Stuck on overheating issue - 2008 Jonway yy250t-2 (244cc) By tumbleweed (Read 1,596 times)

[tumbleweed]

Just before Thanksgiving I purchased a used 2008 Jonway yy250t-2 (244cc) for $1000.  It seemed to run well, so I rode it home, about 125 miles.  I knew nothing about the mechanics of a scooter, and hadn't ridden any kind of motorcycle for 43 years, so this was a fun ride! I noticed the temperature gauge getting up near the top 3 or 4  times, so I stopped to let it cool and added water as needed, then continued on.  Other than a flat tire due to a bad tire stem, it was a great trip.

A few days ago, after driving around the area a bit, I decided to do a PDI. At first I thought I'd just replace all the fluids, hoping a thorough cleaning of the cooling system, and refilling with 50/50 coolant and water would solve the overheating issue.

After reading extensively on the forums, I decided to go the whole route with the PDI. I have all the plastics off, have changed all the fluids, and have cleaned and burped the cooling system as per your instructions. At this point, I'm having some problems:

1. Coolant doesn't appear to be "flowing" when I watch with the coolant cap off. This baffles me a little, since both the upper and lower hoses are getting hot. I boiled the thermostat and it's working. I took the cover off the water pump to inspect the vanes and check for any junk that might be hidden in there. It all looked good.  I didn't know how to check to see if the pump was working, so I skipped that.
2. Even though the radiator fan was working when I bought it, it only worked once when I took it on a test ride, but I don't think it ever ran again.  As part of the PDI, I crossed the wires leading to the thermo switch once, and the fan went on. Then,after I did the burping, etc., and heated things up as described, I couldn't get the fan to come on when it seemed it should have. I decided to test it again. Only problem is...I did it wrong this time, and ran a hot wire from the battery to the two thermo switch wires. I got a spark and melted the clear plastic protector for one of the female connectors a little. I tried touching with the hot wire again and this time I got no spark. Now, when I touch the two thermo switch wires together, The fan doesn't operate. After looking at the wiring diagram it appeared to me that there may be an in-line fuse on that wire, but I don't see one, and don't know how to find it.

I need HELP!!!  Do you think you can help me?  I don't know what to do next.

Thank you for the wonderful service you provide!!!

[tvnacman]

fuse box under your seat I think .

John

[skyrider]

Based on my experience with a 2011 YY250T I'm guessing that your temperature gauge is bad. That was the problem I had, replaced the temp sender twice with no change. It did not run hot at all and the fan rarely came on, just in city traffic in hot weather.

[alleyoop]

Find the fuse box, the cooling fan has it's own dedicated fuse and it is probably blown.
Alleyoop

[tumbleweed]

Thanks for the replies John and Skyrider. I've checked the four fuses in the fuse box under the seat. They all appear to be good. I Also checked them with a multimeter by touching the negative wire to ground and the positive wire to one side of each fuse, then the other (am I doing this right)? All four checked out at 12V on both sides. The problem seems to be in the wires running to the thermo-switch. Do they complete a circuit between the fan and the main on/off switch? Looking at the wiring diagram, it appears that there's an in-line 10A fuse on one of those wires, but I haven't been able to locate it. Is there a way to see if touching those two wires together is completing a circuit?

skyrider - So if I'm getting this right, there's a temp guage on the instrument panel, a temp sender coming off the thermostat housing going to the guage, and a thermo-switch on the bottom of the radiator. Do I have this right? The thermo-switch completes a circuit (pos or grnd) that turns the fan on or off?

When it overheats and I turn the motor off, hot coolant is being forced out the cap for the overflow bottle.

Can anyone tell me how to test the water pump?

[tumbleweed]

Does anybody know how I can move this threat from "non-Chinese" to "Chinese"?

[tumbleweed]

Well, I removed all the plastics from the front, looked for in-line fuses, and found there are none. Maybe I was reading the wiring diagram wrong. Then I went back and checked the four fuses in the fuse box. All OK. Next I removed the entire fuse box. When I checked the wiring underneath I discovered two problems: A) the location of the fuse for the fan was different than the one indicated on the diagram shown on the inside of the box, and B) one of the female receptacles for the fan fuse had been pushed down and wasn't contacting one of the male prongs from the fuse. (Now I remembr reading on a post by another member that this could happen). Tested the fan by crossing the wires leading to the thermo-switch. FAN WORKS!

Next I decided to double-check the thermostat to be sure I didn't put it in backwards. It's OK.

Is there a way to test the thermo/switch?

How do I check the water pump to be sure it's OK?

[ellpee]

As far as the electrical, you got it, dude. That OEM fusebox has issues -- connector slots tend to push down out of place, equalling poor or no connection. I totally replaced mine with one from Autozone. Your testing of the fuses themselves sounds okay; I just use a 6v flashlight battery, multimeter. If 6v gets through to the other side, fuse is okay (whereas eyeball system can fool you, can look good and still be bad).

As to fan circuit, my understanding is that from A to Z it's as follows: juice from battery --> inline fuse on red wire --> ignition switch --> back to fusebox --> through fuse for fan only --> to thermoswitch on bottom of radiator (((NOT thermostat, two different animals))) --> to fan --> to a ground somewhere. It sounds from your description like you've eliminated almost everything, but it's still possible that thermoswitch isn't coming on at the intended temperature, which I'm told is around 176 fahrenheit. (Or was it 167?) Anyhow, on my 2011 Roketa, which is very much similar to your 2008 Jonway, the temp gauge on the dash has never yet gotten above the midpoint, and the fan kicks in right at the midpoint. If your gauge is getting much higher than that, I'd certainly be looking at that thermoswitch. Alleyoop or JR or other gurus, feel free to chime in if I have any of this wrong. But I learned it all from you!

[tumbleweedt]

Thank you, guys. You've all been such a big help. This is such an amazing resource! I hooked up the wires to the thermo-switch, replaced the small amount of coolant I lost when I checked the thermostat, started it up... AND... EVERYTHING IS WORKING! The fan is cycling on and off just before midpoint on the gauge, and water is circulating well. So I'm thinking I'll apply some Permatex dielectric silicone grease to all connections. Then cover everything up, and GET BACK TO RIDING! Thank you all!

[skyrider]

The temperature sender for the gauge is on the bottom of the radiator.

[tumbleweed]

Isn't the temperature sender for the guage actually on the thermostat housing.  I believe the thermo-switch (that, when it reaches a certain temperature, completes a circuit that turns the fan on or off) is actually the one that is located at the bottom front of the radiator.

[alleyoop]