03 VFR800 Coming Soon

Still not cooling properly. I'll be doing 60mph and the temp will climb to 220+ in 40°F weather. New thermostat, new rad cap, fresh coolant. I think I bled the cooling system properly, it's still not making sense. If I shut it off for a minute or two, and fire it back up, the temp will be at 190 and continue to drop to 180s. Then it will climb back to 220+, and it will drop here and there. My idle is fussy again, cold start it will idle around 2k then climb up to 4k and idle around there. I think having the extreme idle is making it worse. It leads me to believe theres an air bubble, because my idle was great prior to draining the coolant and refilling. Or my temp sensor is giving me trouble. I'm going to try an infrared thermometer or whatever they're called today.

 

Sorry to hear that you're still having troubles Jake. The varying temperature readings sound very odd, as the new thermostat should be controlling the flow to the radiator and keeping things steady, especially at speed in cold weather.

Your idea of checking the actual radiator temp with an IR thermometer is a good one. Maybe you've just got a dodgy connection for the engine coolant temperature sensor (plugged in to the back left of the front head)? The fan operation is completely independent of this (it relies on its own switch mounted to one of the radiators) and should be coming on around 210-220, so if that is not coming on it might point to the ECT sensor or its connection.

I'm not a big believer in bleeding the coolant system making any real difference; the expansion line drains off the high point, so any air should accumulate there and get released to the overflow tank. There's also an air bleed line from the thermostat to the radiator that allows air out.

Did you positively check the wax unit lines are clear and flowing? If not, there is the source of a high idle.

 

The engine temp reading on the IR thermometer was very close to the LCD readout. I went on a ride today, my idle dropped back to 1200 RPM and that helped with the temp when in traffic. The fan operates correctly, but it is still running warm. I need to pull the radiators, give them a good back flush, as well as make sure the fins are free of dirt and oil. I guess I should pull the water pump cover just to double check it. I'll order a gasket and check it when that comes in.

 

Actually Terry, when I used the IR thermometer I checked all over the front head near the exhaust ports. My amature brain didn't even think to check the radiator reading at the supposed 220 degrees. Of course the exhaust side of the head is going to be warmer than everything else, it might just be a coincidence it was very close to the gauge temp. At 220 degrees the thermostat should be wide open with water circulating 100%, so the radiator should be near exactly that when idling at stand still. I may just be taking the slightest of errors and turing them into big hope, but that makes a lot of sense in my brain. I'll double check my error tomorrow.

 

So a loose connection, bad switch, or corrosion will add more resistance, leading to a constant 35°F or so addition to the temp reading. That makes a lot of sense, but at the same time, my fan came on while reading 225 I think. So both switches would have to be bad in order for my theory to be correct... I'm sure those odds are slim, but I'll double check when my fan turns on as well as my radiator temp. I wanted another VFR so bad, but I would like to ride it without constantly checking my temp gauge!

 

Actually, a higher temp corresponds to a lower resistance, so corrosion would make the gauge read low, not high.



Maybe getting into a decent radiator flush makes the most sense, as does checking the water pump. I'd think there would be a way to check the pump flow while it is still installed.

 

Oops, my mistake. It would be tough to get low resistance any other way than a bad sensor. I'll see what I can do about the radiators today at work. I can't back flush them at home because I don't have hosee access at my apartment. Pulling the cover on the water pump would be easy enough just to make sure the turbine is in good shape and spins as it should. I guess I'll spray some sort of degreaser in them then spray it out. I really don't want to take my fairings off after I just put them on!

 

Gauge read 225-230°F and the hottest spot on the radiator tank I ever picked up was 197°F for a brief second, I never could get it to read that high again. That was at a stand still with the fan disconnected. It hung around 225°F for a long time with no fan, the temp reading was 186°F for the most part are the IR thermometer. 186°F or so is the T-Stat opening right? That would make sense why it stayed around that temp for the most part. The temp outside was 45°F or so. I'm hoping I found my problem...

 

I hope so too.

The temp sensor reads higher with lower resistance, so if you have a chafed wire that allows some grounding to occur you'd get a higher reading.

Just a suggestion, but the VFR's are known to have a ground block fault; there's a terminal block about 1" x 0.5 x 0.5 taped into the harness where a lot of green wires terminate, that can suffer corrosion. Poor earths lead to all sorts of issues, a common fix is to take the block out and solder the wires together then terminate them on the frame.

I'm a 5G guy so I know the earth block on my bike is orange and on the left rear, the 6G block is blue (I think) and located in the top fairing somewhere.

 

When you say top faring, do you mean around the headlight?

 

This blue connector and green wires? Or is there other ground block of sorts I'm missing?

 

Have a look at this thread:

http://www.vfrdiscussion.com/index....-gen-blue-connector-ground-fix-how-to/&page=3

 

Thanks, I read through that one when I found that photo. I'll take a shot at that one of these days, being that I'm not risking the motor or anything, I'm not as concerned anymore. I really appreciate all the help everyone here has given me, I'll be sure to pass it on.

 

It's still having problems. Now it's climbing up into 235-240, and it popped a hose off of a radiator inlet (the clamp was loose) as soon as it popped off the temperature gauge dropped 20+ degrees. Made another ground for the green wire, and it didn't change anything. I'm starting to lean towards a head gasket leaking combustion pressure into the cooling system, I don't have any mixed fluids though. As much as I wanted It to be anything but a head gasket, I really need to consider it. It doesn't smoke, no fluid mixture, but excess pressure in the cooling system it seems like. Obviously the more heat in the cooling system, the more it will pressurize, and the pressure issues are directly related to the higher temp level. The fact that the temp dropped a large sum right when the hose blew off, is confusing. So either the radiators are so clogged, it's extremely inefficient and getting worse, or my head gasket is leaking and it's getting worse. I'm about to just bail on It and claim insurance...

 

Pulled my radiators and fan. Back flushed the radiators, and my fan was too close to the radiator causing it to rub and not spin at max rpm. Put it all back together and still the same issue (I tightened all my clamps 2 more were loose]. I found something else out though. The front of my radiators (where the water enters from the warm engine) at 240°F were scalding hot. The rear of them(after flowing through the fins) were cool to the touch. The hose from the thermostat was hot, but every other hose after the radiators were cool. That's why my IR thermometer reading was wrong, that part of the radiator was cool. So I'm leaning towards water pump problems. I'm going to drain my fluid again and pull my water pump cover. If that's not it, radiator replacement I think.

 

This was my feeling way back in the beginning of this thread. Old man said this in an earlier post because there is usually a reason a seller leaves the radiator cap off...it's a red flag to those of us that have been there, done that. Blowing hoses off is a pretty good sign you have a blown head gasket pumping air into the system IMO. They don't always mix fluids if the breach is between combustion chamber and water jacket. Sorry.

Edit: The fluctuations in temp and the drop in temp when the hose blew off are indicative of a head gasket also. Air is being pumped into the cooling system. this creates air pockets (locks). When the hose blew it relieved the air lock. Pretty much every symptom you have is an indication of a blown head gasket...although I would check the water pump seal just to be sure it's not leaking there. Usually the water pump doesn't give these symptoms tho.

 

Jake has reported elsewhere that he has found the water pump drive coupling was sheared. Not sure if that will be a root cause for the cooling problems.

 

That would do it. Not a very common problem in my experience.

Glad I told him to check the water pump.