cooling system question '97 VLX 600

[Raven080510]

Alright, fellow gearheads. Need some advice on the cooling system on my scoot.

First off, as described in the sg. below, it's a 1997 VLX VT600c, with a wopping 49k+/- miles on it and steadily rolling along daily. I'm curious if there is an issue with my thermostat. I keep a regular check (once weekly-never having to adding much coolant at ALL) on my coolant level, and lately I've noticed that when I park the bike after my commute (to and fro), my reserve tank pukes coolant. It's not a large amount- just maybe 3 or 4 ounces at most. I may have overfilled my reserve tank, but one would think that any extra would have came out when it happened the first time. Anyway, I pulled the radiator cap, started the bike and let it warm up. I looked for any sign of circulation, and it was evident that it was in fact circulating, but to what degree, I'm not sure. I read in previous posts, that the temp light is supposed to come on for at least 2 secs or so after turning on the ignition. Not happening in my case and as a matter of fact has never came on. Also, I very rarely notice my fan spinning.

The previous owner claimed that it never got hot enough to come on besides about a 50 or so mile trip they took over the summer. He said the fan came on then. Anyway, my main concern is overheating my scoot, and the small amount of puking after I park the bike is a bit of a concern. (water boils at 212 degrees, so my engine has to be getting at least that hot.)

Could it just be air in the system pushing the coolant out? (I did bleed the radiator after each coolant top-off.)

Is my thermostat not opening fully or opening too late? (weak spring?)

Anyone with any experience in the area, shoot me some suggestions.

Thanks!!

[knucklebuster69]

It might be a good idea to put a new one in just for good measure. While it is true that water boils at 212 degrees, coolant should have a higher boiling piont. Like 230 degrees or more. Plus, liquid under pressure the boiling point increases even more. You may also have a bad pressure cap. I would replace it.

[gmck]

my 94 vlx uses the fan a lot. after I've been driving a few miles to get fully warmed up it comes on at most lights. I had my fan switch fail and have replaced it. Check that the fan works by taking the wire off the fan switch at the bottom of the radiator and touching it to a ground with the ignition turned on.The fan should run. I tested my switch by taking it out and using my meter holding it in boiling water.

[jpr1968]

Check your radiator cap. One of your local auto parts stores should have a tester to check it's pressure relief poin.

[CavemanBen]

i was concerned that my fan thermostat wasnt kicking in, so i took the ground wire from it and spliced it to a toggle switch (which i grounded to the frame. now if im sitting in traffic i can reach over to the front skirt and flip the switch to override the t-stat. its paralleled so the t-stat will still turn it on (if it works)

[CavemanBen]

as far as replacing the main t-stat, its like $45 and easy to do, so you might as well do it to be safe. remember to replace the o-ring for it too

[Raven080510]

I like the looks of that, Caveman. I keep a toggle switch along with a pair of wire strippers, a little wire, and connectors in my saddlebags just in case, lol. But tbh, I'm leaning more toward the fact that I've just not gotten it hot enough to come on. I baby this thing (well, half the time) with the amount of miles it has on the clock. I did, however, check the fan today while at work, grounding it out at the frame, and it came right on. The thermosensor (correct me if I'm wrong) that my model has that controls the fan operation may very well be bad, since it powers the temp led as well I believe and it never comes one when I turn the bike on for the few seconds it is supposed to. I may pull the thermosensor one day this week at work, and check it out with my multimeter like you suggested. Or I could just check for power coming from the thermosensor to the led in the speedo when I cut the switch on. If it shows power, my led is bad. If it doesn't then the thermosensor is bad. Wouldn't that be correct? I may also soon go ahead and pull that tank off (thinking of adding some color along with the black anyway, I'm never satisfied, lol. doesn't help to be a painter/bodyman either lol) and pull the filler neck and check out the thermostat on the hotplate with a bowl of water. Honestly, there may not even be an issue. I'm such a worry wort and very meticulous with my personal things, especially with mechanics. I'd like to add that I didn't have any coolant drainage this morning or this evening when I parked the bike. I'm thinking I may have just over-filled the reserve after all. However, the issue is still there of weather or not my thermosensor is bad considering I have never seen my fan running, and my temp light doesn't illuminate upon 'switch on' per the service manual.

[CavemanBen]

well i know my over-temp light comes on with the key (with out turning the engine over), but on my vlx the engine was so quite that it was obvious when the fan kicked on while i was stopped. and even in cold weather that fan will kick on after 30 minutes of riding. im under the impresion that these fan temp sensors on the radiator dont normally fail, so maybe its just a bad electrical connection somewhere. i cut in that toggle on my aero after replacing the main thermostat (bike was over heating) but before testing it properly because the bike was not legally on the road yet. turns out that the fan t-stat works just fine, but my switch is wired so the t-stat will ALWAYS turn on the fan, but on a hot day in traffic i can force it on to be safe.

[justinmahn]

I like that idea. It would give me peace of mind as well, knowing the fan still worked.

[kacealraid]

Should the temperature light on your speedometer come on when you turn on the bike?(Before cranking) Mine never does.