1986 Honda Shadow VT1100C Overheating Issue

[John Hopkins]

Originally Posted by llee8300

Sorry for being stupid but I have an extra brand new fully charged battery courtesy of my stupidity. How would I run wires to the battery from the fan motor to test it that way? Or do I have to go to the battery in the bike?

If you unbolt the radiator and lean it forward there is enough room to see the two connecting wires, they actually run down the side of the radiator..or you could just go to the fuse block and one of the 10 amp fuses is marked FAN, you could connect the multimeter on the 25v dc range between the frame/ground and the fuse and see if you have 12v dc there..if you dont just run a lead with small crock clips on each end to the + post of the battery and another from the - post of the battery to the single wire that connects to the bottom of the radiator and the fan should run...

The fan is the same as a light bulb..put 12v dc across it and it will run..it doesn't matter where you get the 12v from..

John.

[llee8300]

thanks for all the replies..I actually found a utube clip on how to clean the fan motor so I took the radiator off, unbolted the fan and hooked it up to my spare battery and nothing...so I watched the clip a couple more times then took the fan motor apart, cleaned everything up real good and put it back together and tried it again and she purred like a kitten on the spare battery...changed the fluid, put it all back together and rode it till it was real hot (right at the red) and the fan still didn't come on but this time when I grounded it out on the radiator with the wire from the temp sensor it spun nicely so I think my next step will be tracking down a temp sensor/sendor or whatever that is at the bottom of the radiator...never gets too hot riding so Its not urgent to find one since I'm riding brand new fluid now and coming into the cool season...I don't do the stop and go riding in traffic but I still wouldn't mind just going with a toggle switch so I could flip it on when I get near the red...

[John Hopkins]

All good..but when you get the thermal switch make sure you flush out the radiator..you can get a build up of slimy sludge at the bottom of the radiator that insulates the thermal switch and prevents it from reading the correct temperature...It wouldn't hurt to replace the thermostat at the same time and clean the housing..

If you go for a toggle switch you should connect it from ground to the connection that you grounded..but..I leave the connection connected to the thermal switch so that I can use the new switch in heavy traffic or hot weather and still let the thermal switch work as it should..in other words I use the switch as a backup not a replacement..

John

[llee8300]

so I ordered the sensor and unfortunately ordered the one the goes at the top near the thermostat housing so took it all apart, and put it in, then ordered the the right part that goes in at the bottom right of the radiatior and put it in, then added fresh new coolant and now the fan kicks on perfectly just a little short of the "H"...good to have one problem corrected!

[pepsidevil]

Ok guys, here is what the updates are so far:

This is in regards to my original post of my bike red lining.

I checked the Radiator fan fuse, it was busted and I changed it.

I changed the Thermostat and Thermostat housing. I tested the old thermostat and it worked fine but just in case I changed both.

I changed the Thermostat-regulator at the bottom right of the radiator.

I tested the fan using JOHN HOPKIN's suggestion of shorting the Fan to start. Runs and spins fine with no problems or hiccups.

I rode around a bit the other day and still overheating. I checked the fuse and it blew out again. I read somewhere that you can up the 10AMP fuse to a 15AMP fuse just in case.

Is that a good solution or is there something else I need to find first. It seems like everything is working individually but the fuse keeps blowing out.

[John Hopkins]

Originally Posted by pepsidevil

Ok guys, here is what the updates are so far:

This is in regards to my original post of my bike red lining.

I checked the Radiator fan fuse, it was busted and I changed it.

I changed the Thermostat and Thermostat housing. I tested the old thermostat and it worked fine but just in case I changed both.

I changed the Thermostat-regulator at the bottom right of the radiator.

I tested the fan using JOHN HOPKIN's suggestion of shorting the Fan to start. Runs and spins fine with no problems or hiccups.

I rode around a bit the other day and still overheating. I checked the fuse and it blew out again. I read somewhere that you can up the 10AMP fuse to a 15AMP fuse just in case.

Is that a good solution or is there something else I need to find first. It seems like everything is working individually but the fuse keeps blowing out.

It's quite possible that the reason the fuse keeps blowing is because the fan is clogged up with debris (debree) (dirt)..when the fan get its first kick of electricity it has to overcome inertia and draws more current than when it is running, why not strip, clean, and lightly oil the fan motor and see if that cures the problem..

While increasing the size of the fuse may solve the immediate problem replacing fuses with a larger size can cause the supply wires to overheat.

All the electrical circuits on your bike are already rated to blow at double the calculated load, this is standard practice in all manufacturing so the fan circuit will draw 5amps or less and that is why you have a 10amp fuse.

John.

[cl65ame]

If the bike overheats while moving along then the fan is not the issue. The fan suppliments air flow ehn the bike is not moving. there is more than enough air flowing over the rad whn moving to keep the engine cool. Mine only runs after being stopped for a short period. You could have something else wrong like a bad pump or blocked jacket ot line somewhere.

[pepsidevil]

Originally Posted by cl65ame

If the bike overheats while moving along then the fan is not the issue. The fan suppliments air flow ehn the bike is not moving. there is more than enough air flowing over the rad whn moving to keep the engine cool. Mine only runs after being stopped for a short period. You could have something else wrong like a bad pump or blocked jacket ot line somewhere.

Usually my commute to work is about 10 minutes so it doesn't really get hot enough to be a problem throughout the year. On my longer rides, once I hit the highway an ride in Overdrive, if the temperature was hot or close to the H it drops down after a few minutes to mid way between cold and hot and stays constant, which I think is the ideal temperature.

I think that because it is able to keep constant when i'm not riding in traffic, I'm assuming the pump is working well and I've already replaced and tested the thermostat and it's housing along with the radiator cap.

It seems like my bike heats up obviously when i'm stuck in traffic but the fan doesn't go on, it seemed to be blowing the fuse.

[pepsidevil]

Originally Posted by John Hopkins

It's quite possible that the reason the fuse keeps blowing is because the fan is clogged up with debris (debree) (dirt)..when the fan get its first kick of electricity it has to overcome inertia and draws more current than when it is running, why not strip, clean, and lightly oil the fan motor and see if that cures the problem..

While increasing the size of the fuse may solve the immediate problem replacing fuses with a larger size can cause the supply wires to overheat.

All the electrical circuits on your bike are already rated to blow at double the calculated load, this is standard practice in all manufacturing so the fan circuit will draw 5amps or less and that is why you have a 10amp fuse.

John.

John,

I tried cleaning off the fan and lubricating the motor a bit. I took a paper clip and attached it to ground going to the thermo-regulator at the bottom of the radiator. The fan turn on and ran fine, the fuse did not blow and I left it running for about 2-3 minutes just to test.

I still had the old thermoregulator which I tested with boiling water and then a lighter to heat up and then it started creating continuity so it was working, the one I have in the bike now is brand new so i'm assuming its working too.

My question is why is the fuse blowing? The fan runs with a new fuse when I bypass the thermo-regulator, no shorting.

I was thinking possible to just add a switch and bypass the thermo-regulator all together of have it as a backup.

Any ideas? It's strange that the fuse blows while i'm riding but not when I test the unit.

Also on a side note, when I changed my thermo-regulator with a new one, the coolant was crispy lean with no signs of gunk or blockage. Still looked like gatorade.

Let me know if you have anything else in mind for me to try.

[John Hopkins]

Look the fan works like this, you have a supply from the + terminal of the battery to the ignition switch, from there to the fuse and from there to the fan..that is the live side..

The return side or ground side comes out of the other side of the fan and clips onto the thermal switch and out of that to the ground..

OK fuses work by overheating as they draw current which means amps..and that is why they are rated in amps...the thermal switch is a thing called a thermistor..that is a resistor that changes it's resistance as the temperature changes..because of a simple equasion called ohms law E = IxR where (E) is fixed at your battery voltage when (R) (the thermistor and the leads, fan and connections) changes the current (I) will change..So your possible causes are sticky motor, incorrectly working thermal switch loose or dirty ground connection or any poor connection from the battery through the switch to the fan..I have had a high resistance connection on the switch which caused the contacts to burn..I cured this by disassembling the switch and building the contact back up with solder.

That's all I can tell you.

EDIT:-
I forgot to mention that the ground of your bike is from the - of your battery to the frame, engine and radiator..all of those points should be linked and you can prove this with a multimeter set to Ohms with the ignition off. you should short each point with a length of copper wire prior to measuring because if you have a voltage leak in the circuit you will damage the meter.

John.