Malaguti Spidermax - how to bleed air out of the coolant system

Inside the cooling system of the Piaggio MASTER engine


The nice thing if you have a problem and you have 2 of the same you can compare behavior.
I started both  Spidermax and took pictures how many bars the temp gauge was showing after a certain time.
While the GT ( the old one) was going to 4 bars and stayed there after 2 minutes, the RS was climbing and climbing.
After 3 min the RS was switching on the coolant fan while the GT opened the second stage radiator to keep the temp around 4 bars. This shows when after climbing to 5 bars the temp drops down to 4 bars without engaging the fan.
After 4 minutes the RS was up to 10 bars and the red warning light for engine overheating turned on.
The fan did blow only cold air.

 The RS stayed at 4 bars after 5 minutes idle.

Here you can see how warm your engine is. (parziale = temperature bar)

So now we have to check if water is in and air is out of all pipes.
To get to the two radiators some disassembly is required.
Take off the mirrors, take off the front faring (nose), take off the windscreen, take of the foot rests, take off the side panels with the lights.
15 min later you can reach everything - well nearly.
Also take off the left black triangle (no screws) to get to the motor.

Drain some coolant from the overflow bottle via a thin hose, so you have some coolant to top off the radiator.
Remove the radiator cap



Short interruption for a Spidermax cooling system lession

Engine (8) starts and water pump (9) circulates water in the small circle.

The valve (7) opens at 80-84 degrees and the water circulates now through radiator (1) and the engine. At 63-67 degrees the valve (5) opens the way to the second radiator (3).
The cooling fan on the main radiator (1) kicks in if that is still not enough and the water temperature is over 100 degrees.

end interruption

To get the air our from the bottom we need to start with the engine. There is a bleeder valve what you can open with a 8mm nut.

 Let the engine run and slowly open a bit until just water seeps out, close when just coolant runs out.

Next step is to check the already open radiator, top up coolant and look out for bubbles emerging.  
You might need to do that a few times.

Close the radiator cap if the water level rises and no more bubbles are emerging.

The last step is to open the bleeding screw on the second radiator when you notice that the radiator gets warm.

Let dribble until no more air is in the radiator.

I drained 600 ml out of the overflow bottle

after filling up the coolant level in the radiator.

I needed 150 ml to replace air with coolant and at least 30 ml got lost during bleeding.
After all this work my RS now behaves the way she should.
10 min idle and not over 4 bars. The second stage radiator kicks in and then the cooling fan. This time it blows hot air.
So I am quite happy with this outcome and already have the side panels off for an easier paint job.
Testing it a second time in the evening provided the same results.

Since we have everything now in easy access, I revisited my coolant level checker and modified the length a bit.

60 cm plastic hose and 20 cm inside the overflow bottle

with 20 cm length the pipe is in the medium water level

water level checker installed

water level checker sucks coolant after a short press on the ball pump - so everything is hunky dory (OK)