came and I fitted a wire rotary brush to my dremell and blasted it all off. I then realised that the internals of the engine will be the same so investigated in a proper chemical cleaner to get rid of this build up. I found this company and it worked wonders. Bonus is that it will not damage aluminium, brass, copper, silicon or rubber http://liquidintelligence.com.au/products/engine-cooling-system-cleaning-kit I also bought their Waterless coolant for bikes. This stuff wont boil until it reaches 190 Centigrade which means the coolant is always in contact with the walls of the cylinders to transfer the heat http://liquidintelligence.com.au/products/motorcycle-super-waterless-coolant

3. I then decided that I wanted to switch the fan on earlier so purchased an electronic thermatic fan switch from Davies Craig https://daviescraig.com.au/product/digital-thermatic-fan-switch-kit-part-no-0444/digital-thermatic-fan-switch-kit-part-no-0444 This allows you to set any temp digitally from 40 - 110 Centigrade to switch the fan on. It has all of the relays fitted and will actually power two fans, the second one starting 10 sec after the first one starts. As I had removed my second fan this is redundant. I decided to fit the temp probe into the fins of the primary radiator so it is sensing the temp of the water coming directly from the engine block.

Since I have done this I have no cooling issues at all. Highest temp I see in town is 108 C and on a steady cruise down the highway I get 79 C

Tip for getting air out of the VFR cooling system is to use the Napa spill free funnel. It connects via a radiator cap adaptor and you can leave it fitted with the bike on the side stand whilst letting the bike run at idle to get the temp up to open the thermostat. You will not believe how much air is trapped in the engine when you do a complete coolant change, especially once the thermostat opens. Once all of the air is out let the system cool with the funnel still connected. Then when totally cold top up the system with coolant and remove the funnel and fit the rad cap.

http://revlimiter.net/blog/wp-content/uploads/2011/03/DSC_1249-590x392.jpg

Link to comment
Share on other sites

  • Member Contributer

If the coolant level is a bit low,the fan switch may not be submerged in coolant (it's at the top of the left side rad) and won't sense the heat sufficiently to turn the fan on. That could be part of the issue.

Link to comment
Share on other sites

Thanks for great the write-up, Marooncobra! I learned a ton.

I think I'll start with checking the coolant levels (as per Cogswell), burping out the air with the no-spill funnel as you suggested, and then moving on to trying out the Liquid Intelligence and adding a fan switch if necessary.

Quick update: on the ride to work this morning (standard city light-to-light stuff), things seemed fairly normal. It was a humid 25C this morning, kept the ride nice and easy (shifting around 6000rpm, cruise around 5000, easy acceleration). Bike crept up to 100C+ as I rode, but fan was running this time as it got up around 105, and when moving it brought the temp down to about 100C. When I parked the bike, it crept up to 110C, and fan worked to bring it down to 109C before shutting off. No boiling coolant this time *thumbs up*

Link to comment
Share on other sites

  • Member Contributer

You have air trapped where the fan thermoswitch is mounted in the lhs radiator.

Burp that baby. Be sure to burp it while on the side stand, it's more betterer... The bike that is, not you.

I also expect this is the case. And, along with adding the coolant while on the sidestand, it also helps a lot if the bike is on an incline (with the front end higher than the rear). The idea is that you want the fill point (the radiator cap opening) to be the highest location in the system, therefore allowing all of the air to escape.

Link to comment
Share on other sites

  • Member Contributer

Marooncobra: does one of the caps with the NAPA no spill kit fit the vfr? It looks like a great idea.

Yes, the kit comes with a number of different sized radiator caps. Once you fit the cap and plastic adaptor that has a rubber gasket on it you then push fit a bend on and then the funnel. When the bike is on its side stand and the steering pushed over to the left the funnel sits upright. You then fill with coolant and actually overfill it as the excess sits in the funnel. It probably holds 1.5 litres. Don't fill the funnel to the top as when you start the bike to remove the air you will see the level of coolant rise in the funnel due to thermal expansion. Bubbles will escape and when you get to about 82 centigrade and the thermostat opens you will actually see the coolant level drop. This wil continue between rising and dropping until all of the water reaches 82 or above to keep the thermostat fully open. You can blip the throttle during this time as well as it does help. From memory I also held a constant rev of about 2000 for 10 - 15 secs which also helped to get rid of air. During this time also you may need to add more colant to keep a level of water in the funnel. It is also during this time that the air escaping looks like fizzy water. As the system is not under pressure and the funnel allows for thermal expansion of the water you will not be scolded with water. At times you think you must have a leak as small bubbles still keep coming out. Just keep going with running the bike until it all goes. Once all air is out turn off and let the bike cool. You will be suprised how far the water level drops once cold so stand by the bike during this time keeping the coolant level just above the bottom of the funnel. Once totally cold remove the funnel, top up and fit the radiator cap. When the funnel radiator cap adaptor is fitted the expansion bottle does not get any coolant so don't think you have any air coming from there, it is all coming out of the engine. Once you have watched this process you will realise that a lot of people who have overheating issues is through air still being in their coolant system.

I bought my funnel off eBay but I understand that In the USA you can get them from the larger car spare shops.

Link to comment
Share on other sites

Might I add into this to have your radiator cap checked? I had a cap that slowly went bad and it displayed the exact symptoms of the OP. It cost a total of about $7 to fix it with a new radiator cap from Autozone. Unfortunately, this was after the coolant leaked into my resevoir and overflowed onto the left side of my tire, which then lowsided in a turn. My ignorance of the problem caused thousands of dollars of damage to my pristine 05 for want of a part that is less than $10.

Link to comment
Share on other sites

  • Member Contributer

I'm glad to see that my cooling system is still working well after 90,000 km. It is a hot bike and I always get paranoid on hot days in the city. I almost never see the temperature climb above 104°c.

Link to comment
Share on other sites

Lint - ouch! Sorry to hear that man - hope you were able to walk away without too many scratches/bruises

My bike gets above 104C as a regular occurance, but not often above 110C.

Thanks for the heads-up on the radiator cap. I bought a few liters of MotoChill and plan to do a coolant flush, as well as getting a new drain washer and radiator cap. Also plan on putting the bike through a few heat/cool cycles on advice from a local mechanic, burp it out, etc.

The radiator no-spill funnel looks like a great idea. Canadian Tire doesn't seem to carry the kit, so I'll have to find another place that does.

Link to comment
Share on other sites

Lint - ouch! Sorry to hear that man - hope you were able to walk away without too many scratches/bruises

My bike gets above 104C as a regular occurance, but not often above 110C.

Thanks for the heads-up on the radiator cap. I bought a few liters of MotoChill and plan to do a coolant flush, as well as getting a new drain washer and radiator cap. Also plan on putting the bike through a few heat/cool cycles on advice from a local mechanic, burp it out, etc.

The radiator no-spill funnel looks like a great idea. Canadian Tire doesn't seem to carry the kit, so I'll have to find another place that does.

Yep, walked away fine, thanks to ATGATT.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...

Important Information

By using this site, you agree to our Privacy Policy.