Boiling coolant out of storage

G'day Folks, I have a sick motor and wanted to gauge some advice before pulling it apart.
The Background is-
Its a 2004 American Rocket with circa 40k miles on the clock,
Has not been ridden much the last couple of years and after 12 months sat idle i've pulled it out, stuck a new battery on it, Rebuilt the front shocks to change the oil and seals (and slung some progressive springs in there), fixed the oil reservoir leak and changed the oil and filters. I also topped up the coolant which was a smidge below min.
All good there.
The issue is-
When started the reservoir starts boil out of the relief pipe under the engine at around 95deg (according to my obd2 reader and app)
I've tested the coolant switch and it shows 2.45kOhms @22 deg so ok at cooler temps
I've tested the relays and it works, also swapped it and it still works
The fan never cuts in when the bike is running and i've had it up to 106 deg today with no fan cutting in. However if I use tuneecu to run a fan test then the fan spins up just fine. There are no error codes reported or stored and the bike runs just fine.
All of the pipes get hot as does the radiator so i guess the thermostat is working fine. That said they get hot long before it hits 88 deg on my ecu scanner.

Short of pulling out the temp sensor then i'm not sure what to do next, can't take it for its MoT test if it boils because they won't run it on the emmissions test or rolling road brake test if its whizzing boiling fluid out of the bottom.

Any anecdotes, suggestions or advice would be most appreciated.

12 years of ownership in, this is my first real Rocket issue, i don't seem to be able to find anything similar on the forums.
Mine had a similar issue a couple of gearboxes ago. Bike was without battery for around 6 months. Started up and it idled for about 5 mins then sprayed coolant around my garage. Checked all connections etc and they were all good. I rode it for a couple of weeks without any overheating issues (i generally don't have to stop on my daily commute ) and after riding it to my dad's house for a full diagnosis it just started working again.
 
Mine had a similar issue a couple of gearboxes ago. Bike was without battery for around 6 months. Started up and it idled for about 5 mins then sprayed coolant around my garage. Checked all connections etc and they were all good. I rode it for a couple of weeks without any overheating issues (i generally don't have to stop on my daily commute ) and after riding it to my dad's house for a full diagnosis it just started working again.
I love that about self healing triumphs. I would just ride it about but have lots of traffic and it needs to pass an mot first. On the subject of self healing, I once returned to port Fouchon after a 6 week hitch offshore where the bike had been sat on the quayside. Rode it just fine up to New orleans and parked it on Bourbon street near the funky pirate. Came back to it a few hours later. would not start, couldn't go anywhere. Went back to it the next day, fired up and rode back to houston. Later investigation showed that the starter switch and side stand switch had become quite oxidised in the humid air standing and all it really required was some use. Blast off the light corrosion from the switch gear.
 
Bleed the air (like said)
Then set the level at the bottom of tank (not mim or full) and give it a try
 
If u want to test fan buy a resister that will put the heat at 230-250 F
If u try to run motor w/o sensor/resistor the ecu may set a sudstitute temp of -40 and fload the motor with gas.
Many years ago i wanted to see what would happen to the customers truck i was driving if i pulled the heat sensor
It flooded so bad i almost had to call a tow truck.
 
If you have ohm tested the sensor by the book and temp values are in range " cold" and you can watch resistance change while holding it tight in your hand the sensor is operating normal if you can active the fan with output state control through tune ecu then the ecu and wiring to fan is sound I would suspect a wiring issue from your sensor to ur ecu it has no input to cycle fan 2 cents
 
So an update. New rad cap fitted and now it does not boil. I just ran it and monitored the temp up to 104 Deg and the fan did not kick in. I can activate the fan still in the tuneecu app and it works when the bike is running. When activating in tune ECU the fan relay clicks on and off with each test cycle as the fan spins up. I have bled down the system and refilled as suggested by the manual.
Soooo, the boiling issue is now sorted. But the fan not kicking in is not it seems.
Regarding the sensor to relay connection, if I unplug it then it throws an error code, so the ECU sensor circuit must be within tolerances.

The only thing I can think of next is to test the resistivity of the temp sensor when in boiling water?
 
Ok. Problem solved. Thank you all for the help and suggestions.
The story ends like this. Convinced it was a wiring issue and knowing I had taken some off to remove the intake and solve the leaking oil reservoir gasket I unplugged and went through the connections again. I had noticed that using the VAG protocol on a car scanber device the inlet air temp and coolant temp sensor readings seemed to be inverted. However, knowing they weren't throwing codes when plugged in and the sensors both tested within range and when unplugged the ECU logged a corresponding code then I continued. In attempting to swap the plugs I have found that in fact I had the air intake temp sensor plugged into the coolant place in the loom and vice versa. A rookie error if ever there was one.
Once again, thank you forum members for assisting me to solve this problem. Now I'm going to ride the beast.
 
Ok. Problem solved. Thank you all for the help and suggestions.
The story ends like this. Convinced it was a wiring issue and knowing I had taken some off to remove the intake and solve the leaking oil reservoir gasket I unplugged and went through the connections again. I had noticed that using the VAG protocol on a car scanber device the inlet air temp and coolant temp sensor readings seemed to be inverted. However, knowing they weren't throwing codes when plugged in and the sensors both tested within range and when unplugged the ECU logged a corresponding code then I continued. In attempting to swap the plugs I have found that in fact I had the air intake temp sensor plugged into the coolant place in the loom and vice versa. A rookie error if ever there was one.
Once again, thank you forum members for assisting me to solve this problem. Now I'm going to ride the beast.
Haha happens to the best of us good find! Enjoy.
 
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