Desperate for cooling system help

[Trancebear]

Need some help guys and gals. My new scooter is overheating after riding for 20-25 minutes. My gauge goes from 1-5 bars (digital).

I burped the cooling system and then I run it at idle in the garage. It gets hot at the engine pretty quickly but takes forever to get hot at the radiator. The gauge goes up to 4 bars and finally the cooling fan goes on and keeps the engine cool. On the road the same thing happens but the gauge does not go down and shoots to 5 on the gauge.

I have replaced the thermostat, temp sensor, water pump and fan motor. Could this be a bad thermostat? It seems to not be circulating the coolant. I purchased a stock thermostat from the dealer so I know the temp spec is correct. This is so frustrating having my new scooter run so good and I cannot ride it.

[jmkjr72]

pull the tstat and put it in a pan of water with a thermometer in it and put it on the stove and boil it and watch for it to open up

did you flush the rad too i have also seen stuff like that happen when the hoses are reversed on the water pump

[Trancebear]

Thanks for responding, system flushed well, no obstructions. Hoses are where they should be. Gonna test thermostat tomorrow, just a PITA to refill coolant and burp the system.

[Rebel]

Is this a new thermostat doing this?

I've never owned a water cooled bike but in cars I have seen thermostats mysteriously just go bad once air has hit them for some reason.

[theswede]

One thing you could try is to simply remove the thermostat altogether, and run without it. This is a common trick to do on marine engines if they start showing signs of overheating, to get you back to the harbor.
Removing the thermostat will not damage anything, the engine will simply be running colder and take much longer to reach working temperature.
It will provide you with a definite answer if the thermostat is the culprit or not. And the lessened resistance in the cooling circuit may help removing any air bubbles that is blocking the system.

/Otto

[Trancebear]

Dec 28, 2011 8:42:39 GMT -5 theswede said:

One thing you could try is to simply remove the thermostat altogether, and run without it. This is a common trick to do on marine engines if they start showing signs of overheating, to get you back to the harbor.
Removing the thermostat will not damage anything, the engine will simply be running colder and take much longer to reach working temperature.
It will provide you with a definite answer if the thermostat is the culprit or not. And the lessened resistance in the cooling circuit may help removing any air bubbles that is blocking the system.

/Otto

I was thinking about this, I will try it if no damage can come of this. My scooter is ECU controlled so I was hesitant.

[Trancebear]

Just took out the thermostat, it was stuck open. I left it out this time. Re-filled the system with coolant mix and started the scooter back up. I figured the coolant would just get sucked into the radiator and I would have to add more seeing there is no thermostat installed. The coolant remained still and did not go down. I let the engine warm up which it did rather quickly. It should of taken longer without a stat. Drained coolant again after it cooled off. Took the water pump housing off and unplugged the spark plug to just turn the engine over to see if the water pump impeller turned and it did. There must be a clog somewhere but I have flushed the system 11 times now. Distilled water is not cheap.

See pics to check if everything looks good with the water pump. Am I missing something?

[theswede]

Is the thermostat perhaps part of the pump housing? It may be that when it is stuck open (or when removed), the pump is not working as it should.

My experience with liquid cooled engines is limited to marine diesels, but it is pretty common to get air bubbles in those systems, blocking them. The key to fix it is to let the engine idle, and loosen the cooling lines one by one (starting from the pressure side of the pump) and check that there is coolant flow. No need to remove the hoses, just loosen the clips enough that you get a leak.
Quite often you get some air instead of coolant, or coolant + bubbles. Let it flow until all air is removed, then tighten the clip and continue to the next point in the chain. Repeat this until you are back at the pump.

Also, if you have an A/C unit at home you can use the condenser water that comes out of it to refill the system. It is 100% distilled water.

[Trancebear]

Thanks for the info Swede!

I went as far as to replace all the sensors..lol. I was really desperate. I FINALLY fixed it. First thing, every time I installed a new thermostat it would ruin them. Very weird. So I ditched my 3rd ruined one and I am running without a stat right now. The main problem that caused the coolant not to flow correct was a hidden passage underneath the engine that would flow good when cold but the sludge would block the passage when hot. Got it all cleaned out and she is running nice, no overheating. Took me 4 hours to burp the damn thing and I am loving my awesome scooter. Got it up to 80mph on the HWY today and she stood steady at 2 bars on the temp gauge. I am running Evans water-less powersports coolant, $45 a gallon and worth every penny. Check it out here:

www.evanscooling.com/products/coolants/npg-plus-c/

I should have the factory LED turn signals by Saturday just in time for a charity New Years Day run to the mountains. Also I should have my Shark stereo system installed.

[jmkjr72]

do keep an eye on your temps
some of the things with small rads the tstat pulls double duty
it opens up to let water flow but it also restricts it some too

i had a car that over heated big time the tstat stuck closed on the side of the road
pulled the tstat put some water in as it was all i had
and every 15 min i was haveing to pull over and let it cool off
went 100 miles before i found anyplace and that was a truck stop talked to one of the wrenches there and he busted out the part of the tstat that moves and said put here back in and i was good till i was able to get home and get a new tstat

[Trancebear]

This situation is only temporary, looking for a better quality stat as we speak. The stock stat is a 76c or 165-170 degrees. I have the option to go with a 190 degree one. It looks beefier but will fit. What do you think?

[Rebel]

I think you should put the thermostat back in that is stuck in the open position. Running in the winter may not be a problem but you may find that in warmer times of the year the coolant will flow to fast through the radiator to cool it down. Just keep that in mind.

[Trancebear]

The thermostat issue is only temporary, new one was ordered today.

[theswede]

Glad to learn that you found the issue! Hope it works out with the new thermostat.

[mariaseiler]

Der kostenlose Demomodus ist eine großartige Möglichkeit, sich mit den Spielen vertraut zu machen. Wählen Sie selbst die Spiele aus, die in Geist und Thema näher beieinander liegen. Das mathematische Modell diese WebSeite eines Freispiels ist identisch mit einem Geldspiel. Daher wird Spielprofis empfohlen, zuerst den Spielautomaten im "Free" -Modus zu testen, ihre Gewinnstrategie zu entwickeln, die Spielmechanik zu erlernen und erst dann das Spiel um echtes Geld zu starten.