KymcoForum.com
Scooters - 125 to 300 => People 250 => Topic started by: jprestonian on March 08, 2010, 06:30:24 PM
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Whoo-hoo! I feel some SPRING comin' on.
Two weekends ago, I took a few long rides... that Sunday, I developed an issue: The temperature gauge started swinging wildly from midpoint to pegged "hot." and throttle position, terrain, et al, had no discernible effect on it. The mechanic who was on the ride said not to worry, as long as I didn't smell antifreeze, and I didn't, and haven't. Still, on these warmer days, the gauge reads full-on "HOT!" even though the cooling system has plenty of coolant, and even at this reading, one can put one's hand on any part of the radiator, and leave it indefinitely without being uncomfortable. Bike's running good, MPG is where I would expect... seems fine, other than this needle business.
What are the chances this is just a faulty sensor?
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It kinda sounds like a faulty sensor. Have you looked in the service manual for a way to check the sensor? That would be my first step.
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I would have thought the radiator should be too hot to put your hand on. maybe a blockage or faulty thermostat. Better to check than do damage to the engine.
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I agree w/ sid! Have you tried touching the engine cyl/head? If the t stat is not opening the radiator will stay cool, and the engine will take all the heat. Just to double check. MOST likely a bad sensor tho. I say that cause it is bouncing on you, and not holding. If there is a short, or worn insulater somewhere that ground will throw the needle to fullllll hot also,. You can verify all that w/ a cheap OHM meter. Try the 100 scale at warm. try to get the needle (on the meter) close to center using the diff. scales. Then you can ride a bit, and compare the meter to the gauge. If it is the sender or a short they will both bounce. if it is your gauge only it will bounce. (just paralelle the 2 off the sender) You can then remove the wire from your sender to your gauge, and see if the meter still bounces. that will show faulty wireing if there is no bounce, and a bad sender if there is. Hope I didn't make it too confusing w/ all that bouncing around!~
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Well, just a six-mile trip today had the needle pegged about 90% of the time, so now y'all have got me paranoid that at the very least, the thermostat is stuck shut. No coolant in the water pump's weep hole, so I reckon THAT is good news, at least.
Riddle me this: Why does a vehicle without a heater core even have a thermostat?
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Sorry, I missed the bit about it swinging wildly, is more than likely a short. The thermostat it to keep the engine operating within a desired temperature range, especially in colder climates.
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You can easily pull the t stat, and go for a ride! You can also verify the t stat in a pot of water, and a candy thermometer. It should open between 140-160 I use a candt thermometer because they are super accurate, and 3.99 at WalMart
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Well, just a six-mile trip today had the needle pegged about 90% of the time, so now y'all have got me paranoid that at the very least, the thermostat is stuck shut. No coolant in the water pump's weep hole, so I reckon THAT is good news, at least.
Riddle me this: Why does a vehicle without a heater core even have a thermostat?
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To get the engine to operating temp and to signal the "ELECTRIC" fan to engage when hot...Has the fan kicked in?
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Well, the fan does kick in, yes... but the same sensor that tells the gauge the bike is hot also trips the fan switch.
Given the symptoms so far, I'm still betting it's a bad thermosensor (~$26), but I might as well go ahead and buy a thermostat (~$40!), as that is also somewhat likely, given the age of the bike, I'm guessing. Seems like the right time of year for one to fail, too... coming off many miles of cold weather riding all winter, and then a few warm days... it seems to make sense to me. It seems quite possible that the thermostat may not be opening far enough to allow good flow of coolant, but open enough to not cause a catastrophic failure... just yet.
For instance, I can let the bike run at a standstill, 60F outside, just idling, for 20 minutes, and the gauge never goes above 2/3rds. Take a 2-mile run though @ 70F, and the needle is pegged, and now STAYS pegged.
What ill effects might I expect on this machine if I just remove the thermostat, altogether?
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zombie -- Did not touch the cylinder head, as I would expect it to be quite hot after a few miles even when the cooling system is working perfectly. ;)
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..can it run too cool??
..maybe in colder weather, but in warm weather i think it should be fine to run without a thermostat...
..i've done it in my passenger vehicles from time to time back in th' day...
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The only possible draw back w/out a t stat. is the temp could keep climbing on very hot days. It adds just enough blockage of the coolant to keep it in the radiator long enough to remove the heat. MOST ALL engines will have little/no trouble w/ no t stat, but the marginally designed ones will. Better to remove it for a test run, and get one when you can. I also believe there is a nylon adapter that runs your coolant pump. Might want to make sure the pump is working too.
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All that makes perfect sense to me. I guess my next trip will be to Advance Auto to get a jug of antifreeze, and then pull that bad boy out (and test it; might as well!) for now. It won't get that hot before the replacement arrives, I'm betting.
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I head awhile back that an engine can run too cool. If it runs cooler than the optimum temp it runs less efficiently. This is why truckers have the radiator flaps for the winter time. It will still run, you just may have a slight drop in fuel efficiency.
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I'm less worried about efficiency than I am warping my head. ;) Practical sombitch that I am...!
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Very true! I know what a stickler you are about your fuel efficiency though! Just thought I'd throw that out there. ;)
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True enough. But if I blow the damned thang up, its mileage ain't gonna get any better, for sure. ;)
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The only possible draw back w/out a t stat. is the temp could keep climbing on very hot days. It adds just enough blockage of the coolant to keep it in the radiator long enough to remove the heat. MOST ALL engines will have little/no trouble w/ no t stat, but the marginally designed ones will. Better to remove it for a test run, and get one when you can. I also believe there is a nylon adapter that runs your coolant pump. Might want to make sure the pump is working too.
I head awhile back that an engine can run too cool. If it runs cooler than the optimum temp it runs less efficiently. This is why truckers have the radiator flaps for the winter time. It will still run, you just may have a slight drop in fuel efficiency.
..lesson learned...thermostat 101... ;D
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True enough. But if I blow the damned thang up, its mileage ain't gonna get any better, for sure. ;)
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I did not read the thread carefully.
Does the fan turn on when the engine heat gauge goes into red zone?
Lucky you, I do not have that gauge on my P250S...
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no temp gauge was my first gripe.
:)>>
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Going on the logic that it would be better to have a faulty thermosensor than a thermostat stuck nearly-closed (which is what I now suspect, after getting your valuable feedback), I've got a new thermostat on order. Can't believe what the markup on these puppies is... wow.
I should have taken the old one out, today, but it's managing to stay open enough to keep it from staying pegged all the time. Still no coolant in the weep hole, and the scooter's running fine. I did take a break on my trip today to let it get stone-cold again before doing the other half of my short (10 mile) trip. Plus, the part should be here no later than Tuesday. I'll just try to keep trips very brief, and/or take breaks in the middle of rides like today's.
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Have you checked your coolant level? I have seen where steam being hotter than the coolant itself will bounce the needle as it passes the sensor. Just another thought, as I see you have it under control.
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Well, yes, in a manner of speaking. We replaced the thermostat last Thursday or Friday, and there was an immediate improvement. However, the larger improvement didn't come until Saturday, when I burped a half-pint or more of air out of the cooling system. I think there's still some in there, but not enough to cause the severe overheating I was getting.
Air in a system like this can cause cavitation (http://en.wikipedia.org/wiki/Cavitation), which is very stressful on things like impellers, hence seals and water pumps. So over the course of the next few days, I'll be constantly burping it, and adding coolant.
Damn shame it takes 10 screws to get the front cowl off.
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I was thinking about you 2 nites ago, and your overheat. Good to see you got it. As for the cowl... Run NAKED IN THE STREETS. I would pay to see the blog...
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I was glad i had temp gauge this weekend. My exhaust pipe blew but I was able to fashion a fixed with a muffler wrap and soda can (that failed 300 miles later, replaced with a slightly better patch made of stainless steel strap and hose clamps.)
I kept an eye on the temp gauge the whole weekend. I was able to ride over 700 loud miles by watching my temp gauge.
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Well, yes, in a manner of speaking. We replaced the thermostat last Thursday or Friday, and there was an immediate improvement. However, the larger improvement didn't come until Saturday, when I burped a half-pint or more of air out of the cooling system. I think there's still some in there, but not enough to cause the severe overheating I was getting.
Air in a system like this can cause cavitation (http://en.wikipedia.org/wiki/Cavitation), which is very stressful on things like impellers, hence seals and water pumps. So over the course of the next few days, I'll be constantly burping it, and adding coolant.
Damn shame it takes 10 screws to get the front cowl off.
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Would you care to explain a bit how is the coolant replaced in P250?
Thanks.
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On the People 250 (not S 250, although the concepts are the same), I remove the ten screws that hold the front cowl to the other body panels, unplug the turn indicators, and remove the cowl and set it aside.
I then open the radiator cap, and add coolant, if there is not coolant all the way to the top of the cap. Then, I start the engine. As the engine warms, and the thermostat opens, coolant circulates through the entire system, and air bubbles will come up into the radiator, and eventually out the filler cap. This causes the fluid level to drop, so I again add coolant.
One can only do this so long before the whole system gets so hot as to splash out coolant, and not just air. At that point, I shut off the engine, and let it cool, and repeat the process.
I imagine if you wanted to drain all the coolant, disconnecting the big hose at the bottom right that connects to the impeller, and very briefly running the engine (w/radiator cap open) would quickly drain most of it.
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On the People 250 (not S 250, although the concepts are the same), I remove the ten screws that hold the front cowl to the other body panels, unplug the turn indicators, and remove the cowl and set it aside.
I then open the radiator cap, and add coolant, if there is not coolant all the way to the top of the cap. Then, I start the engine. As the engine warms, and the thermostat opens, coolant circulates through the entire system, and air bubbles will come up into the radiator, and eventually out the filler cap. This causes the fluid level to drop, so I again add coolant.
One can only do this so long before the whole system gets so hot as to splash out coolant, and not just air. At that point, I shut off the engine, and let it cool, and repeat the process.
I imagine if you wanted to drain all the coolant, disconnecting the big hose at the bottom right that connects to the impeller, and very briefly running the engine (w/radiator cap open) would quickly drain most of it.
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Thanks.
I was wondering, is there some other way to drain the fluid out than disconnecting the hose? It sounds kind of "crude".
The cars usually have some kind of screw, screws or several drain plugs.