Does radiator fan and temp gauge use same sensor?

[FZyLarry]

My FZ is a little over 3 years old now (an '06) and has just under 20K on the odometer. A couple weeks back I was looking at campsites in a campground - lots of stops & idling in neutral while I noted good looking campsites. As I was finishing up I noticed that my temp gauge was showing hot - something that it had never done before. However, as soon as I rode a few yards the temperature came back down to normal and as the day went on I never saw any readings above normal - 3 bars. A few days later, again in a stop & go scenario I noticed the same thing happen. Once again, getting moving made the temp drop and I never really did notice if the fan had been on or not.

Since then I have been checking my fan and it never is coming on (but it has never got above 3 bars either). I went through the diagnostics in the service manual and everything has checked out OK except the temperature sensor. Of course, this is the most difficult thing to get to and I would need to drain my coolant to check it.

Before I do this I have one burning question - is the temp sensor on the back of the cylinders used for both the fan and the engine temp I see on my dash? If so, it must be working since it goes from cold to warm and in a couple of cases hot. I don't want to go to the effort of pulling the sensor out if it isn't broke.

Any suggestions?
Thanks!

 

[Motogiro]

Don't know but I will look at a service manual and see if i can find the circuit.

Make sure you don't have a pebble stuck between the radiator and the fan, jamming it from moving. It happens on the FZ-6. Somehow the tire will fling a little rock and it wedges itself stopping rotation.

I don't know when the fan is supposed to come on or how many bars should be showing.

I'll try to get back to this thread with an answer....

 

[FZyLarry]

Thanks for the suggestion but the fan turns freely. As a matter of fact I did a test not in the manual. I removed the fan motor relay and jumped across the leads that would be made if the relay kicked in - the fan ran perfectly. I also followed the test instructions for the relay and it appears to be working perfectly.

 

[champion221elite]

My fan turns on when the temp gauge reads 212 degrees fahrenheit. The sensor, gauge and fan must be connected in some way.

 

[Zack]

I noticed about same on my FZ. Last week I spent in Sarasota, hot weather. Regular ride temp is about 185-195 F but as soon as I stop at traffic light aft few seconds I see temp rising. Quickly it gets to 205-210 range and higher to 220, fan turns on but there is no much relief. I have impression that engine would overheat regardless.
When I shut down many times fan is still on for some time. I don't think a fan is big enough

 

[Motogiro]

The fan is ECU controlled. The ECU gets it's signal from a varistor type sensor and then the ECU turns on the fan relay. On my R1 the fan comes on at 221 deg.F. It might not be getting hot enough to come on. Check your fuse, a 20 ampere, I'm pretty suer, in the right pod. There are two 20 amp fuses, one is the headlamp the other the fan.

Hope this helps..

 

[FZyLarry]

I checked the fuse first thing, it's good.

How do I know the temp in degrees? I read through my owners manual and I don't see a way to get any engine temp except the bars.

 

[Motogiro]

I checked the fuse first thing, it's good.

How do I know the temp in degrees? I read through my owners manual and I don't see a way to get any engine temp except the bars.

The 06 doesn't read in degrees. I think that's 07 and later.....I don't think the fan comes on below 4 bars....

 

[philosopheriam]

When is the last time you flushed your coolant?

 

[FZyLarry]

When is the last time you flushed your coolant?

It is past due but since it runs so cool I never really worried about it. I guess that would be a logical step and just plain old good maintenance. I would hate to do the flush & new coolant and then find the sensor still needed to be replaced. That's why I'm asking about the relationship with the gauge on the dash panel. If it uses the same sensor, then the sensor must be good because the gauge is working fine.

The devil is in the details...

 

[philosopheriam]

I'm a mechanic, and I'm never in favor of just changing parts for giggles...

HOWEVER

I don't believe that the temp sender is very expensive, so, I would go ahead and change it and then flush the coolant at the same time. When you change the sender, make sure to check the wires in the back of the plug and check that the metal contacts in the female end of the socket are making good contact with the male ends on the sender.

As for flushing, here's what I find works best:

1. Pull the radiator cap
2. Put a drain pain underneath the water pump drain plug
3. Drain the coolant - drain/clean the resevoir, too
4. Reinstall the drain plug
5. Fill the system with clean water and replace the cap
6. Run the bike until it reaches operating temp and the fan turns on
7. Shut the bike off
8. Remove the cap/drain plug and drain the water from the system
9. Pour some coolant in the system while the drain plug is removed - this will push the remaining water out of the system.
9. Reinstall the drain plug, fill the system with coolant (dont forget the resevoir), put the cap on, and run the bike.

My bike ran 5 degress cooler after a full flush and refill

Hope this helps!

 

[FZyLarry]

Any thoughts on what coolant to use? I know it has to be for aluminum but is automotive coolant OK?

 

[04fizzer]

Your fan should come on at 4 bars, and go back off at 3. If you're not getting above 3 bars, then it wouldn't come on, and all is normal.

 

[philosopheriam]

Any thoughts on what coolant to use? I know it has to be for aluminum but is automotive coolant OK?

Pre-mixed ethylene gyycol - i.e., the green stuff

The pre-mixed stuff is proportioned perfectly and the water is de-mineralized. It works great and save you the hassle of mixing stuff....

 

[Kriswithak]

Comes on at 100 C for me (don't use farenwatever here) and as soon as it comes on the temperature stabilises.
Funny thing about motorcycles is they are meant to be moving, and not moving but running causes heat, which has a hard time dissapating particularly if its hot weather.
If your fan turns on when it gets hot your fine, if it turns freely (easy to check by hand - then your probably also fine)

 

[TownsendsFJR1300]

If you let the bike sit and get hot, to 4 bars, and the fan doesn't come on, you know the switch is bad or you have a bad connection between the switch and harness. The sensor you describe is the only sensor..

As for the anti-freeze, I use the pre-mixed Prestone (50/50). It should be changed every 2 years. It will make a difference on how fast the bike heats up and how fast it cools down... I noticed a significant difference especially in my FJR...