Cooling fan blowing fuses

I am having an issue with my 1986 VFR799F2 blowing fuses. I think this has been an issue before as the PO put in a 15A fuse(purchased in 1994) and it takes 10A. I recently restored this bike after parking it in 2002. I do not recall any overheating problems so it might be an aging fan.

When I jumped the fan to ground it works fine but the lead gets hot fast. Today it blew the 15A fuse again and boiled into the overflow tank. It runs cool on the highway. I checked the connections last week and they were clean. I cleaned them just to be sure by pulling the wires from the connector and cleaning them. The fan switch was working last week also.

The big problem is that no fan is available. The same fan is used on several of the 1990's bike also. Any ideas on what to check before I go to the trouble of pulling the radiator and fan? I think there was 12vdc going into the fan with the bike off and key on.

After check the voltage at the connector with the bike running it is 13.8vdc. When I jump the fan to ground it is 9.9vdc and the jumper gets hot like right now. Any suggestions on this issue would be greatly appreciated. And any idea what new fan might work on this bike? Eddie

 

Sounds like some windings in the motor are shorted, if fused at 10 and it blows 15A, something is definitely wrong.

I checked Partzilla for a 1986 VFR750F (didn't see 799F2) calls for part number 19030-ML7-024 fan motor by Matsushita (not available new)

 

Thanks Allyance,

I think you are right. I am pulling the fan this weekend and checking it over. I may be able to disassemble it and repair it. A new fan may be hard to find. I checked Partzilla earlier and the 3rd gen bikes use the same fan for a few years also. They did not know what else will fit.

 

I know you say your fan works, but maybe you've got a little debris or something that is restricting the easy rotation of the fan? The fan on my VTR would spin but not easily, as the shroud was distorted by a hose jammed between the frame and shroud, and it blew fuses until I removed the hose.

 

Cadbury,

Thanks for the help.
I pulled off the radiator and fan last night. The fan turns easily. There was nothing lodged in the fan before disassembly. I am going to hook up a 10A fuse to it today and run it. If it blows the fuse it has an internal short. The wires from the fan looks pinched in a few places also but no breaks or burnt areas.

Does anyone else think this fan is getting too much voltage at 13.8v? Everything else is working perfectly. I did replace the stock RR with a RM brand MOSFET RR recently but the fan was blowing fuses before this and the stock RR was good. The stock RR was getting to a temp of 225F and the new one is only getting to 136F for reference and around 14v charging.

 

I doubt a 1 volt change is going to bother a robust dc motor. More than likely a failure in the enamel coating of the windings which cause the copper wires to overheat, making it self destruct.

 

Definitely on the winding boat. Electric motors can crap out too. You may not be able to go oem, so why not upgrade? Get yourself a similar diameter, brand new one and rig it in there. Good luck!

 

This morning I hooked the fan motor to a battery with a 10A fuse. I almost immediately blew the fuse. It must be internally shorted like you suggested and not a wiring issue. It is time to find a new fan motor. I may be able to use a newer model motor as Honda used the same fan on many of the VFRs with a different motor part number and they look similar to this one. I am actually glad it is the motor and not a wiring problem. I definitely want a new motor also. Thank you for the help on this one.

 

I took a chance and found a 1995 VFR fan assembly on Ebay that I thought might fit. This fan motor is still available from Honda for about $225. It uses the same fan as the 1986. Saturday the assembly arrived and was tested. I removed the motor from the 1995 frame and it fit perfectly in the stock frame. The leads needed to be extended except the lead going to the thermosensor. I assembled the fan on the radiator and installed it. Everything else was reassembled. I retested the fan again and went for a ride. The fan kicked in while riding in town and I kept riding to get everything as hot as possible.

The bike has been on a few test rides with the 1995 fan motor and is still functioning perfectly. Fan-tastic feeling to get this bike on the road and reliable again! I will post some pics later. Ed

 

Sometimes the "parts-bin engineering" practices employed by motorcycle companies really helps.