Im currently trying to diagnose my fathers Daytona. He's had it for about a year and up till now its been great. However, this is what I'm battling at the moment. Its an '04 955i, about 15k miles, factory header with an empty can (no baffles), and a "massive 3" tune. the coolant temps have been going all over the place on the factory digital gauge. After it gets over about 150 degrees, the temps will jump around wildy while the bike is moving, but will remain relatively steady while idling (still abnormal but not jumping from say 180-215 and back). he said that after leaving a stop light yesterday evening that the gauge jumped into the 230's and then staggered back down erratically, I wanted to make sure his fan was coming on at the correct temp, so i let the bike idle until it warmed up. the fan came on when the gauge reported 217 degrees, and the temps started to drop. i like it do the cycle once or twice until i noticed the gauge was being erratic like previously stated. so i shut it off, at which point the coolant boils over out of the overflow bottle. The coolant temp is erratic even on a scan tool, so the computer is reporting the erratic temp and its not the gauge cluster. I drained the coolant, flushed it with a chemical, and refilled with distilled water and "water wetter" While poking around on the bike i noticed that one of the bulk electrical connectors behind the fairing on the right side (clutch side) of the bike was very warm and one wire in particular was too hot to hold on to. White wire. Are these two issues related? Im thinking the temp issue is probably a bad or calcified temp sensor but excess heat in the wiring makes me nervous that the problem goes further than just a bad sensor. any help is appreciated, sorry for the long read. Thanks!
thats on my list of possibilities but doesn't explain 30 degree temp changes in seconds. Does anyone have a part number for a T-stat that isn't the ridiculous $55 triumph unit?
One simple check is to take the t/stat out altogether and see what effect it has. I'm not saying leave it out for good, but it will prove if that is part of the problem. 30 degree change in seconds has got to be a faulty sensor or the gauge itself.
I would also replace the pressure cap on the radiator. Also as @MickEng says It does look like a Sender / Gauge /wiring fault, whether or not the Hot wire is connected to the current issue or not it requires rectification before it causes bigger issues.
I would be wanting to investigate that electrical connector first myself as there is a danger of fire, by the sound of it, never minding that it might (could well) be something to do with the temp readings. Get good access, then disconnect the two parts of the connecter and examine carefully. I would be looking for any broken wires that are arc-ing/grounding, particularly the white one. It seems to me to be very important to get that sorted and it might fix the other temp readings problem as well. You might find that you need to push out the actual metal contact for each wire, to ensure you find exactly what is going on. On some connectors you can split them in half to access the metal contacts.
Thanks for the Input guys. I've got some more information to report back with. The wire that is getting on is the wire from the battery to the key cylinder. The smaller guage wire on the component side of the plug has gotten hot enough to burn the sheath where it's closest to the plug. Pulling the pin reveals no abnormalities
