Zongshen RX3: Engine Cooling System

[Biker_Andy]

The smaller the engine the greater the effect when the fans kick in / out or when the thermostat opens / closes. A 250cc engine doesn't make all that much heat so external forces will influence it very quickly.

Combine that with an imprecise digital gauge (only 5 bars to indicate the relative heat) and it may look like its bouncing around at certain times. Imagine if a heat value of 1 = 1 bar on the display & 5 = 5 bars heat, if the value is fluctuating between 2.999 and 3.001 the display will be bouncing between 2 and 3 bars even though the change in heat would be unnoticeable with an old school analog gauge. This is a common problem with digital displays.

[Citroenjunkie]

I appreciate the responses. I hadn't thought through the digital gauge thing. I suppose that explains the rather pessimistic fuel gauge too.

[Jay In Milpitas]

Originally Posted by Citroenjunkie

I appreciate the responses. I hadn't thought through the digital gauge thing. I suppose that explains the rather pessimistic fuel gauge too.

Courtesy of our fellow RX3 rider in Argentina, peperino, the fuel gauge solution is here: http://www.chinariders.net/showpost....27&postcount=1

[jogirob]

Originally Posted by rjmorel

Mine does that also on hot rides . I can watch the temp gage go from 3-4 bars going up hills and come back down when going down other side of hill. For piece of mind though remove radiator cap when it's cooled off and see if the coolant level is up to top. It took several refills to get mine topped off when new because of air trapped in the system. rj

I barely noticed at mile 600ish that my coolant overflow bottle is about an inch below the Low mark when cold, and after returning from a 15 minute ride. I guess this means I shouldn't be too worried about coolant loss and just top it off then? Should I top off the radiator or should I add enough antifreeze to reach the L mark?

[SpudRider]

Originally Posted by jogirob

I barely noticed at mile 600ish that my coolant overflow bottle is about an inch below the Low mark when cold, and after returning from a 15 minute ride. I guess this means I shouldn't be too worried about coolant loss and just top it off then? Should I top off the radiator or should I add enough antifreeze to reach the L mark?

Yes, open the radiator cap and fill the radiator to the top with coolant. You can also tilt the bike from side to side, and add more coolant if the level drops.

The easiest way to top off the overflow bottle is to remove the overflow hose from the radiator, insert a small funnel in the hose, and pour coolant into the funnel.

[mckayprod]

Anyone have a quick way to test the fans? It's over 100 around here, and confirming their operation would make me happy. My BMW overheated once when the fan siezed up, and that was a drag.

[pyoungbl]

Originally Posted by mckayprod

Anyone have a quick way to test the fans? It's over 100 around here, and confirming their operation would make me happy. My BMW overheated once when the fan siezed up, and that was a drag.

You can insure that the fan itself is not hitting the radiator by simply spinning the blade with your finger. Other than that you need to test the temp sensor by immersing it in boiling water...not the simple test you are looking for. These engines tend to be over cooled but if you let the engine idle for a while (no air flow) you should be able to get the fans to kick in. I have only had my fans come on in an extremely hot situation.

Peter Y.

[Jay In Milpitas]

Originally Posted by mckayprod

Anyone have a quick way to test the fans? It's over 100 around here, and confirming their operation would make me happy. My BMW overheated once when the fan siezed up, and that was a drag.

Yeah Buddy, 108 here next to San Jose yesterday and possibly a bit more today.

Two testy bits.

1. Unplug the connector from the bottom of the left radiator and with ignition turned to On, jump the two connectors in the wiring harness. Fans should do the whirly-gig jug.

2. Just start the engine and let it idle while you sit idly by and watch the temperature hinting bit on the video display. When the fourth bar comes on or shortly thereafter (facetious big word thrown in there) the fans should both start spinulizing.

Number 1 will not test the temperature switch function, just the fan operation.
Good luck.

[mckayprod]

Thanks for the tips. With 110 in the forecast I want to be sure. I haven't hit the fourth bar yet, in 11k miles.

[Jay In Milpitas]

Originally Posted by mckayprod

Thanks for the tips. With 110 in the forecast I want to be sure. I haven't hit the fourth bar yet, in 11k miles.

I've had it go 4 bars a few times, always in high temp weather. Some of the times were sitting in traffic waiting on a long red light to change, and a few times were just after exiting the freeway after high speed riding and coming to a stop at the signal at the end of the exit, engine still hot from the run but idling at the light so very little circulation.

Also on hot days, arriving home and leaving the engine running in the driveway while I go open the garage door, remove helmet & gloves, go back to bike to ride it in and just about then the fans kick in.