CX Gen 2 slipping under load

[Sessions]

Hi,

my CX Gen 2 recently started slipping under load on technical sections at low speed, now also when going uphill over small roots or rocks. I can hear cogwheels slipping, motor rpm increases for a second with no power transferred and then it reangages.

Bearings are also failing, as it is producing a grinding sound and there is play in the cranks, especially on the non-drive side (I replace the protective felt rings and add grease on the drive side quarterly)

It’s a 2.5 year old motor replaced on warranty with 10.5 K km on the clock. It is now out of warranty.

What can be the cause of the motor slipping and can this be fixed while also changing bearings or do I need a new motor?

 

[Sessions]

Update

• I sent the motor to a bike shop repairing Bosch motors
• I was informed that the motor got in moisture from the non-drive side, which is not possible to protect with felt rings. This caused dirt getting in and bearing failure in the long run
• Bike shop replaced all the bearings, informed me that cogwheels are fine and it should all be good, they said it was slipping because of loose bearings
• Today, I got the motor back after two weeks and it’s still slipping in Tour, EMTB and Turbo, even more than before. Now it is enough that I put some limited pressure on the pedals and it slips. The bike is now completely unusable

I am devastated, as I just had to cancel a planned trip to the mountains this weekend and I fear this will take months to resolve. EMTB is my only hobby and helps me to cope with all the challenges in my life, I really don’t want to be off my only bike for months.

Attaching a pic from before and after the bearing change and cleaning.

Questions

• What is the possible cause for motor slipping? Some kind of faulty clutch?
• Is this repairable and if yes, what part needs replacement? Or do I ned a new motor from Bosch?

Thankful for your advice, guys!

 

[Bones]

Send it back to the repair shop and let them sort it out. There's not much else you can do really.

 

[Sessions]

Thanks, did that. Also asked another repair shop for advice and they think it is definitely the small clutch bearing, possibly caused by a cracked gear. Hope my shop will just replace all these parts with the Bosch Gen 2 motor service repair kit BDU2xx but they said they will likely look for the problem first and decide what to do. Will post the outcome here when the motor is fixed.

 

[Sessions]

Hi guys,

promised to post the outcome. It was the clutch bearing. The repair shop replaced the parts with the service kit. AOK after four rides.