"2nd dead bosch gen 4 motor not happy

Geeman

Member
Nov 23, 2020
45
38
Uk
Getting a little fed up with my bosch motor. 1st motor lasted just 1000miles, got replaced under warranty in covid, which took 3 months. The 2nd motor has never missed a beat until a week ago. Stopped at a mates and did 2 days of riding. Day one the sky opened up and it pissed it down big time, finished the ride, cleaned and oiled the bike and out for beer, 2nd days was cracking, 10 miles in code came up with an over load 500, ended the ride.
Got back home check the cable in the motor, one was loose, went out for a ride all good. today went out no codes 20 miles banked, put bike away, went to clean, oil check it, motor dead, nothing. Motor is out of warranty, so local shop to get it checked, but can see this as a new motor. The 2nd motor has only covered just over 1000miles. utterly fed up, these motors should last for 1000s of miles.
 

Geeman

Member
Nov 23, 2020
45
38
Uk
So a little update from the 1st motor. I never found out what went wrong with it, Just that its fired!!!!. I didn't ask anymore, just wanted my bike back to get out and ride. Rang bike shop this morning, run through a few things, none of them have worked. So needs a diagnostics check, Which will show its knackered no doubt. Got told Bosch will exchange it for around £650 brand new 2 years warranty, which is suppose to be a good deal, Usually £750. Not sure what to do?? Local shop who I thought repaired and rebuilt the motors, wont do them anymore, said its a ball ache. Seen a few motors on ebay from germany which might be an option. But in all honesty, I love my ebike, but this could be a change back to analogue. These motors are not fit for purpose. The lucky ones who get 5k plus out a motor, well im very jealous. I can afford a new motor, but its the principle of the matter, why the hell should I. A warranty on these motors should be mileage not the age of the dam things. What should be a good mileage out of a motor, 5k 10k 15k??? certainly not just over a 1000miles.
 
Last edited:

Zimmerframe

MUPPET
Subscriber
Jun 12, 2019
13,907
20,614
Brittany, France
Life span seems to vary a lot between riders and use.

You see the cargo bikes and even people who use their EMTB's mainly for touring get 20,000 30,000 and more KM's (even Shimano's) The motors don't get the same physical strain/knocks/strikes and presumably don't get the same level of water contact.

A lot of people jet wash their bikes and take the view that the bike will/should take it. But the better the bearings are sealed, the more drag there will be - people don't want drag, so they're not heavily protected. The gen4 is packed with grease behind a cover. If you're regularly riding in extremely wet conditions, washing the bike with "enthusiasm" or carrying the bike on the back of a car - the grease needs changing fairly regularly to protect the motor longer term.

The main Gen4 problem is that the circuit board is at the bottom, so if any water does get in, it fecks that. Whilst it's possible to fix the motor mechanically, repair companies are then often on the hook because they then find the board is also fried and have to provide a new motor.

My Brose is on it's last legs, but only because I was a knob and submerged it regularly and excessively (though it's always had an issue from new so I didn't care about it anymore).

Price wise, I think £650 sounds pretty good for a new motor when you consider what most of them seem to be priced at.
 

Paulquattro

E*POWAH Elite
May 7, 2020
2,046
1,119
The Darkside
Getting a little fed up with my bosch motor. 1st motor lasted just 1000miles, got replaced under warranty in covid, which took 3 months. The 2nd motor has never missed a beat until a week ago. Stopped at a mates and did 2 days of riding. Day one the sky opened up and it pissed it down big time, finished the ride, cleaned and oiled the bike and out for beer, 2nd days was cracking, 10 miles in code came up with an over load 500, ended the ride.
Got back home check the cable in the motor, one was loose, went out for a ride all good. today went out no codes 20 miles banked, put bike away, went to clean, oil check it, motor dead, nothing. Motor is out of warranty, so local shop to get it checked, but can see this as a new motor. The 2nd motor has only covered just over 1000miles. utterly fed up, these motors should last for 1000s of miles.
I totally agree
The bikes are effectively unfit for purpose and £650 every thousand miles is not a good deal
I would rather have a better sealed motor with extra seal drag than a motor your afraid of getting wet
Its a shambles in all honesty :(
I hope you get something sorted (y)
 

Geeman

Member
Nov 23, 2020
45
38
Uk
:mad::mad::mad::mad::mad::mad:
I totally agree
The bikes are effectively unfit for purpose and £650 every thousand miles is not a good deal
I would rather have a better sealed motor with extra seal drag than a motor your afraid of getting wet
Its a shambles in all honesty :(
I hope you get something sorted (y)
I'm just now sat with my laptop looking at eBike Motor Centre. £360 for a full rebuild. If it can be repaired. They say 90% success rate.
 

EuanS2

Well-known member
Subscriber
Jan 10, 2021
90
126
Edinburgh
My first Gen 4 went at roughly 1000 miles, one of my mates is also on his second Gen 4, surprise surprise, his also went at roughly 1000 miles. I asked the bike shop about this and they also said they had seen a number of bikes with motors gone at roughly 1000 miles... I'd hate to think what sort of mileage to so called more unreliable manufacturers are getting if the Bosch motors are only getting 1000 miles of usage
 

samohtr

Member
Jul 24, 2020
42
22
St Albans
Mine went at just 2175 miles / 2.5 years. No mechanical signs just sensor error messages, 513, 500 & 550 before it finally stopped communicating with my kiox and died. I think mine was a water issue from a few really deep puddle dunkings and probably jet washing once a week. Luckily for me my LBS (bosch dealer) got me a warranty replacement. Being a bit more careful on the washing front now.

I too went through the dilemma of what to do, before I got the warranty replacement. Mechanically they are not to bad to fix or refurb. However electrotonically it is a no go.
 

Geeman

Member
Nov 23, 2020
45
38
Uk
Mine went at just 2175 miles / 2.5 years. No mechanical signs just sensor error messages, 513, 500 & 550 before it finally stopped communicating with my kiox and died. I think mine was a water issue from a few really deep puddle dunkings and probably jet washing once a week. Luckily for me my LBS (bosch dealer) got me a warranty replacement. Being a bit more careful on the washing front now.

I too went through the dilemma of what to do, before I got the warranty replacement. Mechanically they are not to bad to fix or refurb. However electrotonically it is a no go.
Thank you for the reply.
My local Bosch centre wants my old motor and £650 for a brand new 2 years warranty motor, I declined on principle. I won't ever buy a new eBike again, The prices are just beyond stupid now. Just hoping eBike motor centre get it sorted. The circuit boards in gen 4 motors cannot be that expensive, don't look it. Should be just plug in and go. Right to repair or a better warranty on milage not date of purchase. 1000miles is nothing.
 

irie

E*POWAH Elite World Champion
Subscriber
May 2, 2022
2,233
2,165
Chichester, W.Sussex, UK
Getting a little fed up with my bosch motor. 1st motor lasted just 1000miles, got replaced under warranty in covid, which took 3 months. The 2nd motor has never missed a beat until a week ago. Stopped at a mates and did 2 days of riding. Day one the sky opened up and it pissed it down big time, finished the ride, cleaned and oiled the bike and out for beer, 2nd days was cracking, 10 miles in code came up with an over load 500, ended the ride.
Got back home check the cable in the motor, one was loose, went out for a ride all good. today went out no codes 20 miles banked, put bike away, went to clean, oil check it, motor dead, nothing. Motor is out of warranty, so local shop to get it checked, but can see this as a new motor. The 2nd motor has only covered just over 1000miles. utterly fed up, these motors should last for 1000s of miles.
Exactly how did you clean your bike?
 

Geeman

Member
Nov 23, 2020
45
38
Uk
Exactly how did you clean your bike?
Spray with basic hose pipe, to get most of the loose stuff off, then use brushes or sponge. But to add to this, in the UK West Yorkshire the weather is shit most of the time heavy rain, snow, bit of sun now and again.
 

samohtr

Member
Jul 24, 2020
42
22
St Albans
Thank you for the reply.
My local Bosch centre wants my old motor and £650 for a brand new 2 years warranty motor, I declined on principle. I won't ever buy a new eBike again, The prices are just beyond stupid now. Just hoping eBike motor centre get it sorted. The circuit boards in gen 4 motors cannot be that expensive, don't look it. Should be just plug in and go. Right to repair or a better warranty on milage not date of purchase. 1000miles is nothing.
I spoke to one of the refurb places and the very helpful chap there said that the sensors are calibrated to each motor in the factory. They had little success in swapping the torque sensor and pcb's on the Gen 4, earlier ones were no problem. Just checking my emails it was Peter at the ebike motor centre. They were very helpful and it was where I was going to send mine unitl I got the warranty one.
 

jackamo

Active member
Subscriber
May 25, 2023
86
52
UK
Getting a little fed up with my bosch motor. 1st motor lasted just 1000miles, got replaced under warranty in covid, which took 3 months. The 2nd motor has never missed a beat until a week ago. Stopped at a mates and did 2 days of riding. Day one the sky opened up and it pissed it down big time, finished the ride, cleaned and oiled the bike and out for beer, 2nd days was cracking, 10 miles in code came up with an over load 500, ended the ride.
Got back home check the cable in the motor, one was loose, went out for a ride all good. today went out no codes 20 miles banked, put bike away, went to clean, oil check it, motor dead, nothing. Motor is out of warranty, so local shop to get it checked, but can see this as a new motor. The 2nd motor has only covered just over 1000miles. utterly fed up, these motors should last for 1000s of miles.
Bosch have been going over the 2 year warranty period for a while now .
Give them a try as they can only say no.
 

Bearing Man

Ebike Motor Centre
Patreon
Sep 29, 2018
919
2,205
UK
:mad::mad::mad::mad::mad::mad:

I'm just now sat with my laptop looking at eBike Motor Centre. £360 for a full rebuild. If it can be repaired. They say 90% success rate.
Peter here from the eBike Motor Centre, please note as stated on our site, our high success rate is with the Bosch Gen 2, a very different animal to the Gen 4.
Mechanically they are not to bad to fix or refurb. However electrotonically it is a no go.
Mechanically, these motors are quite difficult to get apart without braking something, and even more difficult to put back together without any issues or fault codes. When you watch people like the Yorkshire mechanic, this is not real life!
I spoke to one of the refurb places and the very helpful chap there said that the sensors are calibrated to each motor in the factory. They had little success in swapping the torque sensor and pcb's on the Gen 4, earlier ones were no problem. Just checking my emails it was Peter at the ebike motor centre.
Just to clarify this. The printed circuit board (PCB) is calibrated to the three phase electric motors firing angle. This means taking a board from another motor does not usually work unless you're extremely lucky.
The torque sensor is very delicate and susceptible to water, magnetism and shock. Unfortunately it's also calibrated to the freewheel sleeve and crankshaft. If there is any issue with this part, the entire crankshaft assembly and sensor must be transplanted from a donor motor.
 

Geeman

Member
Nov 23, 2020
45
38
Uk
Peter here from the eBike Motor Centre, please note as stated on our site, our high success rate is with the Bosch Gen 2, a very different animal to the Gen 4.

Mechanically, these motors are quite difficult to get apart without braking something, and even more difficult to put back together without any issues or fault codes. When you watch people like the Yorkshire mechanic, this is not real life!

Just to clarify this. The printed circuit board (PCB) is calibrated to the three phase electric motors firing angle. This means taking a board from another motor does not usually work unless you're extremely lucky.
The torque sensor is very delicate and susceptible to water, magnetism and shock. Unfortunately it's also calibrated to the freewheel sleeve and crankshaft. If there is any issue with this part, the entire crankshaft assembly and sensor must be transplanted from a donor motor.
Cheers for the reply. This has totally put me off buying another expensive emtb, as much as I do love them.
 

Geeman

Member
Nov 23, 2020
45
38
Uk
👋👋👋👋 Hello.
Got my motor back, it's fitted and working in my bike stand. Just waiting for some new parts, then it's listed to sell. Totally fallen out with the eBike vibe. Ordered a new analogue bike. So happy trails.
PLUS A BIG THANK YOU eBike motor centre (Peter) epic👍👍
 

mmcengineer

Member
Jan 3, 2022
56
61
Sheffield
Peter here from the eBike Motor Centre, please note as stated on our site, our high success rate is with the Bosch Gen 2, a very different animal to the Gen 4.

Mechanically, these motors are quite difficult to get apart without braking something, and even more difficult to put back together without any issues or fault codes. When you watch people like the Yorkshire mechanic, this is not real life!

Just to clarify this. The printed circuit board (PCB) is calibrated to the three phase electric motors firing angle. This means taking a board from another motor does not usually work unless you're extremely lucky.
The torque sensor is very delicate and susceptible to water, magnetism and shock. Unfortunately it's also calibrated to the freewheel sleeve and crankshaft. If there is any issue with this part, the entire crankshaft assembly and sensor must be transplanted from a donor motor.
I sat and read this having worked in some pretty serious engineering companies and wondered who the fuck lets designers make manufacturing and assembly decisions like this to write an entire component assembly off rather than allow it to be repairable in a simple manner, it sounds more like the entire policy is labour costs so much these days just to swap the entire unit as a rule, it can’t seriously be environmentally friendly to keep scrapping high value shit like we are with these motors , but I guess that’s why they want the motors back when you get a new one
 

A22

New Member
Oct 20, 2023
25
14
New Zealand
I sat and read this having worked in some pretty serious engineering companies and wondered who the fuck lets designers make manufacturing and assembly decisions like this to write an entire component assembly off rather than allow it to be repairable in a simple manner, it sounds more like the entire policy is labour costs so much these days just to swap the entire unit as a rule, it can’t seriously be environmentally friendly to keep scrapping high value shit like we are with these motors , but I guess that’s why they want the motors back when you get a new one
Completely agree, the eMTB manufactures culture of replace instead of fix is not environmental sustainable. I’d pay more for a serviceable motor.
 

Bearing Man

Ebike Motor Centre
Patreon
Sep 29, 2018
919
2,205
UK
in bikes where the motor is rotated is it still the bottom?
Some motors yes, some no. To be honest, most new motors of any make, the PCB is wrapped around the motor to fit it all in and this means it goes from top to bottom. This is just another consequence of everyone wanting smaller motors.
 

RustyMTB

E*POWAH Elite World Champion
Jul 22, 2020
2,694
6,531
UK
Coming up on 3500 miles on my hard driven motor with (this will shaft it) no problems. It's well known I am pretty conscientious about keeping water out of the outer seals but that hydrophobic nerding extends to how I try to ride & clean the bike but on another site, I've been reading about a guy whose just blown up his fifth Gen4 in three years burning around semi submerged Yorkshire.

Either that guy is very unlucky or is a puddle/Karcher enthusiast. My view is any motor can fail but with these specific units, there is really only one weak point letting water in & it's not really even a weak point, more a pragmatic design choice that the user should be taking into account during their ownership.

Unsurprisingly, you won't find anything from Bosch telling you to how to preserve your motor, that would involve an uncomfortable admission, so it's left to the user community to work things out.
 

irie

E*POWAH Elite World Champion
Subscriber
May 2, 2022
2,233
2,165
Chichester, W.Sussex, UK
... with these specific units, there is really only one weak point letting water in & it's not really even a weak point, more a pragmatic design choice that the user should be taking into account during their ownership.

Agree.

There obviously has to be a hole for the cranks to turn, so do NOT spray water in that area, pressurised or otherwise! Simply brush muck off with a dry brush.

Rocket science. Not.
 

Cobee

Member
Apr 30, 2023
23
36
Poland
I will plan replace bearings (left and right crank) in gen4 bosch motor. In my motor i hear some clatch. Is possible to make - i heare that need to be very carefull with sensor, position of axe iss matter ? I have tools for assemby and dissasembly bearings.
Bearing Man - havey you some guides for gen4 ? gold tips.
Thanks.
 

Bearing Man

Ebike Motor Centre
Patreon
Sep 29, 2018
919
2,205
UK
I will plan replace bearings (left and right crank) in gen4 bosch motor. In my motor i hear some clatch. Is possible to make - i heare that need to be very carefull with sensor, position of axe iss matter ? I have tools for assemby and dissasembly bearings.
Bearing Man - havey you some guides for gen4 ? gold tips.
Thanks.
My best tip would be to leave it alone! The Bosch Gen 4 is a very difficult motor to repair. Be very carful of the crankshaft, if you pull it or lift it before removing the torque sensor screw or armature and transfer gears, you will break the torque sensor. You will also struggle to remove and refit the main drive gear (a tool for refitting this gear is available from us or our partners if you are outside of the UK). DO NOT shock or drop the freewheel sleeve or crank assembly and definitely don't get a magnet near it. I could spend an hour telling you all the things to look out for, but if you decide to have a go, just be very carful and very delicate with it... Best of luck too.
 

Stihldog

Handheld Power Tool
Subscriber
Jun 10, 2020
3,179
4,407
Coquitlam, BC
My best tip would be to leave it alone! The Bosch Gen 4 is a very difficult motor to repair.
I’d personally heed these warnings. The YouTube rebuild help videos are heavily edited or the critical steps are confusing and incomplete. They tend to show the complexity and special tools required.

Back in the day, on your vehicle, you could return the “core” of an alternator, water pump, carburetor, etc, for a small price reduction. I always assumed that the “core” would be rebuilt and re-sold.

My knowledge and speciality tools are limited to a Bearing Seal replacement kit. Fairly easy to do, cheap, and part of regular maintenance. The YouTube videos are fairly easy to follow also. A few specific tools are required (torque wrench, spider socket, crank puller).

I’ve either been lucky or fortunate with my Bosch CX motor. 4 years old, ridden almost daily, all types of weather, and completely submerged (submarined) several times. I know that someday this motor will fail.…and when it does I can sell off my wife’s shoe collection to pay for repairs. 😉
 

irie

E*POWAH Elite World Champion
Subscriber
May 2, 2022
2,233
2,165
Chichester, W.Sussex, UK
I know that someday this motor will fail.…and when it does I can sell off my wife’s shoe collection to pay for repairs. 😉
I'll see your wife's 👞 collection and raise you with my wife's 👜 collection!
handbag.gif
 

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