klaborde wrote:
BubbaJon wrote:
VespaGT250 wrote:
Quote:
Hi Keith,
Main problem of piston's cooling is not that much the temperature of the oil (even if lowering it is for sure always welcome!) but more the oil circuit's pressure.
As the piston is cooled by oil jet blowing from underneath, when the pressure drops under 1,5bar (this is the minimum pressure Piaggio recommends - higher is 4,5 bar) piston's cooling becomes insufficient or inexistent in the worst cases. Oil fluidity directly impacts oil system's pressure, here is what Motul writes about its 300V 15W50 on their website:
" The SAE 15W-50 viscosity enables to compensate high engine oil dilution by unburned fuel and maintains a stable oil pressure."
In our observations, the 5W40 oil running at high outside temperatures can cause system's pressure to drop under 1,5bar, jeopardizing the piston.
As already told, this is the most logical lead we've found when analysing deeper the cracked piston, there might be others.
Cheers!
Main problem of piston's cooling is not that much the temperature of the oil (even if lowering it is for sure always welcome!) but more the oil circuit's pressure.
As the piston is cooled by oil jet blowing from underneath, when the pressure drops under 1,5bar (this is the minimum pressure Piaggio recommends - higher is 4,5 bar) piston's cooling becomes insufficient or inexistent in the worst cases. Oil fluidity directly impacts oil system's pressure, here is what Motul writes about its 300V 15W50 on their website:
" The SAE 15W-50 viscosity enables to compensate high engine oil dilution by unburned fuel and maintains a stable oil pressure."
In our observations, the 5W40 oil running at high outside temperatures can cause system's pressure to drop under 1,5bar, jeopardizing the piston.
As already told, this is the most logical lead we've found when analysing deeper the cracked piston, there might be others.
Cheers!
I dropped the bike off this past Saturday and they are doing some test that the Piaggio tech reps want done such as cold compression test, hot compression test and I believe one more.
So depending on what they find will determine if I keep this bike or not. I am really hoping it is very minor cause I do love this bike and will give the 15w50 a shot, but if they have to tear apart a brand new motor warranty or not, I'm not having it on a bike with less than 4k miles it's gone and off to something else.
Again, thank you for all this great info!!
Sean
Great idea to monitor every now and then.
Keith,
Marietta, GA
