The diary of an overheating v65

[nicklec]

Also maybe your gauge is reading incorrectly, when you say it overheats is it boiling water out into the over flow? Also if the spring on the rad. cap is weak it will release water into overflow bottle at a much lower temp. It just measures pressure and the higher the temp the higher the pressure. You might want to splurge and get a infrared thermometer, then you can real time measure what temp. your engine is getting to. Not sure if you may have a air pocket but think there is a bleeder screw on the thermostat housing. You can also feel your radiator for cool spots while it is warming up to see if there are any plugs. Also did you put distilled water in your radiator when you changed the fluid? Tap water has minerals that will cook out of it at high temp. I'll find you a link for the thermometer so you know what I'm talking about.   http://www.amazon.com/Extech-42500-Farenheit-Infrared-Thermometer/dp/B0000WU19S

[fuji]

Thank you for the extra advice nick.  I've decided to start checking each component individually starting with the radiator.  I found a site online that rebuilds and removes any clogs in the radiator.  I am not certain the radiator is a problem I just thought it would not hurt to do that.  While its disassembled I'll check all the hoses for clogs.

Does anyone know how to test the water pump?  The person I bought it from had just replaced it but I just want to double check it is working.  I know they replaced it because they gave me the old one when I bought the bike.

So far I replaced and installed brand new fan switch that goes on the radiator along with the thermostat but the fan is still not coming on when the coolant starts boiling (after about 5-10 minutes on the road).  I think there is a coolant flow problem either a clog or the water pump is not working.  Even when I short the fan for constant run it still overheats.  During all these trials I used fresh honda coolant and oil so there should not be any issues that would come from bad coolant or oil.  Even if the coolant is leaking into the oil I would expect to get a few miles on the bike before symptoms of that showed up, no?

Can anyone advise the best way to test the radiator cap for pressure.  I can't seem to find a new one online for purchase so I want to see if this one is working alright.

[fuji]

Also maybe your gauge is reading incorrectly, when you say it overheats is it boiling water out into the over flow? Also if the spring on the rad. cap is weak it will release water into overflow bottle at a much lower temp. It just measures pressure and the higher the temp the higher the pressure.

Yeah the bike is physically overheating, it may be the cap.  I heard a bad cap pressure can lower the boiling point of the coolant but there are other signs that point to something else like the fan not coming on.  I've tested the fan actuation by shorting it with a paper clip and the fan does work.  But even with the fan on constant on it still overheats.  I am starting to think it is a flow problem that the coolant is just not flowing through the system.

[TLRam1]

Without re-reading the entire post.

If the fan is not coming on you do need to trace why.

Many reasons

Not pertaining to this model.

In general.

Where does it get power and work from there to where the power is no more.

Bad Fan relay, if there is one.

Fan switch, should be able to test the switch with boiling water and an OHM Meter.

Bad fan connection, broken wire.

If you have the radiator off, a radiator shop close by should be able to check the flow and stoppages for you and perform needed repairs, if they have small enough stoppers for the openings.

Are the water pump blades plastic or metal? With the radiator on and the cap off you will see water circulate when the thermostat opens. If not check your thermostat, again in boiling water and it should open as long as the thermostat is not in backwards, thermo spring should face the motor.

Passages may be blocked in the motor.

I am short on time and didn't read the thread as to what was advised or you did. Someone might have better advise.   

[fuji]

Thanks from reading the posts I have the following list of things to do

Symptom - bike overheats rapidly, fan not coming on when hot, bike overheating with fan constant on

Done so far [X]
[X] Change oil
[X] Change coolant and flush system
[X] Make sure fan is operational with paper clip (fan is operational)
[X] Run bike with fan left constant on
[X] replace fan switch
[X] replace thermostat

In Process
[X] Check for radiator flow and clog (in process with radiator rebuild)

To do
[  ] test thermostat in boiling watter with thermometer
[  ] confirm coolant flow through hoses and engine
[  ] check water pump for operation
[  ] adjust carbs to make sure not running too lean
[  ] bleed air out of thermostat nipple
[  ] check spark plugs to look for signs off head gasket leak
[  ] Trace power source from thermostat to fan to see if there is interruption
[  ] try product rated to allow bike to run cooler than regular coolant

[TLRam1]

I would do these first.

[X] Check for radiator flow and clog (in process with radiator rebuild)
[  ] confirm coolant flow through hoses and engine
[  ] check spark plugs to look for signs off head gasket leak
[  ] check water pump for operation

Than this.

[  ] adjust carbs to make sure not running too lean

This appears to be a problem if the fan does not come on but it is not THE problem since you had it run constantly and still overheated

[  ] Trace power source from thermostat to fan to see if there is interruption

Shouldn't need this if your system is in order, to me, this is a band aide for a problem like this.

[  ] try product rated to allow bike to run cooler than regular coolant


If water flows, I would think bleeding of the system would not need to be done.

[John Luttrell]

I agree completely that it will more than likely a coolant flow problem, but I have lost track if weather or not he has changed out the radiator cap yet; a bad cap could allow the system to boil over at a drastically lower boiling point than designed to.  Possibly even boil over at a lower temp than the fan switch is set to come on.