coolant woes

[Cagey_Thoughts]

Hi all... confirmation of thoughts please...
Just had the Fazer out for a test ride after a full frame swap... ride went great but she dumped a load of coolant on the garage floor out of the expansion tank vent pipe when I got back!!!
now... 64 million dollar question... is it worth going... cap... thermostat... before I go head gasket??? There is quite a build up of pressure when opening the cap... even now when it is cold... I will try and post a diagram of how I have installed the pipework... most have been changed for new from AS3... 

  Fazer Coolant Routes.jpg (Size: 49.94 KB / Downloads: 19)

[Gnasher]

If all you've done is swap the frame and the motor was running fine with no coolant issues, was it?  You've refitted everything as it should be eg pipework etc, it's likely you've got nothing more than an air lock. There should be pressure in the system even when cold for a day or so after riding, it's a sealed system.

[Cagey_Thoughts]

thanks Gnasher... I did have a split hose on a ride just before the frame swap and the engine got really hot...  that's how i realised that I needed to change the hoses after 23 years...lol... and hence my fears for the head gasket... although I'm guessing that there would be a loss of pressure in the system if it had gone???  There is no oil in the coolant and no coolant in the oil... The cap and thermostat are also 23 years old.. so I'm changing them... (I've had the bike from new... so I know its history)... That's when I swapped the frame to the French registered one... filled the coolant... had no leaks on the bench when running the engine up... but on its first ride out... and I stopped a couple of times with no signs of anything wrong... all was going well until I got home and the coolant deposited itself on the garage floor through the expansion tank vent pipe... The engine was still running at this point... there shouldn't be any blockages I recently fitted a new radiator and when I took the cap off on the bench with the engine running there was plenty of flow coming from the carbs and from the block...  I am waiting for the cap and thermostat to arrive from the UK...  I'll put them on the bike... have a look at seeing if there are any air locks... and try again...lol

[darrsi]

thanks Gnasher... I did have a split hose on a ride just before the frame swap and the engine got really hot...  that's how i realised that I needed to change the hoses after 23 years...lol... and hence my fears for the head gasket... although I'm guessing that there would be a loss of pressure in the system if it had gone???  There is no oil in the coolant and no coolant in the oil... The cap and thermostat are also 23 years old.. so I'm changing them... (I've had the bike from new... so I know its history)... That's when I swapped the frame to the French registered one... filled the coolant... had no leaks on the bench when running the engine up... but on its first ride out... and I stopped a couple of times with no signs of anything wrong... all was going well until I got home and the coolant deposited itself on the garage floor through the expansion tank vent pipe... The engine was still running at this point... there shouldn't be any blockages I recently fitted a new radiator and when I took the cap off on the bench with the engine running there was plenty of flow coming from the carbs and from the block...  I am waiting for the cap and thermostat to arrive from the UK...  I'll put them on the bike... have a look at seeing if there are any air locks... and try again...lol

You may have fitted a new radiator, but did you clean the whole coolant system at the same time? 
As well as air bubbles in the system, which can be sorted easily enough by raising the tank in whichever way you feel safest, and letting the engine tick over with the radiator cap off, and the bubbles will rise to the top then escape out of the radiator. 
But if you haven't done so I would still use Radflush to clean the system out if you didn't already do it, because blocked waterways will also cause the coolant to boil, overload the expansion tank, then dump any excess out of the overflow pipe, as you're describing.
As mentioned above, it's a sealed system when working properly and you can even see if everything is okay  when the bike has cooled down, as the fluid will generally settle at the same level in the expansion tank which you can see in the tank by rocking the bike a bit on the centre stand. You might get a minor loss in very hot conditions, but a very minimal amount that can always be topped up if noticed.

[Cagey_Thoughts]

Cheers darrsi... I'll get some radflush and push that through the system... Thanks for all your help people... Trying to keep the old girl going in tip top condition... photo was taken in the UK in 2021, before we moved to France.