we did not make anything for bleeding the system......besides, there is no i formation about bleed the system in Axious service manual, so we supposed that the bleeding will be made it self during use, just like power trim .....
It's possible that you have repaired this problem, just that you/your mechanic didn't follow the proper process.
Manual 8M0098996 OCTOBER 2016 MerCruiser Axius
You really need to read this manual. It contains a lot of information that
IS
required to correctly service this system.
This manual is almost 400 pages, but the first 84 pages are the most important. Most people want to jump right into the troubleshooting section that starts on page 85. But without the knowledge base that's in those first 84 pages they have a very good chance getting something wrong!
Most of the questions you have asked are covered in those 84 pages.
Filling and bleeding --- with the correct fluid for your application ---- is covered in...... Section 1B-Maintanance.
Section 1C- Important Information. Covers swapping components.
Section 3A - Configuration. and the reflashing checklist at the end makes sure you get it right by following the correct order.
You don't have to read and understand this information, neither does your mechanic. But I'm pretty sure the person who ends up fixing this problem will.
Please read these 84 pages (or hire someone who has) and if you have any questions after reading them, I will try to answer them. Because some of the information might be hard to understand. Before I took the Axius and Total Command class, I had to take the SmartCraft 2 and DTS class and before that I had to take ECM 1 and ECM 2 and ECM 3+. My point is that some of the information in these manuals builds on previous information. And this is what you're paying for when you hire a well trained technician.
A quick story to end this post.
Many many years ago I attended a boat manufacturer class on installing high end electronics that some of our customers had started asking for (satellite TV, night vision, auto pilot, fancy depth finders and chart plotters, ect.). The class started ---as most of these types of classes do--- with the instructor asking what problems we were seeing out in the field so he could tailor the instruction. I was seated next to a female and wow did she know her job! At break I complimented her on her knowledge. She told me how surprised she was that someone who worked on engines, drives, transmissions, heating/air conditioning and more would even attempt high end electronics.
And then she said "I'll tell you my secret" "I'm a professional and I read the instructions"
After that I started spending more time with the manuals. And it really paid off!
Good luck on this journey you have started, I'll try to help if I can.