CBR 1000 F overheating
 

I have a CBR 1000 F 1990 model. It is constantly overheating when running warm. Fan kicks in. I have changed the thermostat, the assy unit (the sensor of the gauge on back of the thermostat house, and the sw.assy thermo unit on the radiators lower end. Still running hot and spitting some coolant from expansion tank. Gauge needle going way over to the right end, passing the red area. What can I do next? Regards Tor Norway.

G'Day Tor and welcome to the forum.

I'm assuming you have flushed the radiator/cooling system? That would be my first action, then check the radiator cap is in good condition - they are cheap to replace. Make sure the radiator is clean, i.e that air can flow through the fins easily - blow it out gently with an air-line. Then look at the water pump.

If all that is done and it is still overheating I would be suspecting a blown head gasket.

Swing by the Hurricane forum and introduce yourself.

Cheers, SB

Oh and don't forget to.........

Please Vote for the CBR1000F and Sebastionbear for the September 2012 ROTM

Welcome, Sorry no help here cept for the CBR1000f linky. :)

CBR 1000F "Hurricane" - CBR Forum - Enthusiast forums for Honda CBR Owners

CBR 1000 F, 1990 overheating
 

Spent this week-end troubleshooting the problem. My son who is a sertified mechanic assisted me. We flushed the coolant. It had a clear, blue color, no traces of oil in it. Oil clear with no signs of milky color, could mean no water in oil, i.e hopefully not a broken head gasket. Disassembled water pump. It was intact running freely, and we could see that water was running/flowing in the radiator house when engine running. Blowing the radiator cells with an air gun. Blowing the empty radiator inside with an air gun. Re-filling the system, gurgling it as much as possible, removing all the air from the system. Conclusion: no fault on water pump.

Have not changed the radiator cap, but it seems allright. It stopped spitting out coolant, since we found a loose hose clamp.

We are suspecting some kind of an electronic failure, based on the following: When we are loosening the wire of the sensor on back of the thermostat-house, which leads to the gauge, and connecting it with earth i.e to the frame, the gauge needle immediately jumps to the far right end, as far as it can.This is the same that happens after driving the engine hot: The needle first stays in the left area, then moved a little from left to right and back, but always inside the recognized area. I´ve just been driving it for a few minutes, and when returning to my garage, I am letting it idling a while to see how it appears. Suddenly, the gauge needle jumps to the far right end, staying there. It won´t return as long as it runs standing still. Fan kicks in, but stops as if it reaches a tolerable temp.

We find it odd that the needle jumps up suddenly. It should possibly move more gradually to the right. It´s odd that the fan stops. If it´s overheating, we think the fan should be running constantly.

Could this be a failure with the wire from the sensor to the gauge? Could it be corroded and touching ground somewhere? Is the engine really overheated or are we cheated by a gauge failure? I do not have an infra red thermometer, so how can I measure the temperature of the coolant?

Or is it the worst: is this behaviour typical of an engine with a broken head gasket?

We are running out of ideas, and I am soon tempted to see a garage dealer to troubleshoot professionally.