So, this morning, I reduced the coolant level in the expansion tank to the low mark, fitted a new hose clamp to replace the missing one on the small pipe from the side of the expansion tank, ran the bike up to temp on tick over, with a couple of throttle blips thrown in Cooling fan kicks in and out at 80 to 82°c, took just over 9 minutes on tickover for fan to kick in at approx 82/83°c, fan off at around 11 minutes, back at 80°c 20 minutes, noticeable bubbling in expansion tank, no leaks 21 minutes 30 seconds, bubbling and leaking from between expansion tank and the filler neck Replaced the expansion tank cap with the one from my 916, coolant still hot, within a few minutes, bubbling and leaking out again
Yup, that 80/82 degrees C window is right in the middle of the normal operating temps. Which means the fan would be constantly on/off while riding, even in normal non-summer outside temps… Surprising.
Another cracked/split expansion tank? It may be a new one but as the years go on, they’ll last even less longer as they get weaker over time.
Brand new from Ducati, had to be ordered in Took the filler neck off again, cleaned out the inner part where the cap seal sits, checked the O ring, to make sure I didn't pinch it when installing it Now going to get cleaned up, and take it for a ride, to see what happens when ridden, as opposed to just sitting there idling
Update... After a spirited ride, mainly along a nice wide, single carriageway bypass road, did approx 20 miles up and down the same road, at fast speeds, nothing in front, the temp gauge hovered around 40°c for the first few miles, rose to around 65/70°c when slowing down for the roundabout, then dropped to around 45°c when I picked up the pace again, when stopped at lights, it rose to around 80°c, then dropped again when I got moving again The highest it reached was around 90°c during a prolonged stop at lights whilst waiting to turn right, then dropped to around 70° after making the turn Kept looking down at the filler neck, no sign of coolant loss Will check the level when the bike has cooled down Not sure if the temp gauge should fluctuate as much as that
Sounds like your temp gauge is under reading. 40deg while riding is very low. Can’t remember what temp my 748 and 916 ran at but I seem to recall the gauge was in the middle - whatever that reading is.
Yup. What yer man said. About 180F or 80c would be my experience of normal on these bikes. Possibly a bit lower on the open road but not by much.
Yeah, your temp gauge looks toast to me. A « spirited » ride at 45 degrees would have destroyed your engine…
My interpretation of spirited meant fast, not revving it to redline, if that makes any difference? Probably not though
The gauge is easily checked by grounding the wire. It should then go to max temperature. Fluctuation in temperature the way you describe, if they're not a faulty gauge, would point to a stuck open thermostat. The fan switch isn't linked to the gauge which would also point to the gauge or, more likely, the thermistor that the gauge uses. Here is a link for the one I use on mine. https://www.ebay.co.uk/itm/36419262...amhx4rcrvk&var=&widget_ver=artemis&media=COPY
So, if I remove the wire on top of the thermistor (from your link), and ground it, if the gauge goes to max, the gauge is fine, and the thermistor is the cause? Just making sure that I understood your post correctly
If you ground that wire the gauge has to go to max yes. The erratic gauge could also be a bad connection to the sensor or it could be the sensor. Although the sensor is more likely to completely fail than to give erratic reading. You can check the sensor by measuring resistance at different temperatures. I think it's about 1KOhm at room temperature but don't quote me on that. Anyway, the resistance should decrease when temperature increases. I
My 916 had exactly the same indications on the temp guage as yours. It had been running very very rich which was eventually sorted with a new Air temp sensor ( it was the last thing I changed due to misinformation on the internet) I had changed all the temp sensors and thermostat. It ran beautifully but the temp guage still read very low. I fitted a different guage but still the same. The last thing I needed to do was change the alternator casing I sourced a secondhand one which had had the alternator wiring upgraded its whole length. I fitted that refilled the coolant for the umpteenth time and boom the side effect was the temp guage started working properly This of course doesn't help you as I have no idea why this should cause the guage to work
Could this be a possible cause for the temp gauge fluctuation? Bit of corrosion on the terminal for the thermistor Just got to check my toolbox, see if I have any new terminal ends, so I can replace it
