Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > 999 / 749 > Rate of temp increase...Potential Cooling Problem???

[galaxy]

Just got my bike back from the shop for a bad radiator cap. It was overflowing the overflow tank and running out all over the ground. Shop said it was the cap and replaced it. Well, when this was happening, I told the guys it also warmed up EXTREMELY fast. Never overheated or got above 102, but it get's there in a hurry. I guess we all assumed the two problems were related. But, it's still warming up too fast, and it never used to do that. Here's a better description...

Going down the road the temp stays right around 68. Never seen run any colder than that. But, as soon as you come to a stop or in slow traffic, the temp skyrockets to 99+ to the point the fans are coming on. Once the fans kick on the temp comes back down a couple and it continues that cycle until you hit freeway speeds again and the temp drops back down in the 71 range. As before, it never overheats or gets above 102, but I just never remember it warming up a that rate. Even back in the summer traffic it would take several minutes to creep up to the point the fans would kick on. Is there something about the outside air temp that makes it act this way?? Any ideas of another potential underlying problem??

My next thought was possible thermostat stuck closed. Even with the thermostat stuck closed, there is still some bypass/coolant flow through the system. This combined with the cold outside air temps, may be just enough to keep it from overheating but causing the current symptoms. What do you guys think? Is there an easy way to tell if a thermostat is stuck witout removing it?

[Davieravie]

Put a Ohm meter across the pins or sockets. Measure the resistance of the thermostat. Should give you a clue. I dont know the electrical circuit if its open when cold or shut when cold. Hopefully someone should be along soon. Is there any wiring diagrams out there for the bikes circuitry??? Should be a doddle if there are. If I could have a look, shouldn't be much of a problem.

[galaxy]

Ummm, the thermostat is a mechanical device in the cooling system...right?? Simply works off water temp.

[KeefyB]

Originally posted by galaxy
Going down the road the temp stays right around 68. Never seen run any colder than that. But, as soon as you come to a stop or in slow traffic, the temp skyrockets to 99+ to the point the fans are coming on. Once the fans kick on the temp comes back down a couple and it continues that cycle until you hit freeway speeds again and the temp drops back down in the 71 range. As before, it never overheats or gets above 102, but I just never remember it warming up a that rate. Even back in the summer traffic it would take several minutes to creep up to the point the fans would kick on. Is there something about the outside air temp that makes it act this way?? Any ideas of another potential underlying problem??

What was the ambient air temperature at the time?
What speeds were you doing?
On the freeway,were you following traffic or out on your own?

[BIG-G]

If you have lost coolant has this been topped up using only water?

[galaxy]

Ambient air temp is around 17 or under.
Freeway speeds...50mph or better.
Following traffic or not...doesn't matter.
Yes, topped off with only water. Loss was not that substantial though. Definately not a big deal.

[galaxy]

Ambient temp 17 or less.
Freeway speeds...55 mph or greater. Doesn't matter.
Traffic or not made any difference.
Yes, topped off with just water but the loss was not that much.