Modern Vespa

My dealer did a thorough checkout of my GTS 250 and worked directly with Vespa, and concluded that my scooter was running within spec.

But I swear that for about the first 3 years of ownership the fan would hardly every kick on in any weather except if was really hot and humid and I did a lot of idling.

Now it kicks on intermittently as soon as it gets to normal operating temperature. I find this annoying and needless. Sometimes it runs on a cool morning while I'm moving and the air from moving has to be more than what the fan can push.

I believe this to be a design problem because the sensor for turning the fan on and off is attached to the engine (near the thermostat) instead of on one of the radiators.

Anybody have thoughts on how to solve this? Thanks.

I believe there are two temperature sensors: one at the engine (as you mention) and one behind the glove box, near the fan. If I'm not mistaken, the fan is controlled by the sensor behind the glovebox.

I don't believe this is caused by a design flaw. If it were a placement issue, as you suggest, then the fact that your bike operated correctly for three years would be at odds with that theory.

Is the correct coolant installed? Some coolants will gel up and the radiator won't cool as designed. That would cause overheating. Maybe a good flush and new coolant would help.

Coolant has been flushed and replaced (with correct) coolant; but this was done after it started misbehaving. This did not change the behavior at all. Also, the thermostat and sensor were replaced per chance one of those was the cause. No change there either.

The problem originated just before my stator was replaced, but improved (but not corrected) after the stator was replaced.

It makes sense that the second sensor mentioned would be at fault, but the dealer said there was no such thing. Any info on that I could share with my dealer would be helpful. To me it seems that the second sensor is missing, and that is what is meant by a design flaw.

This thread may help:
GTS cooling fan keeps kicking on.

It ended up being a bad temp sensor together with the thermostat failing. Had them both replaced and problem solved

Both the temp sensor and thermostat had been replaced. Also, the relay was switched out. Behavior had not changed for any of these changes. Read attached link; not sure if there is a short, but doubt it because Dealer says fan kicks on as temp increases according to spec. Antifreeze was replaced and system bled. It still seems like a design problem to me as the temp sensor should really be on the radiator not the engine; or if there is a sensor on the radiator, that is in need of replacement; but again the Dealer says there is no second sensor near the radiator.

My fan never comes on. Some times I wonder if it is defective. The temperature gauge needle is always in the middle so I guess I am ok.
tdi

That is the way mine used to be and wish it still was.

So why would something with a design flaw related to placement work flawlessly for three years and then stop working? The placement hasn't changed...

I wonder if one of your coolant lines is kinked- or the coolant flow is otherwise obstructed (but I stress it's just a guess on my part).

The design flaw theory would be based on the fact that the Dealer said everything was to spec, but the fan still turns on more than it used to; but I see the point. I wonder if when the stator went bad it also burned out another part? But not sure what that would be.

As far as kinks and restrictions, I doubt that is a problem because it never overheats or even comes close.

Checked the function of the water pump?
I've seen automotive pumps with vanes unknowingly sheared off and no one would be the wiser.
Can you see the coolant circulating?

Try another mechanic?
Sometimes we all have tunnel vision and can't see our way to a new line of thinking once we're committed.

I had the same problem and was told nothing was wrong, so I purchased
a second fan from villagephoto MVer and had Massimo install it for me and now
the problem has been solved. 8) See the photos below,

I had the dealer check the water pump, they said it was fine, as is circulation.

Tried another Vespa dealer, although it was further away and they recommended working with my original dealer. So that was a dead end at least for now.

The fan replacement... that may be something, especially if there is a built in sensor on those. Let me investigate that thought... and thanks for pictures and product names.

There isn't. They're controlled by a relay.

Now that I think about it, my fan came on a bunch during the first summer of ownership. Not as much second and now third summer. With the exception of this summer, it is just as hot... I wouldn't sweat it.

So if the new fan does not have its own sensor, I'm not sure replacing it will have much effect on it turning on and off. Also, what I am hearing is that turning on and off can be quite inconsistent from scooter to scooter, from year to year. I am back to thinking it is a design problem. The sensor should be on the radiator, not on the engine. I'll see what my dealer thinks about this.

Just so I know I'm following your reasoning:
1/ You had no issues for 3 years
2/ Now you have issues so it's clearly a design fault, even though you had no issues during the prior 3 years with the same design.

3) fan behavior is inconsistent from year to year for me and others.

Talked to my dealer on Saturday. He recommended I send a note directly to Vespa. So I did. Waiting for response.

The temperature of the coolant in the engine is the critical factor. The radiator coolant temp does not matter as long as the engine stays within limits. The fan control will have an "on" temp, like 105c and then an "off" temp like 100c (these are just gueses). Check to see that the fan is operating within the proper limits. That is all that should matter.

On - 108C
Off - 105C

IIRC

Understood about the temperature. That is what seems to be within spec on my GTS. My assertion is that by moving the sensor for the fan closer to the radiator, it will reduce the needless on/off cycles, by allowing it a chance to cool off a bit before turning the fan on.

According to the dealer who together with PIAGGIO looked into my GTS FAN that was constantly on, in spite of the sensor having been replaced, they replaced the battery for the first time after 21,000 miles and THAT resolved the problem, or so I was told. I will pick up the GTS tomorrow and see.

I installed a switch so that the fan can be disabled whenever I want. Even on a very hot humid day the fan seems to have little cooling benefit.

That seems dangerous to me. Maybe you said but I missed it; What does your dash temperature gauge read? I know that my pickup has two temperature sendeing units one for the computer and one for the gauge.

I'll never understand why everybody is so obsessed with the cooling fan coming on.

This happens in your car all the time (for those of us with cars and electric fans on the radiator), and that's never questioned (because you can't hear it*).

I can understand the obsession if a) it is on constantly, or b) your scoot overheats, but otherwise, why worry? If it wasn't supposed to come on, trust me, Piaggio wouldn't spend the money to put it there.

At the end of the day, it's just a fan blowing on the radiator.

*Actually, that's not 100% accurate, because occasionally, mine will come on after i have turned off, exited and locked the car.

I checked the service manual and there are two temprature sensors. One is variable with tempature, mounted on the engine that controls the gauge and the fuel injection, cold start etc.. The other is near the fan and is simply an on off switch for the fan. I bet that sensor is not working right.

I had already replaced the sensor specifically for the the the fan and that did not resolve anything. As far as obsession goes, the fan kicking on and off annoys me. The fan on a car us under the hood so it is not so noticable. Although I don't know for sure, cars may also have a different design where the sensor is closer to the radiator rather than the engine. That is what I really think is need on these Vespas. Without the added switch, my fan could kick on, on a cool day going down the highway. This proves to me a flawed design. Even on hot humid days when I turn the fan off, the engine stays at normal temperature on the guage. If I should get stopped in traffic on one of these hot humid days I will disengage the swith as a safegard. I am happy with it.